path: root/day2/session1.tex

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Tutorial slides on Python.
%
% Author: Prabhu Ramachandran <prabhu at aero.iitb.ac.in>
% Copyright (c) 2005-2009, Prabhu Ramachandran
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\usepackage{listings}
\lstset{language=Python,
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    commentstyle=\color{red}\itshape,
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% 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 1}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

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%% 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}
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    \frametitle{Outline}
    \tableofcontents[currentsection,currentsubsection]
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% 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 types}

\begin{frame}
  \frametitle{Primitive Data types}
  \begin{itemize}
    \item Numbers: float, int, complex
    \item Strings
    \item Boolean
  \end{itemize}
\end{frame}

\subsection{Numbers}
\begin{frame}[fragile]
  \frametitle{Numbers}
  \begin{itemize}
    \item \kwrd{int}\\ Any whole number is an \kwrd{int}, no matter what the size!
  \begin{lstlisting}
In []: a = 13

In []: a = 99999999999999999999
  \end{lstlisting}
    \item \kwrd{float}
  \begin{lstlisting}
In []: fl = 3.141592
  \end{lstlisting}
  \end{itemize}
\end{frame}

\begin{frame}[fragile]
\frametitle{Complex numbers}
  \begin{lstlisting}
In []: cplx = 3+4j

In []: abs(cplx)
Out[]: 5.0

In []: cplx.imag
Out[]: 4.0

In []: cplx.real
Out[]: 3.0
  \end{lstlisting}
\end{frame}

\subsection{Boolean}
\begin{frame}{Boolean}
  \begin{itemize}
    \item \kwrd{True}
    \item \kwrd{False}
    \item \kwrd{not}
    \item \kwrd{and}
    \item \kwrd{or}
  \end{itemize}
\end{frame}

\subsection{Strings}
\begin{frame}[fragile]
  \frametitle{String methods}
Strings were introduced previously, let us now look at them in a little more detail.
  \begin{lstlisting}
In []: a = 'hello world'

In []: a.startswith('hell')
Out[]: True

In []: a.endswith('ld')
Out[]: True
  \end{lstlisting}
\end{frame}

\begin{frame}[fragile]
\frametitle{Still with strings}
We saw split() previously. join() is the opposite of split()
  \begin{lstlisting}
In []: ''.join(['a', 'b', 'c'])
Out[]: 'abc'
  \end{lstlisting}
  \begin{block}{Note:}
Strings are immutable.\\ That is string variables cannot be changed.
  \end{block}
\end{frame}

\begin{frame}[fragile]
\frametitle{String formatting}
  \begin{lstlisting}
In []: x, y = 1, 1.234
In []: 'x is %s, y is %s' %(x, y)
Out[]: 'x is 1, y is 1.234'
  \end{lstlisting}
  \small
\url{docs.python.org/lib/typesseq-strings.html}\\
\inctime{10}
\end{frame}

\section{Relational and logical operators}
\begin{frame}[fragile]
  \frametitle{Relational and logical operators}
  \begin{lstlisting}
In []: pos, zer, neg = 1, 0, -1
In []: pos == neg
Out[]: False

In []: pos >= neg
Out[]: True

In []: neg < zer < pos
Out[]: True

In []: pos + neg != zer
Out[]: False
  \end{lstlisting}
\inctime{5}
\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}
  \inctime{}
\end{frame}

\section{Control flow}
\begin{frame}
  \frametitle{Control flow constructs}  
  \begin{itemize}
  \item \kwrd{if/elif/else}: branching
  \item \kwrd{while}: looping
  \item \kwrd{for}: iterating 
  \item \kwrd{break, continue}: modify loop 
  \item \kwrd{pass}: syntactic filler
  \end{itemize}
\end{frame}

\subsection{Basic Conditional flow}
\begin{frame}[fragile]
  \frametitle{\typ{If...elif...else} example}
\begin{lstlisting}
x = int(raw_input("Enter an integer:"))
if x < 0:
     print 'Be positive!'
elif x == 0:
     print 'Zero'
elif x == 1:
     print 'Single'
else:
     print 'More'
\end{lstlisting}
\end{frame}

\begin{frame}{Simple IO}
  \begin{block}
    {Console Input}
    \texttt{raw\_input()} waits for user input.\\Prompt string is optional.\\
    All keystrokes are Strings!\\\texttt{int()} converts string to int.
  \end{block}
  \begin{block}
    {Console output}
    \texttt{print} is straight forward. Note the distinction between \texttt{print x} and \texttt{print x,}
  \end{block}
\end{frame}

\subsection{Basic Looping}
\begin{frame}[fragile]
  \frametitle{\kwrd{while}}
Example: Fibonacci series
  \begin{lstlisting}
# the sum of two elements
# defines the next
a, b = 0, 1
while b < 10:
    print b,
    a, b = b, a + b 
\end{lstlisting}
\typ{1 1 2 3 5 8}\\  
\end{frame}

\begin{frame}[fragile]
\frametitle{\kwrd{range()}}
\kwrd{range([start,] stop[, step])}\\
\begin{itemize}
  \item \alert {range() returns a list of integers}
  \item \alert {The start and the step arguments are optional}  
\end{itemize}
\end{frame}

\begin{frame}[fragile]
  \frametitle{\kwrd{for}}
Example: print squares of first \typ{n} numbers
  \begin{lstlisting}
In []: for i in range(5):
 ....:     print i, i * i
 ....:     
 ....:     
0 0
1 1
2 4
3 9
4 16
\end{lstlisting}
\inctime{15}
\end{frame}

\section{Lists}
\begin{frame}[fragile]
\frametitle{More List methods}
\begin{lstlisting}
In []: lst = [1,2,3,4,5,6,7,8]
In []: lst.reverse()
In []: lst
Out[]: [8, 7, 6, 5, 4, 3, 2, 1]

In []: lst.extend([0, -1, -2])
In []: lst
Out[]: [8, 7, 6, 5, 4, 3, 2, 1, 0, -1]

In []: lst.remove(0)
In []: lst
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 lst
Out[]: True

In []: b = 10
In []: b in lst
Out[]: False

In []: b not in lst
Out[]: True
\end{lstlisting}
\inctime{10}
\end{frame}

\section{Tuples}
\begin{frame}[fragile]
\frametitle{Tuples: Immutable lists}
\begin{lstlisting}
In []: tup = (1,2,3,4,5,6,7,8)
In []: tup[0]+tup[3]+tup[-1]
Out[]: 13
\end{lstlisting}
\begin{block}{Note:}
\begin{itemize}
\item Tuples are immutable - cannot be changed
\item Multiple return values in a function are actually tuples
\item Tuples are working behind the scenes in exchanging values - Tuple Unpacking
\end{itemize}
\end{block}
\inctime{5}
\end{frame}

\section{Dictionaries}
\begin{frame}[fragile]
\frametitle{Dictionaries}
  \alert {lists and tuples: integer indexes :: dictionaries: string indexes}
\begin{lstlisting}
In []: player = {'Mat': 134,'Inn': 233, 
           'Runs': 10823, 'Avg': 52.53}

In []: player['Avg']
Out[]: 52.530000000000001
In []: player.keys()
Out[]: ['Runs', 'Inn', 'Avg', 'Mat']
In []: player.values()
Out[]: [10823, 233, 
       52.530000000000001, 134]
\end{lstlisting}
\end{frame}

\begin{frame}{Dictionaries}
\begin{itemize}
\item Duplicate keys are not allowed!
\item Dictionaries are iterable through keys.
\end{itemize}
\inctime{5}
\end{frame}

\end{document}