getting-started-with-for/slides.org
author anand
Mon, 08 Nov 2010 01:36:47 +0530
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#+TITLE: Getting started with for
#+AUTHOR: FOSSEE
#+EMAIL:     
#+DATE:    

#+DESCRIPTION: 
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#+LANGUAGE:  en
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* Outline
  - ~for~ loop in Python.
  - Blocks of code in Python.
    - Indentation
* Whitespace in Python
  - Whitespace is significant
    - blocks are visually separated
  - Blocks are indented using 4 spaces
    : Block A
    : Block A
    :     Block B
    :     Block B
    : Block A
    ~Block B~ is an inner block and is indented using 4 spaces
* Exercise 1
  Write a ~for~ loop which iterates through a list of numbers and find
  the square root of each number.
  : 
  The numbers are,
  : 1369, 7225, 3364, 7056, 5625, 729, 7056, 
  : 576, 2916
* Solution 1
  - Open text editor and type the following code
  #+begin_src python
    numbers = [1369, 7225, 3364, 7056, 5625, 729, 7056, 
               576, 2916]

    for each in numbers:
        print "Square root of", each, "is", sqrt(each)

    print "This is not in for loop!"
  #+end_src
* Save \& run script
  - Save the script as ~list_roots.py~
  - Run in ~ipython~ interpreter as,
    : In []: %run -i list_roots.py
* Exercise 2
  From the given numbers make a list of perfect squares and a list of those which are not.
  : 
  The numbers are,
  : 7225, 3268, 3364, 2966, 7056, 5625, 729, 5547, 
  : 7056, 576, 2916
* Exercise 3 (indentation in ~ipython~)
  Print the square root of numbers in the list.
  : 
  Numbers are,
  : 7225, 3268, 3364, 2966, 7056, 5625, 729, 5547, 
  : 7056, 576, 2916
* Indentation in ~ipython~
  : In []: numbers = [1369, 7225, 3364, 7056, 5625, 
  :   ...:  729, 7056, 576, 2916]

  : In []: for each in numbers:
  :   ...:     
  Note the four spaces here
  : 
  : 
  : 
  : 
  : 
  : 
* Indentation in ~ipython~ (cont'd)
  : In []: numbers = [1369, 7225, 3364, 7056, 5625, 
  :   ...:  729, 7056, 576, 2916]
  : In []: for each in numbers:
  :   ...:     
  Note the four spaces here
  : 
  Now type the rest of the code
  :   ...:     print "Square root of", each, 
  :   ...:     print "is", sqrt(each)
  :   ...:     
  :   ...:     
* Indentation in ~python~ interpreter
  Find out the cube of all the numbers from 1 to 10.
  : 
  /do it in the python interpreter/
* Indentation in ~python~ interpreter (cont'd)
  #+begin_src python
  >>> for i in range(1, 11):
  ...     print i, "cube is", i**3
  ... 
  #+end_src
* ~range()~ function
  - in built function in Python
  - generates a list of integers
    - /syntax:/ range([start,] stop[, step])
    - /example:/
      - range(1, 20) - /generates integers from 1 to 20/
      - range(20) - /generates integers from 0 to 20/
* Exercise 4
  Print all the odd numbers from 1 to 50.
* Summary
  - blocks in ~python~
  - indentation
  - blocks in ~ipython~ interpreter
  - ~for~ loop
  - iterating over list using ~for~ loop
  - ~range()~ function
* Thank you!
#+begin_latex
  \begin{block}{}
  \begin{center}
  This spoken tutorial has been produced by the
  \textcolor{blue}{FOSSEE} team, which is funded by the 
  \end{center}
  \begin{center}
    \textcolor{blue}{National Mission on Education through \\
      Information \& Communication Technology \\ 
      MHRD, Govt. of India}.
  \end{center}  
  \end{block}
#+end_latex