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#+TITLE: Using python modules

#+AUTHOR: FOSSEE

#+EMAIL:     

#+DATE:    

#+DESCRIPTION: 

#+KEYWORDS: 

#+LANGUAGE:  en

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* Outline

  - Running python scripts from command line

  - Importing python modules

  - Importing scipy \& pylab modules

  - About python standard library.

* Running Python script from command line

  - Create a script, open text editor and type the following

    : print "hello world!"

    : print 

  - Save the script as ~hello.py~

* Running Python script from command line (cont'd)

  - Run the script

    : $ python hello.py

  /Syntax :/ *python filename*

* Four plot problem

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    \begin{center}

      \includegraphics[scale=0.4]{four_plot}    

    \end{center}

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* Fix ~linspace()~ problem

  : from scipy import *

* Fix ~plot()~ problem

  : from pylab import *

* Better way of fixing

  : from scipy import linspace

  instead of

  : from scipy import *

    ~*~ means import all functions from name-space ~scipy~.

* Instead of ~*~

  :  from scipy import linspace, pi, sin

  :  from pylab import plot, legend, annotate

  :  from pylab import xlim, ylim, title, show

  Is better than, ~from scipy import *~ \& ~from pylab import *~.

* Another Fix

  #+begin_src python

    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_src

* Exercise 1

  Write a python script to plot a sine wave from 

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    $-2\Pi$

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  to 

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    $2\Pi$

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  .

* What is a module?

  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.

* Python standard library

  Python has a very rich standard library of modules.

  - Few libraries

    - Math: ~math~, ~random~

    - Internet access: ~urllib2~, ~smtplib~

    - System, Command line arguments: ~sys~

    - Operating system interface: ~os~

    - regular expressions: ~re~

    - compression: ~gzip~, ~zipfile~, ~tarfile~

  - More information

    - [[http://docs.python.org/library]]

* Summary

  - Running scripts from command line

  - Learned about modules

    - importing modules

  - Python standard library

* Thank you!

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  \begin{block}{}

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  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}

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