| author | amit@thunder |
| Tue, 23 Feb 2010 19:43:04 +0530 | |
| changeset 25 | ed38dd9bdb50 |
| parent 24 | 10074d1357ff |
| child 27 | cb14131583c6 |
| permissions | -rw-r--r-- |
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The first commit of all the required files for the review app
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<html> |
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<head> |
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> |
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<title> |
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Chapter. func |
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</title> |
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<link rel="stylesheet" href="/review/support/styles.css" type="text/css" /> |
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<meta name="generator" content="DocBook XSL Stylesheets V1.74.3" /> |
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<link rel="shortcut icon" type="image/png" href="/review/support/figs/favicon.png" /> |
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<script type="text/javascript" src="/review/support/jquery-min.js"> |
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</script> |
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<script type="text/javascript" src="/review/support/form.js"> |
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</script> |
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<script type="text/javascript" src="/review/support/hsbook.js"> |
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</script> |
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</head> |
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> |
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<div class="chapter" id="ch5func"> |
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<div class="titlepage"> |
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</div> |
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<div class="toc"> |
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<p> |
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<b> |
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Table of Contents |
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</b> |
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</p> |
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<dl> |
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<dt> |
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<span class="article"> |
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<a href="#id2621478"> |
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Functional Approach |
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</a> |
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</span> |
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</dt> |
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<dd> |
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<dl> |
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<dt> |
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<span class="section"> |
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<a href="#id2672516"> |
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1. Function scope |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672574"> |
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2. Default Arguments |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672613"> |
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3. Keyword Arguments |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672729"> |
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4. Parameter Packing and Unpacking |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672829"> |
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5. Nested Functions and Scopes |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672879"> |
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6. map, reduce and filter functions |
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</a> |
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</span> |
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</dt> |
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<dd> |
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<dl> |
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<dt> |
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<span class="section"> |
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<a href="#id2673069"> |
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6.1. List Comprehensions |
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</a> |
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</span> |
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</dt> |
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</dl> |
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</dd> |
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</dl> |
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</dd> |
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</dl> |
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</div> |
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<div class="article" title="Functional Approach"> |
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<div class="titlepage"> |
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<div> |
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<div> |
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<h2 class="title"> |
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<a name="id2621478"> |
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</a> |
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Functional Approach |
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</h2> |
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</div> |
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</div> |
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<hr /> |
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</div> |
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<div class="toc"> |
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<p> |
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<b> |
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Table of Contents |
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</b> |
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</p> |
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<dl> |
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<dt> |
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<span class="section"> |
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<a href="#id2672516"> |
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1. Function scope |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672574"> |
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2. Default Arguments |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672613"> |
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3. Keyword Arguments |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672729"> |
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4. Parameter Packing and Unpacking |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672829"> |
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5. Nested Functions and Scopes |
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</a> |
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</span> |
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</dt> |
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<dt> |
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<span class="section"> |
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<a href="#id2672879"> |
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6. map, reduce and filter functions |
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</a> |
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</span> |
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</dt> |
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<dd> |
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<dl> |
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<dt> |
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<span class="section"> |
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<a href="#id2673069"> |
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6.1. List Comprehensions |
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</a> |
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</span> |
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</dt> |
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</dl> |
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</dd> |
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</dl> |
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</div> |
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<p id="ch5func_1"> |
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<span class="emphasis"> |
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<em> |
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Functions |
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</em> |
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</span> |
