# HG changeset patch
# User Madhusudan.C.S <madhusudancs@gmail.com>
# Date 1256725413 -19800
# Node ID 238f3010c981d909aedd69a4dad47a7f85ab966b
# Parent  a6705e2dfdc68857f3b22226c38d17f5e35af5a2
Created and made first cut slides for session 2 day 2.

diff -r a6705e2dfdc6 -r 238f3010c981 day2/session2.tex
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/day2/session2.tex	Wed Oct 28 15:53:33 2009 +0530
@@ -0,0 +1,522 @@
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%Tutorial slides on Python.
+%
+% Author: Prabhu Ramachandran <prabhu at aero.iitb.ac.in>
+% Copyright (c) 2005-2009, Prabhu Ramachandran
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+\documentclass[14pt,compress]{beamer}
+%\documentclass[draft]{beamer}
+%\documentclass[compress,handout]{beamer}
+%\usepackage{pgfpages} 
+%\pgfpagesuselayout{2 on 1}[a4paper,border shrink=5mm]
+
+% Modified from: generic-ornate-15min-45min.de.tex
+\mode<presentation>
+{
+  \usetheme{Warsaw}
+  \useoutertheme{split}
+  \setbeamercovered{transparent}
+}
+
+\usepackage[english]{babel}
+\usepackage[latin1]{inputenc}
+%\usepackage{times}
+\usepackage[T1]{fontenc}
+
+% Taken from Fernando's slides.
+\usepackage{ae,aecompl}
+\usepackage{mathpazo,courier,euler}
+\usepackage[scaled=.95]{helvet}
+
+\definecolor{darkgreen}{rgb}{0,0.5,0}
+
+\usepackage{listings}
+\lstset{language=Python,
+    basicstyle=\ttfamily\bfseries,
+    commentstyle=\color{red}\itshape,
+  stringstyle=\color{darkgreen},
+  showstringspaces=false,
+  keywordstyle=\color{blue}\bfseries}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% Macros
+\setbeamercolor{emphbar}{bg=blue!20, fg=black}
+\newcommand{\emphbar}[1]
+{\begin{beamercolorbox}[rounded=true]{emphbar} 
+      {#1}
+ \end{beamercolorbox}
+}
+\newcounter{time}
+\setcounter{time}{0}
+\newcommand{\inctime}[1]{\addtocounter{time}{#1}{\tiny \thetime\ m}}
+
+\newcommand{\typ}[1]{\texttt{#1}}
+
+\newcommand{\kwrd}[1]{ \texttt{\textbf{\color{blue}{#1}}}  }
+
+%%% This is from Fernando's setup.
+% \usepackage{color}
+% \definecolor{orange}{cmyk}{0,0.4,0.8,0.2}
+% % Use and configure listings package for nicely formatted code
+% \usepackage{listings}
+% \lstset{
+%    language=Python,
+%    basicstyle=\small\ttfamily,
+%    commentstyle=\ttfamily\color{blue},
+%    stringstyle=\ttfamily\color{orange},
+%    showstringspaces=false,
+%    breaklines=true,
+%    postbreak = \space\dots
+% }
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% Title page
+\title[Basic Python]{Python:\\A formal approach}
+
+\author[FOSSEE Team] {The FOSSEE Group}
+
+\institute[IIT Bombay] {Department of Aerospace Engineering\\IIT Bombay}
+\date[] {1, November 2009\\Day 2, Session 2}
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+
+%\pgfdeclareimage[height=0.75cm]{iitmlogo}{iitmlogo}
+%\logo{\pgfuseimage{iitmlogo}}
+
+
+%% Delete this, if you do not want the table of contents to pop up at
+%% the beginning of each subsection:
+\AtBeginSubsection[]
+{
+  \begin{frame}<beamer>
+    \frametitle{Outline}
+    \tableofcontents[currentsection,currentsubsection]
+  \end{frame}
+}
+
+\AtBeginSection[]
+{
+  \begin{frame}<beamer>
+    \frametitle{Outline}
+    \tableofcontents[currentsection,currentsubsection]
+  \end{frame}
+}
+
+% If you wish to uncover everything in a step-wise fashion, uncomment
+% the following command: 
+%\beamerdefaultoverlayspecification{<+->}
+
