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#+TITLE: Using python modules
#+AUTHOR: FOSSEE
#+EMAIL:     
#+DATE:    

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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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  This spoken tutorial has been produced by the
  \textcolor{blue}{FOSSEE} team, which is funded by the 
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  \begin{center}
    \textcolor{blue}{National Mission on Education through \\
      Information \& Communication Technology \\ 
      MHRD, Govt. of India}.
  \end{center}  
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