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allow us to enclose a set of statements and call the function again |
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and again instead of repeating the group of statements everytime. Functions also |
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allow us to isolate a piece of code from all the other code and provides the |
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convenience of not polluting the global variables. |
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</p> |
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<p id="ch5func_2"> |
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<span class="emphasis"> |
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<em> |
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Function |
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</em> |
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</span> |
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in python is defined with the keyword |
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<span class="strong"> |
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<strong> |
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def |
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</strong> |
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</span> |
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followed by the name |
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of the function, in turn followed by a pair of parenthesis which encloses the |
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list of parameters to the function. The definition line ends with a ':'. The |
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definition line is followed by the body of the function intended by one block. |
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The |
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<span class="emphasis"> |
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<em> |
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Function |
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</em> |
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</span> |
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must return a value: |
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</p> |
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<pre class="programlisting"> |
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def factorial(n): |
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fact = 1 |
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for i in range(2, n): |
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fact *= i |
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return fact |
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</pre> |
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<p id="ch5func_3"> |
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The code snippet above defines a function with the name factorial, takes the |
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number for which the factorial must be computed, computes the factorial and |
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returns the value. |
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</p> |
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<p id="ch5func_4"> |
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A |
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<span class="emphasis"> |
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<em> |
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Function |
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</em> |
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</span> |
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once defined can be used or called anywhere else in the program. We |
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call a fucntion with its name followed by a pair of parenthesis which encloses |
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the arguments to the function. |
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</p> |
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<p id="ch5func_5"> |
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The value that function returns can be assigned to a variable. Let's call the |
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above function and store the factorial in a variable: |
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</p> |
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<pre class="programlisting"> |
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fact5 = factorial(5) |
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</pre> |
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<p id="ch5func_6"> |
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The value of fact5 will now be 120, which is the factorial of 5. Note that we |
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passed 5 as the argument to the function. |
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</p> |
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<p id="ch5func_7"> |
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It may be necessary to document what the function does, for each of the function |
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to help the person who reads our code to understand it better. In order to do |
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this Python allows the first line of the function body to be a string. This |
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string is called as |
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<span class="emphasis"> |
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<em> |
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Documentation String |
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</em> |
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</span> |
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or |
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<span class="emphasis"> |
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<em> |
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docstring |
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</em> |
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</span> |
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. |
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<span class="emphasis"> |
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<em> |
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docstrings |
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</em> |
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</span> |
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prove |
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to be very handy since there are number of tools which can pull out all the |
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docstrings from Python functions and generate the documentation automatically |
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from it. |
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<span class="emphasis"> |
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<em> |
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docstrings |
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</em> |
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</span> |
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for functions can be written as follows: |
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</p> |
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<pre class="programlisting"> |
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def factorial(n): |
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'Returns the factorial for the number n.' |
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fact = 1 |
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for i in range(2, n): |
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fact *= i |
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|
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return fact |
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</pre> |
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<p id="ch5func_8"> |
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An important point to note at this point is that, a function can return any |
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Python value or a Python object, which also includes a |
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<span class="emphasis"> |
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<em> |
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Tuple |
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</em> |
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</span> |
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. A |
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<span class="emphasis"> |
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<em> |
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Tuple |
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</em> |
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</span> |