+%\includeonlyframes{current,current1,current2,current3,current4,current5,current6}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+% DOCUMENT STARTS
+\begin{document}
+
+\begin{frame}
+  \titlepage
+\end{frame}
+
+\begin{frame}
+  \frametitle{Outline}
+  \tableofcontents
+  % You might wish to add the option [pausesections]
+\end{frame}
+
+\section{Data structures}
+\subsection{Lists}
+\begin{frame}[fragile]
+  \frametitle{Lists}
+\begin{block}{We already know that}
+  \begin{lstlisting}
+num = [1, 2, 3, 4, 5, 6, 7, 8]
+  \end{lstlisting}
+\centerline{is a list}
+\end{block}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Lists: methods}
+  \begin{lstlisting}
+In []: num.reverse()
+In []: num
+Out[]: [8, 7, 6, 5, 4, 3, 2, 1]
+
+In []: num.extend([0, -1, -2])
+In []: num
+Out[]: [8, 7, 6, 5, 4, 3, 2, 1, 0, -1]
+
+In []: num.remove(0)
+In []: num
+Out[]: [8, 7, 6, 5, 4, 3, 2, 1, -1]
+  \end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{List containership}
+\begin{lstlisting}
+In []: a = 8
+
+In []: a in num
+Out[]: True
+
+In []: b = 10
+In []: b in num
+Out[]: False
+
+In []: b not in num
+Out[]: True
+\end{lstlisting}
+\end{frame}
+
+\subsection{Tuples}
+\begin{frame}[fragile]
+\frametitle{Tuples: Immutable lists}
+\begin{lstlisting}
+In []: t = (1, 2, 3, 4, 5, 6, 7, 8)
+In []: t[0] + t[3] + t[-1]
+Out[]: 13
+\end{lstlisting}
+\begin{block}{Note:}
+\begin{itemize}
+  \item Tuples are immutable - cannot be changed
+\end{itemize}
+\end{block}
+  \inctime{10}
+\end{frame}
+
+\begin{frame}
+  {A classic problem}
+  \begin{block}
+    {Interchange values}
+    How to interchange values of two variables? 
+  \end{block}
+  \pause
+  \begin{block}{Note:}
+    This Python idiom works for all types of variables.\\
+They need not be of the same type!
+  \end{block}
+\end{frame}
+
+\subsection{Dictionaries}
+\begin{frame}[fragile]
+  \frametitle{Dictionaries: Recall}
+  \begin{lstlisting}
+In []: player = {'Mat': 134,'Inn': 233,
+          'Runs': 10823, 'Avg': 52.53}
+
+In []: player['Avg']
+Out[]: 52.530000000000001
+  \end{lstlisting}
+  \begin{block}{Note!}
+    Duplicate keys are not allowed!\\
+    Dictionaries are iterable through keys.
+  \end{block}
+\end{frame}
+
+\begin{frame} {Problem Set 2.1: Problem 2.1.1}
+You are given date strings of the form ``29, Jul 2009'', or ``4 January 2008''. In other words a number a string and another number, with a comma sometimes separating the items.Write a function that takes such a string and returns a tuple (yyyy, mm, dd) where all three elements are ints.
+\end{frame}
+
+\subsection{Set}
+\begin{frame}[fragile]
+  \frametitle{Set}
+    \begin{itemize}
+      \item Simplest container, mutable
+      \item No ordering, no duplicates
+      \item usual suspects: union, intersection, subset \ldots
+      \item >, >=, <, <=, in, \ldots
+    \end{itemize}
+    \begin{lstlisting}
+>>> f10 = set([1,2,3,5,8])
+>>> p10 = set([2,3,5,7])
+>>> f10|p10
+set([1, 2, 3, 5, 7, 8])
+>>> f10&p10
+set([2, 3, 5])
+>>> f10-p10
+set([8, 1])
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Set}
+    \begin{lstlisting}
+>>> p10-f10, f10^p10
+set([7]), set([1, 7, 8])
+>>> set([2,3]) < p10
+True
+>>> set([2,3]) <= p10
+True
+>>> 2 in p10
+True
+>>> 4 in p10
+False
+>>> len(f10)
+5
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}
+  \frametitle{Problem set 2.2}
+  \begin{description}
+    \item[2.2.1] Given a dictionary of the names of students and their marks, identify how many duplicate marks are there? and what are these?
