% Created 2010-10-12 Tue 17:12

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\title{Using python modules}

\author{FOSSEE}

\date{}

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\begin{document}

\maketitle

\begin{frame}

\frametitle{Outline}

\label{sec-1}

\begin{itemize}

\item Running python scripts from command line

\item Importing python modules

\item Importing scipy \& pylab modules

\item About python standard library.

\end{itemize}

\end{frame}

\begin{frame}[fragile]

\frametitle{Running Python script from command line}

\label{sec-2}

\begin{itemize}

\item Create a script, open text editor and type the following

\begin{verbatim}

     print "hello world!"

     print

\end{verbatim}

\item Save the script as \texttt{hello.py}

\end{itemize}

\end{frame}

\begin{frame}[fragile]

\frametitle{Running Python script from command line (cont'd)}

\label{sec-3}

\begin{itemize}

\item Run the script

\begin{verbatim}

     $ python hello.py

\end{verbatim}

\end{itemize}

  \emph{Syntax :} \textbf{python filename}

\end{frame}

\begin{frame}

\frametitle{Four plot problem}

\label{sec-4}

    \begin{center}

      \includegraphics[scale=0.4]{four_plot}    

    \end{center}

\end{frame}

\begin{frame}[fragile]

\frametitle{Fix \texttt{linspace()} problem}

\label{sec-5}

\begin{verbatim}

   from scipy import *

\end{verbatim}

\end{frame}

\begin{frame}[fragile]

\frametitle{Fix \texttt{plot()} problem}

\label{sec-6}

\begin{verbatim}

   from pylab import *

\end{verbatim}

\end{frame}

\begin{frame}[fragile]

\frametitle{Better way of fixing}

\label{sec-7}

\begin{verbatim}

   from scipy import linspace

\end{verbatim}

  instead of

\begin{verbatim}

   from scipy import *

\end{verbatim}

    \texttt{*} means import all functions from name-space \texttt{scipy}.

\end{frame}

\begin{frame}[fragile]

\frametitle{Instead of \texttt{*}}

\label{sec-8}

\begin{verbatim}

    from scipy import linspace, pi, sin

    from pylab import plot, legend, annotate

    from pylab import xlim, ylim, title, show

\end{verbatim}

  Is better than, \texttt{from scipy import *} \& \texttt{from pylab import *}.

\end{frame}

\begin{frame}[fragile]

\frametitle{Another Fix}

\label{sec-9}

\begin{verbatim}

import scipy

import pylab

x = scipy.linspace(-5*scipy.pi, 5*scipy.pi, 500)

pylab.plot(x, x, 'b')

pylab.plot(x, -x, 'b')

pylab.plot(x, scipy.sin(x), 'g', linewidth=2)

pylab.plot(x, x*scipy.sin(x), 'r', linewidth=3)

pylab.legend(['x', '-x', 'sin(x)', 'xsin(x)'])

pylab.annotate('origin', xy = (0, 0))

pylab.xlim(-5*scipy.pi, 5*scipy.pi)

pylab.ylim(-5*scipy.pi, 5*scipy.pi)

\end{verbatim}

\end{frame}

\begin{frame}

\frametitle{Exercise 1}

\label{sec-10}

  Write a python script to plot a sine wave from 

    $-2\Pi$

  to 

    $2\Pi$

  .

\end{frame}

\begin{frame}

\frametitle{What is a module?}

\label{sec-11}

  Module is simply a file containing Python definitions and

  statements. Definitions from a module can be imported into other

  modules or into the main module.

\end{frame}

\begin{frame}

\frametitle{Python standard library}

\label{sec-12}

  Python has a very rich standard library of modules.

\begin{itemize}

\item Few libraries

\begin{itemize}

\item Math: \texttt{math}, \texttt{random}

\item Internet access: \texttt{urllib2}, \texttt{smtplib}

\item System, Command line arguments: \texttt{sys}

\item Operating system interface: \texttt{os}

\item regular expressions: \texttt{re}

\item compression: \texttt{gzip}, \texttt{zipfile}, \texttt{tarfile}

\end{itemize}

\item More information

\begin{itemize}

\item \href{http://docs.python.org/library}{http://docs.python.org/library}

\end{itemize}

\end{itemize}

\end{frame}

\begin{frame}

\frametitle{Summary}

\label{sec-13}

\begin{itemize}

\item Running scripts from command line

\item Learned about modules

\begin{itemize}

\item importing modules

\end{itemize}

\item Python standard library

\end{itemize}

\end{frame}

\begin{frame}

\frametitle{Thank you!}

\label{sec-14}

  \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{frame}

\end{document}