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is |
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just a collection of values and those values themselves can be of any other |
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valid Python datatypes, including |
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<span class="emphasis"> |
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<em> |
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Lists |
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</em> |
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</span> |
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, |
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<span class="emphasis"> |
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<em> |
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Tuples |
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</em> |
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</span> |
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, |
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<span class="emphasis"> |
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<em> |
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Dictionaries |
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</em> |
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</span> |
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among other |
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things. So effectively, if a function can return a tuple, it can return any |
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number of values through a tuple |
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</p> |
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<p id="ch5func_9"> |
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Let us write a small function to swap two values: |
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</p> |
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<pre class="programlisting"> |
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def swap(a, b): |
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return b, a |
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325 |
|
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c, d = swap(a, b) |
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</pre> |
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<div class="section" title="1.Function scope"> |
| 6 | 329 |
<div class="titlepage"> |
330 |
<div> |
|
331 |
<div> |
|
332 |
<h2 class="title" style="clear: both"> |
|
| 25 | 333 |
<a name="id2672516"> |
| 6 | 334 |
</a> |
|
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1.Function scope |
| 6 | 336 |
</h2> |
337 |
</div> |
|
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</div> |
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</div> |
|
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<p id="ch5func_a"> |
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The variables used inside the function are confined to the function's scope |
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and doesn't pollute the variables of the same name outside the scope of the |
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function. Also the arguments passed to the function are passed by-value if |
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it is of basic Python data type: |
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</p> |
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<pre class="programlisting"> |
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def cant_change(n): |
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n = 10 |
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|
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n = 5 |
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cant_change(n) |
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</pre> |
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<p id="ch5func_b"> |
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354 |
Upon running this code, what do you think would have happened to value of n |
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355 |
which was assigned 5 before the function call? If you have already tried out |
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356 |
that snippet on the interpreter you already know that the value of n is not |
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357 |
changed. This is true of any immutable types of Python like |
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|
358 |
<span class="emphasis"> |
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|
359 |
<em> |
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|
360 |
Numbers |
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|
361 |
</em> |
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|
362 |
</span> |
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|
363 |
, |
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|
364 |
<span class="emphasis"> |
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|
365 |
<em> |
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|
366 |
Strings |
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|
367 |
</em> |
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|
368 |
</span> |
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|
369 |
and |
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|
370 |
<span class="emphasis"> |
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|
371 |
<em> |
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|
372 |
Tuples |
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|
373 |
</em> |
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|
374 |
</span> |
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375 |
. But when you pass mutable objects like |
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376 |
<span class="emphasis"> |
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377 |
<em> |
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378 |
Lists |
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|
379 |
</em> |
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|
380 |
</span> |
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|
381 |
and |
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|
382 |
<span class="emphasis"> |
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|
383 |
<em> |
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|
384 |
Dictionaries |
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385 |
</em> |
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|
386 |
</span> |
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387 |
the values are manipulated even outside the function: |
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388 |
</p> |
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389 |
<pre class="programlisting"> |
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390 |
>>> def can_change(n): |
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391 |
... n[1] = James |
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|
392 |
... |
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|
393 |
|
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394 |
>>> name = ['Mr.', 'Steve', 'Gosling'] |
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395 |
>>> can_change(name) |
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|
396 |
>>> name |
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|
397 |
['Mr.', 'James', 'Gosling'] |
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|
398 |
</pre> |
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|
399 |
<p id="ch5func_c"> |
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|
400 |
If nothing is returned by the function explicitly, Python takes care to return |
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|
401 |
None when the funnction is called. |
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|
402 |
</p> |
| 6 | 403 |
</div> |
|
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|
404 |
<div class="section" title="2.Default Arguments"> |
| 6 | 405 |
<div class="titlepage"> |
406 |
<div> |
|
407 |
<div> |
|
408 |
<h2 class="title" style="clear: both"> |
|
| 25 | 409 |
<a name="id2672574"> |
| 6 | 410 |
</a> |
|
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|
411 |
2.Default Arguments |
| 6 | 412 |
</h2> |
413 |
</div> |
|
414 |
</div> |
|
415 |
</div> |
|
|
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|
416 |
<p id="ch5func_d"> |
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|
417 |
There may be situations where we need to allow the functions to take the |
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|
418 |
arguments optionally. Python allows us to define function this way by providing |
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|
419 |
a facility called |
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|
420 |
<span class="emphasis"> |
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|
421 |
<em> |
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|
422 |
Default Arguments |
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|
423 |
</em> |