+    \item[2.2.2] Given a string of the form ``4-7, 9, 12, 15'' find the numbers missing in this list for a given range.
+\end{description}
+\inctime{15}
+\end{frame}
+
+\section{Functions}
+\begin{frame}[fragile]
+  \frametitle{Functions}
+  \begin{itemize}
+    \item \kwrd{def} - keyword to define a function
+    \item Arguments are local to a function
+    \item Docstrings are important!
+    \item Functions can return multiple values
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Functions: example}
+  \begin{lstlisting}
+def signum( r ):
+    """returns 0 if r is zero
+    -1 if r is negative
+    +1 if r is positive"""
+    if r < 0:
+        return -1
+    elif r > 0:
+        return 1
+    else:
+        return 0
+  \end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+  {What does this function do?}
+\begin{lstlisting}
+def what( n ):
+    i = 1
+    while i * i < n:
+        i += 1
+    return i * i == n, i
+  \end{lstlisting}
+\end{frame}
+
+\subsection{Default arguments}
+\begin{frame}[fragile]
+  \frametitle{Functions: default arguments}
+  \small
+  \begin{lstlisting}
+def ask_ok(prompt, complaint='Yes or no!'):
+    while True:
+        ok = raw_input(prompt)
+        if ok in ('y', 'ye', 'yes'): 
+            return True
+        if ok in ('n', 'no', 'nop',
+                  'nope'): 
+            return False
+        print complaint
+
+ask_ok('?')
+ask_ok('?', '[Y/N]')
+  \end{lstlisting}
+\end{frame}
+
+\subsection{Built-in functions}
+\begin{frame}
+  {Before writing a function}
+  \begin{itemize}
+      \item Variety of builtin functions are available
+      \item \typ{abs, any, all, len, max, min}
+      \item \typ{pow, range, sum, type}
+      \item Refer here:
+          \url{http://docs.python.org/library/functions.html}
+  \end{itemize}
+  \inctime{10} 
+\end{frame}
+
+\subsection{Exercises}
+\begin{frame}{Problem set 3: Problem 3.1}
+  Write a function to return the gcd of two numbers.
+\end{frame}
+
+\begin{frame}{Problem 3.2}
+Write a program to print all primitive pythagorean triads (a, b, c) where a, b are in the range 1---100 \\
+A pythagorean triad $(a,b,c)$ has the property $a^2 + b^2 = c^2$.\\By primitive we mean triads that do not `depend' on others. For example, (4,3,5) is a variant of (3,4,5) and hence is not primitive. And (10,24,26) is easily derived from (5,12,13) and is also not primitive.
+\end{frame}
+
+\begin{frame}{Problem 3.3}
+  Write a program that generates a list of all four digit numbers that have all their digits even and are perfect squares.\newline\\\emph{For example, the output should include 6400 but not 8100 (one digit is odd) or 4248 (not a perfect square).}
+\inctime{15}
+\end{frame}
+
+\section{Modules}
+\begin{frame}[fragile]
+    {Modules}
+\begin{lstlisting}
+>>> sqrt(2)
+Traceback (most recent call last):
+  File "<stdin>", line 1, in <module>
+NameError: name 'sqrt' is not defined
+>>> import math        
+>>> math.sqrt(2)
+1.4142135623730951
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+    {Modules}
+  \begin{itemize}
+    \item The \kwrd{import} keyword ``loads'' a module
+    \item One can also use:
+      \begin{lstlisting}
+>>> from math import sqrt
+>>> from math import *
+      \end{lstlisting}    
+    \item What is the difference?
+    \item \alert{Use the latter only in interactive mode}
+    \end{itemize}
+  \emphbar{Package hierarchies}
+      \begin{lstlisting}
+>>> from os.path import exists
+      \end{lstlisting}
+\end{frame}
+
+\begin{frame}
+  \frametitle{Modules: Standard library}
+  \begin{itemize}
+  \item Very powerful, ``Batteries included''
+  \item Some standard modules:
+    \begin{itemize}
+    \item Math: \typ{math}, \typ{random}
+    \item Internet access: \typ{urllib2}, \typ{smtplib}
+    \item System, Command line arguments: \typ{sys}
+    \item Operating system interface: \typ{os}
+    \item Regular expressions: \typ{re}
+    \item Compression: \typ{gzip}, \typ{zipfile}, and \typ{tarfile}
+    \item And a whole lot more!
+    \end{itemize}
+  \item Check out the Python Library reference:
+    \url{http://docs.python.org/library/}
+  \end{itemize}
+\inctime{5}
+\end{frame}
+
+\section{Coding Style}
+\begin{frame}{Readability and Consistency}
+    \begin{itemize}
+        \item Readability Counts!\\Code is read more often than its written.
+        \item Consistency!
+        \item Know when to be inconsistent.
+      \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile] \frametitle{A question of good style}
+  \begin{lstlisting}
+    amount = 12.68
+    denom = 0.05
+    nCoins = round(amount/denom)
+    rAmount = nCoins * denom
+  \end{lstlisting}
+  \pause
+  \begin{block}{Style Rule \#1}
+    Naming is 80\% of programming
+  \end{block}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Code Layout}
+  \begin{itemize}
+        \item Indentation
+        \item Tabs or Spaces??
+        \item Maximum Line Length
+        \item Blank Lines
+        \item Encodings
+   \end{itemize}
+\end{frame}
+
+\begin{frame}{Whitespaces in Expressions}
+  \begin{itemize}
+        \item When to use extraneous whitespaces??
+        \item When to avoid extra whitespaces??
+        \item Use one statement per line
+   \end{itemize}
+\end{frame}
+
+\begin{frame}{Comments}
+  \begin{itemize}
+        \item No comments better than contradicting comments
+        \item Block comments
+        \item Inline comments
+   \end{itemize}
+\end{frame}
+
+\begin{frame}{Docstrings}
+  \begin{itemize}
+        \item When to write docstrings?
+        \item Ending the docstrings
+        \item One liner docstrings
+   \end{itemize}
+More information at PEP8: http://www.python.org/dev/peps/pep-0008/
+\inctime{5}
+\end{frame}
+
+\section{Objects}
+\begin{frame}{Objects in general}
+    \begin{itemize}
+        \item What is an Object? (Types and classes)
+        \item identity
+        \item type
+        \item method
+      \end{itemize}
+\end{frame}
+
+\begin{frame}{Almost everything is an Object!}
+  \begin{itemize}
+    \item \typ{list}
+    \item \typ{tuple}
+    \item \typ{string}
+    \item \typ{dictionary}
+    \item \typ{function}
+    \item Of course, user defined class objects!
+  \end{itemize}
+\end {frame}
+
+\begin{frame}{Using Objects}
+  \begin{itemize}
+    \item Creating Objects: Initialization
+    \item Object Manipulation: Object methods and ``.'' operator
+  \end{itemize}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Objects provide consistency}
+  \small
+  \begin{lstlisting}
+for element in (1, 2, 3):
+    print element
+for key in {'one':1, 'two':2}:
+    print key
+for char in "123":
+    print char
+for line in open("myfile.txt"):
+    print line
+for line in urllib2.urlopen('http://site.com'):
+    print line
+  \end{lstlisting}
+\inctime{10}
+\end{frame}
+
+\begin{frame}
+  \frametitle{What did we learn?}
+  \begin{itemize}
+    \item Lists, Tuples, Dictionaries, Sets: creation and manipulation
+    \item More about functions
+    \item Coding style
+    \item Objects: creation and manipulation
+  \end{itemize}
+\end{frame}
+
+\end{document}