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|
424 |
</span> |
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|
425 |
. For example, we need to write a function |
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|
426 |
that returns a list of fibonacci numbers. Since our function cannot generate an |
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|
427 |
infinite list of fibonacci numbers, we need to specify the number of elements |
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|
428 |
that the fibonacci sequence must contain. Suppose, additionally, we want to the |
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|
429 |
function to return 10 numbers in the sequence if no option is specified we can |
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|
430 |
define the function as follows: |
| 6 | 431 |
</p> |
432 |
<pre class="programlisting"> |
|
|
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|
433 |
def fib(n=10): |
|
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|
434 |
fib_list = [0, 1] |
|
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|
435 |
for i in range(n - 2): |
|
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|
436 |
next = fib_list[-2] + fib_list[-1] |
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|
437 |
fib_list.append(next) |
|
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|
438 |
return fib_list |
| 6 | 439 |
</pre> |
|
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|
440 |
<p id="ch5func_e"> |
|
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|
441 |
When we call this function, we can optionally specify the value for the |
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|
442 |
parameter n, during the call as an argument. Calling with no argument and |
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|
443 |
argument with n=5 returns the following fibonacci sequences: |
| 6 | 444 |
</p> |
445 |
<pre class="programlisting"> |
|
|
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|
446 |
fib() |
|
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|
447 |
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34] |
|
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|
448 |
fib(5) |
|
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|
449 |
[0, 1, 1, 2, 3] |
| 6 | 450 |
</pre> |
451 |
</div> |
|
|
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|
452 |
<div class="section" title="3.Keyword Arguments"> |
| 6 | 453 |
<div class="titlepage"> |
454 |
<div> |
|
455 |
<div> |
|
456 |
<h2 class="title" style="clear: both"> |
|
| 25 | 457 |
<a name="id2672613"> |
| 6 | 458 |
</a> |
|
24
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|
459 |
3.Keyword Arguments |
| 6 | 460 |
</h2> |
461 |
</div> |
|
462 |
</div> |
|
463 |
</div> |
|
|
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|
464 |
<p id="ch5func_f"> |
|
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changeset
|
465 |
When a function takes a large number of arguments, it may be difficult to |
|
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|
466 |
remember the order of the parameters in the function definition or it may |
|
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|
467 |
be necessary to pass values to only certain parameters since others take |
|
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|
468 |
the default value. In either of these cases, Python provides the facility |
|
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|
469 |
of passing arguments by specifying the name of the parameter as defined in |
|
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|
470 |
the function definition. This is known as |
|
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|
471 |
<span class="emphasis"> |
|
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changeset
|
472 |
<em> |
|
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changeset
|
473 |
Keyword Arguments |
|
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|
474 |
</em> |
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|
475 |
</span> |
|
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changeset
|
476 |
. |
|
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changeset
|
477 |
</p> |
|
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changeset
|
478 |
<p id="ch5func_10"> |
|
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changeset
|
479 |
In a function call, |
|
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changeset
|
480 |
<span class="emphasis"> |
|
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changeset
|
481 |
<em> |
|
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changeset
|
482 |
Keyword arguments |
|
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changeset
|
483 |
</em> |
|
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changeset
|
484 |
</span> |
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|
485 |
can be used for each argument, in the |
|
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changeset
|
486 |
following fashion: |
|
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changeset
|
487 |
</p> |
|
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|
488 |
<pre class="programlisting"> |
|
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changeset
|
489 |
argument_name=argument_value |
|
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changeset
|
490 |
Also denoted as: keyword=argument |
|
0
8083d21c0020
The first commit of all the required files for the review app
amit@thunder
parents:
diff
changeset
|
491 |
|
|
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|
492 |
def wish(name='World', greetings='Hello'): |
|
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changeset
|
493 |
print "%s, %s!" % (greetings, name) |
|
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changeset
|
494 |
</pre> |
|
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diff
changeset
|
495 |
<p id="ch5func_11"> |
|
10074d1357ff
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amit@thunder
parents:
16
diff
changeset
|
496 |
This function can be called in one of the following ways. It is important to |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
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diff
changeset
|
497 |
note that no restriction is imposed in the order in which |
| 6 | 498 |
<span class="emphasis"> |
499 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
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diff
changeset
|
500 |
Keyword arguments |
|
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Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
501 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
502 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
503 |
can be specified. Also note, that we have combined |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
504 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
505 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
506 |
Keyword arguments |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
507 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
508 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
509 |
with |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
510 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
511 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
512 |
Default arguments |
| 6 | 513 |
</em> |
514 |
</span> |
|
|
24
10074d1357ff
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amit@thunder
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|
515 |
in this example, however it is not necessary: |
| 6 | 516 |
</p> |
|
24
10074d1357ff
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amit@thunder
parents:
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changeset
|
517 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
518 |
wish(name='Guido', greetings='Hey') |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
519 |
wish(greetings='Hey', name='Guido') |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
520 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
521 |
<p id="ch5func_12"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
522 |
Calling functions by specifying arguments in the order of parameters specified |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
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changeset
|
523 |
in the function definition is called as |
| 6 | 524 |
<span class="emphasis"> |
525 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
526 |
Positional arguments |
| 6 | 527 |
</em> |
528 |
</span> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
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changeset
|
529 |
, as opposed to |
| 6 | 530 |
<span class="emphasis"> |
531 |
<em> |
|
|
24
10074d1357ff
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amit@thunder
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16
diff
changeset
|
532 |
Keyword arguments |
|
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Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
533 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
534 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
535 |
. It is possible to use both |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
536 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
537 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
538 |
Positional arguments |
| 6 | 539 |
</em> |
540 |
</span> |
|
541 |
and |
|
542 |
<span class="emphasis"> |
|
543 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
544 |
Keyword arguments |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
545 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
546 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
547 |
in a single function call. But Python doesn't allow us to |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
548 |
bungle up both of them. The arguments to the function, in the call, must always |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
549 |
start with |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
550 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
551 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
552 |
Positional arguments |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
553 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
554 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
555 |
which is in turn followed by |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
556 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
557 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
558 |
Keyword |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
559 |
arguments |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
560 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
561 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
562 |
: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
563 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
564 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
565 |
def my_func(x, y, z, u, v, w): |
|
10074d1357ff
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amit@thunder
parents:
16
diff
changeset
|
566 |
# initialize variables. |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
567 |
... |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
568 |
# do some stuff |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
569 |
... |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
570 |
# return the value |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
571 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
572 |
<p id="ch5func_13"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
573 |
It is valid to call the above functions in the following ways: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
574 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
575 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
576 |
my_func(10, 20, 30, u=1.0, v=2.0, w=3.0) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
577 |
my_func(10, 20, 30, 1.0, 2.0, w=3.0) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
578 |
my_func(10, 20, z=30, u=1.0, v=2.0, w=3.0) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
579 |
my_func(x=10, y=20, z=30, u=1.0, v=2.0, w=3.0) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
580 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
581 |
<p id="ch5func_14"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
582 |
Following lists some of the invalid calls: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
583 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
584 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
585 |
my_func(10, 20, z=30, 1.0, 2.0, 3.0) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
586 |
my_func(x=10, 20, z=30, 1.0, 2.0, 3.0) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
587 |
my_func(x=10, y=20, z=30, u=1.0, v=2.0, 3.0) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
588 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
589 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
590 |
<div class="section" title="4.Parameter Packing and Unpacking"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
591 |
<div class="titlepage"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
592 |
<div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
593 |
<div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
594 |
<h2 class="title" style="clear: both"> |
| 25 | 595 |
<a name="id2672729"> |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
596 |
</a> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
597 |
4.Parameter Packing and Unpacking |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
598 |
</h2> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
599 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
600 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
601 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
602 |
<p id="ch5func_15"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
603 |
The positional arguments passed to a function can be collected in a tuple |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
604 |
parameter and keyword arguments can be collected in a dictionary. Since keyword |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
605 |
arguments must always be the last set of arguments passed to a function, the |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
606 |
keyword dictionary parameter must be the last parameter. The function definition |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
607 |
must include a list explicit parameters, followed by tuple paramter collecting |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
608 |
parameter, whose name is preceded by a |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
609 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
610 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
611 |
* |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
612 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
613 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
614 |
, for collecting positional |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
615 |
parameters, in turn followed by the dictionary collecting parameter, whose name |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
616 |
is preceded by a |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
617 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
618 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
619 |
** |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
620 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
621 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
622 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
623 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
624 |
def print_report(title, *args, **name): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
625 |
"""Structure of *args* |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
626 |
(age, email-id) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
627 |
Structure of *name* |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
628 |
{
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
629 |
'first': First Name |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
630 |
'middle': Middle Name |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
631 |
'last': Last Name |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
632 |
} |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
633 |
""" |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
634 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
635 |
print "Title: %s" % (title) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
636 |
print "Full name: %(first)s %(middle)s %(last)s" % name |
| 25 | 637 |
print "Age: %d nEmail-ID: %s" % args |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
638 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
639 |
<p id="ch5func_16"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
640 |
The above function can be called as. Note, the order of keyword parameters can |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
641 |
be interchanged: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
642 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
643 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
644 |
>>> print_report('Employee Report', 29, 'johny@example.com', first='Johny',
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
645 |
last='Charles', middle='Douglas') |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
646 |
Title: Employee Report |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
647 |
Full name: Johny Douglas Charles |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
648 |
Age: 29 |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
649 |
Email-ID: johny@example.com |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
650 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
651 |
<p id="ch5func_17"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
652 |
The reverse of this can also be achieved by using a very identical syntax while |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
653 |
calling the function. A tuple or a dictionary can be passed as arguments in |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
654 |
place of a list of |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
655 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
656 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
657 |
Positional arguments |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
658 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
659 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
660 |
or |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
661 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
662 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
663 |
Keyword arguments |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
664 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
665 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
666 |
respectively |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
667 |
using |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
668 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
669 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
670 |
* |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
671 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
672 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
673 |
or |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
674 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
675 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
676 |
** |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
677 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
678 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
679 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
680 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
681 |
def print_report(title, age, email, first, middle, last): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
682 |
print "Title: %s" % (title) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
683 |
print "Full name: %s %s %s" % (first, middle, last) |
| 25 | 684 |
print "Age: %d nEmail-ID: %s" % (age, email) |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
685 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
686 |
>>> args = (29, 'johny@example.com') |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
687 |
>>> name = {
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
688 |
'first': 'Johny', |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
689 |
'middle': 'Charles', |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
690 |
'last': 'Douglas' |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
691 |
} |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
692 |
>>> print_report('Employee Report', *args, **name)
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
693 |
Title: Employee Report |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
694 |
Full name: Johny Charles Douglas |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
695 |
Age: 29 |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
696 |
Email-ID: johny@example.com |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
697 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
698 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
699 |
<div class="section" title="5.Nested Functions and Scopes"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
700 |
<div class="titlepage"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
701 |
<div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
702 |
<div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
703 |
<h2 class="title" style="clear: both"> |
| 25 | 704 |
<a name="id2672829"> |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
705 |
</a> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
706 |
5.Nested Functions and Scopes |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
707 |
</h2> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
708 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
709 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
710 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
711 |
<p id="ch5func_18"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
712 |
Python allows nesting one function inside another. This style of programming |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
713 |
turns out to be extremely flexible and powerful features when we use |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
714 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
715 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
716 |
Python |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
717 |
decorators |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
718 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
719 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
720 |
. We will not talk about decorators is beyond the scope of this |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
721 |
course. If you are interested in knowing more about |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
722 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
723 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
724 |
decorator programming |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
725 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
726 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
727 |
in |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
728 |
Python you are suggested to read: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
729 |
</p> |
| 25 | 730 |
<div class="reference"> |
731 |
<div class="titlepage"> |
|
732 |
<hr /> |
|
733 |
</div> |
|
734 |
http://avinashv.net/2008/04/python-decorators-syntactic-sugar/ |
|
735 |
</div> |
|
736 |
<div class="reference"> |
|
737 |
<div class="titlepage"> |
|
738 |
<hr /> |
|
739 |
</div> |
|
740 |
http://personalpages.tds.net/~kent37/kk/00001.html |
|
741 |
</div> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
742 |
<p id="ch5func_19"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
743 |
However, the following is an example for nested functions in Python: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
744 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
745 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
746 |
def outer(): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
747 |
print "Outer..." |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
748 |
def inner(): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
749 |
print "Inner..." |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
750 |
print "Outer..." |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
751 |
inner() |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
752 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
753 |
>>> outer() |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
754 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
755 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
756 |
<div class="section" title="6.map, reduce and filter functions"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
757 |
<div class="titlepage"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
758 |
<div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
759 |
<div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
760 |
<h2 class="title" style="clear: both"> |
| 25 | 761 |
<a name="id2672879"> |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
762 |
</a> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
763 |
6.map, reduce and filter functions |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
764 |
</h2> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
765 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
766 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
767 |
</div> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
768 |
<p id="ch5func_1a"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
769 |
Python provides several built-in functions for convenience. The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
770 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
771 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
772 |
map() |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
773 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
774 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
775 |
, |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
776 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
777 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
778 |
reduce() |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
779 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
780 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
781 |
and |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
782 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
783 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
784 |
filter() |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
785 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
786 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
787 |
functions prove to be very useful with sequences like |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
788 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
789 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
790 |
Lists |
| 6 | 791 |
</em> |
792 |
</span> |
|
793 |
. |
|
794 |
</p> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
795 |
<p id="ch5func_1b"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
796 |
The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
797 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
798 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
799 |
map |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
800 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
801 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
802 |
( |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
803 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
804 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
805 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
806 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
807 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
808 |
, |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
809 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
810 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
811 |
sequence |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
812 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
813 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
814 |
) function takes two arguments: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
815 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
816 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
817 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
818 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
819 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
820 |
and a |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
821 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
822 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
823 |
sequence |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
824 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
825 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
826 |
argument. The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
827 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
828 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
829 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
830 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
831 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
832 |
argument must be the name of the |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
833 |
function which in turn takes a single argument, the individual element of the |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
834 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
835 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
836 |
sequence |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
837 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
838 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
839 |
. The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
840 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
841 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
842 |
map |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
843 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
844 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
845 |
function calls |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
846 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
847 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
848 |
function(item) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
849 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
850 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
851 |
, for each item in the |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
852 |
sequence and returns a list of values, where each value is the value returned |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
853 |
by each call to |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
854 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
855 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
856 |
function(item) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
857 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
858 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
859 |
. |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
860 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
861 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
862 |
map() |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
863 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
864 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
865 |
function allows to pass more than |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
866 |
one sequence. In this case, the first argument, |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
867 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
868 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
869 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
870 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
871 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
872 |
must take as many |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
873 |
arguments as the number of sequences passed. This function is called with each |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
874 |
corresponding element in the each of the sequences, or |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
875 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
876 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
877 |
None |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
878 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
879 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
880 |
if one of the |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
881 |
sequence is exhausted: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
882 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
883 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
884 |
def square(x): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
885 |
return x*x |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
886 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
887 |
>>> map(square, [1, 2, 3, 4]) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
888 |
[1, 4, 9, 16] |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
889 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
890 |
def mul(x, y): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
891 |
return x*y |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
892 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
893 |
>>> map(mul, [1, 2, 3, 4], [6, 7, 8, 9]) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
894 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
895 |
<p id="ch5func_1c"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
896 |
The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
897 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
898 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
899 |
filter |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
900 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
901 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
902 |
( |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
903 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
904 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
905 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
906 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
907 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
908 |
, |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
909 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
910 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
911 |
sequence |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
912 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
913 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
914 |
) function takes two arguments, similar to |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
915 |
the |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
916 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
917 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
918 |
map() |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
919 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
920 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
921 |
function. The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
922 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
923 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
924 |
filter |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
925 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
926 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
927 |
function calls |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
928 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
929 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
930 |
function(item) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
931 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
932 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
933 |
, for each |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
934 |
item in the sequence and returns all the elements in the sequence for which |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
935 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
936 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
937 |
function(item) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
938 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
939 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
940 |
returned True: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
941 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
942 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
943 |
def even(x): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
944 |
if x % 2: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
945 |
return True |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
946 |
else: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
947 |
return False |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
948 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
949 |
>>> filter(even, range(1, 10)) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
950 |
[1, 3, 5, 7, 9] |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
951 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
952 |
<p id="ch5func_1d"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
953 |
The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
954 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
955 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
956 |
reduce |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
957 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
958 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
959 |
( |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
960 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
961 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
962 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
963 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
964 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
965 |
, |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
966 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
967 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
968 |
sequence |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
969 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
970 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
971 |
) function takes two arguments, similar to |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
972 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
973 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
974 |
map |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
975 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
976 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
977 |
function, however multiple sequences are not allowed. The |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
978 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
979 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
980 |
reduce |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
981 |
</strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
982 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
983 |
function calls |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
984 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
985 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
986 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
987 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
988 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
989 |
with first two consecutive elements in the sequence, |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
990 |
obtains the result, calls |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
991 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
992 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
993 |
function |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
994 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
995 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
996 |
with the result and the subsequent element |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
997 |
in the sequence and so on until the end of the list and returns the final result: |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
998 |
</p> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
999 |
<pre class="programlisting"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1000 |
def mul(x, y): |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1001 |
return x*y |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1002 |
|
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1003 |
>>> reduce(mul, [1, 2, 3, 4]) |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1004 |
24 |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1005 |
</pre> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1006 |
<div class="section" title="6.1.List Comprehensions"> |
| 6 | 1007 |
<div class="titlepage"> |
1008 |
<div> |
|
1009 |
<div> |
|
1010 |
<h3 class="title"> |
|
| 25 | 1011 |
<a name="id2673069"> |
| 6 | 1012 |
</a> |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1013 |
6.1.List Comprehensions |
| 6 | 1014 |
</h3> |
1015 |
</div> |
|
1016 |
</div> |
|
1017 |
</div> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1018 |
<p id="ch5func_1e"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1019 |
List Comprehension is a convenvience utility provided by Python. It is a |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1020 |
syntatic sugar to create |
| 6 | 1021 |
<span class="emphasis"> |
1022 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1023 |
Lists |
| 6 | 1024 |
</em> |
1025 |
</span> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1026 |
. Using |
| 6 | 1027 |
<span class="emphasis"> |
1028 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1029 |
List Comprehensions |
| 6 | 1030 |
</em> |
1031 |
</span> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1032 |
one can create |
| 6 | 1033 |
<span class="emphasis"> |
1034 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1035 |
Lists |
| 6 | 1036 |
</em> |
1037 |
</span> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1038 |
from other type of sequential data structures or other |
| 6 | 1039 |
<span class="emphasis"> |
1040 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1041 |
Lists |
| 6 | 1042 |
</em> |
1043 |
</span> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1044 |
itself. |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1045 |
The syntax of |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1046 |
<span class="emphasis"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1047 |
<em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1048 |
List Comprehensions |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1049 |
</em> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1050 |
</span> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1051 |
consists of a square brackets to indicate |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1052 |
the result is a |
| 6 | 1053 |
<span class="emphasis"> |
1054 |
<em> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1055 |
List |
| 6 | 1056 |
</em> |
1057 |
</span> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1058 |
within which we include at least one |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1059 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1060 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1061 |
for |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1062 |
</strong> |
| 6 | 1063 |
</span> |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1064 |
clause and |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1065 |
multiple |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1066 |
<span class="strong"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1067 |
<strong> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1068 |
if |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1069 |
</strong> |
| 6 | 1070 |
</span> |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1071 |
clauses. It will be more clear with an example: |
| 6 | 1072 |
</p> |
1073 |
<pre class="programlisting"> |
|
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1074 |
>>> num = [1, 2, 3] |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1075 |
>>> sq = [x*x for x in num] |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1076 |
>>> sq |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1077 |
[1, 4, 9] |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1078 |
>>> all_num = [1, 2, 3, 4, 5, 6, 7, 8, 9] |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1079 |
>>> even = [x for x in all_num if x%2 == 0] |
| 6 | 1080 |
</pre> |
|
24
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1081 |
<p id="ch5func_1f"> |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1082 |
The syntax used here is very clear from the way it is written. It can be |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1083 |
translated into english as, "for each element x in the list all_num, |
|
10074d1357ff
Some changes after the horrible problem of writing the same ch9 on all the html pages
amit@thunder
parents:
16
diff
changeset
|
1084 |
if remainder of x divided by 2 is 0, add x to the list." |
| 6 | 1085 |
</p> |
1086 |
</div> |
|
1087 |
</div> |
|
1088 |
</div> |
|
1089 |
</div> |
|
1090 |
</body> |
|
|
0
8083d21c0020
The first commit of all the required files for the review app
amit@thunder
parents:
diff
changeset
|
1091 |
</html> |