--- a/using python modules/script.rst Wed Nov 17 23:24:57 2010 +0530
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,247 +0,0 @@
-.. Objectives
-.. ----------
-
-.. At the end of this tutorial, you will be able to
-
-.. 1. Execute python scripts from command line.
-.. #. Use import in scripts.
-.. #. Import scipy and pylab modules
-.. #. Use python standard modules and 3rd party modules.
-
-
-.. Prerequisites
-.. -------------
-
-.. 1. should have ``pylab`` installed.
-.. #. using plot command interactively.
-.. #. embellishing a plot.
-.. #. saving plots.
-
-.. Author : Anoop Jacob Thomas <anoop@fossee.in>
- Internal Reviewer : Puneeth
- External Reviewer :
- Language Reviewer : Bhanukiran
- Checklist OK? : <11-11-2010, Anand, OK> [2010-10-05]
-
-
-====================
-Using Python modules
-====================
-{{{ show the welcome slide }}}
-
-Welcome to the spoken tutorial on Using Python Modules.
-
-{{{ switch to next slide, outline slide }}}
-
-In this tutorial, we will see how to run python scripts from command
-line. We'll see how to import modules, importing scipy and pylab
-modules and have a look at the Python standard library.
-
-{{{ switch to next slide on executing python scripts from command line }}}
-
-Let us create a simple python script to print hello world. Open your
-text editor and type the following,
-
-{{{ open the text editor and type the following }}}
-::
-
- print "Hello world!"
- print
-
-and save the script as ``hello.py``,
-
-{{{ save the script as hello.py }}}
-
-Till now we saw how to run a script using the IPython interpreter
-using the
-::
-
- %run -i hello.py
-
-option, but that is not the correct way of running a python
-script.
-
-The correct method is to run it using the Python interpreter. Open the
-terminal and navigate to the directory where hello.py is,
-
-{{{ open terminal and navigate to directory where hello.py was saved }}}
-
-{{{ switch to next slide }}}
-
-now run the Python script as,
-::
-
- python hello.py
-
-It executed the script and we got the output ``Hello World!``.
-
-{{{ highlight ``python filename`` syntax on slide while narrating }}}
-
-The syntax is python space filename.
-
-{{{ switch to next slide, four plot problem }}}
-
-Now recall the four plot problem where we plotted four plots in a single
-figure. Let us run that script from command line.
-
-If you don't have the script,
-
-{{{ open the four_plot.py file in text editor }}}
-
-just pause here and create a python script with the following lines
-and save it as four_plot.py.
-
-Now let us run four_plot.py as a python script.
-::
-
- python four_plot.py
-
-Oops! even though it was supposed to work, it didn't. It gave an error
-``linspace()`` is not defined, which means that the function
-``linspace()`` is not available in the current name-space.
-
-But if you try to run the same script using ``%run -i four_plot.py``
-in your IPython interpreter started with the option ``-pylab`` it will
-work, because the ``-pylab`` option does some work for us by importing
-the required modules to our name-space when ipython interpreter
-starts. And thus we don't have to explicitly import modules.
-
-So now let us try to fix the problem and run the script in command
-line,
-
-{{{ switch to next slide, fix ``linspace`` problem }}}
-
-add the following line as the first line in the script,
-{{{ add the line as first line in four_plot.py and save }}}
-::
-
- from scipy import *
-
-Now let us run the script again,
-::
-
- python four_plot.py
-
-Now it gave another error -- plot not defined, let us edit the file
-again and add the line below the line we just added,
-
-{{{ switch to next slide, fix ``plot`` problem }}}
-
-{{{ add the line as second line in four_plot.py and save }}}
-::
-
- from pylab import *
-
-And run the script,
-::
-
- python four_plot.py
-
-Yes! it worked. So what did we do?
-
-We actually imported the required modules using the keyword ``import``.
-It could have also be done as,
-
-{{{ switch to next slide, better way of fixing }}}
-
-{{{ highlight the following in slide and say it loud }}}
-::
-
- from scipy import linspace
-
-instead of,
-::
-
- from scipy import *
-
-So in practice it is always good to use function names instead of
-asterisk or star. If we use asterisk to import from a particular
-module then it will replace any existing functions with the same name
-in our name-space.
-
-{{{ switch to next slide, Instead of ``*`` }}}
-
-So let us modify four_plot.py as,
-{{{ delete the first two lines and add the following }}}
-::
-
- from scipy import linspace, pi, sin
- from pylab import plot, legend, annotate
- from pylab import xlim, ylim, title, show
-
-Now let us try running the code again as,
-::
-
- python four_plot.py
-
-It works! In this method we actually imported the functions to the
-current name-space, and there is another method of doing it. And that
-is,
-
-{{{ switch to next slide }}}
-
-Notice that we use ``scipy.pi`` instead of just ``pi`` as in the
-previous method, and the functions are called as ``pylab.plot()`` and
-``pylab.annotate()`` and not as ``plot()`` and ``annotate()``.
-
-{{{ switch to next slide, problem statement }}}
-
-%% %% Write a script to plot a sine wave from minus two pi to two pi.
-
-Pause here and try to solve the problem yourself before looking at the
-solution.
-
-It can solved as,
-
-{{{ open sine.py and show it }}}
-
-the first line we import the required functions ``linspace()`` and
-``sin()`` and constant ``pi`` from the module scipy. the second and
-third line we import the functions ``plot()``, ``legend()``,
-``show()``, ``title()``, ``xlabel()`` and ``ylabel()``. And the rest
-the code to generate the plot.
-
-We can run it as,
-{{{ now switch focus to terminal and run the script }}}
-::
-
- python sine.py
-
-{{{ switch to next slide, What is a module? }}}
-
-Until now we have been learning about importing modules, now what is a
-module?
-
-A 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.
-
-{{{ switch to next slide, Python standard library }}}
-
-Python has a very rich standard library of modules. It is very
-extensive, offering a wide range of facilities. Some of the standard
-modules are,
-
-for Math: math, random
-for Internet access: urllib2, smtplib
-for System, Command line arguments: sys
-for Operating system interface: os
-for regular expressions: re
-for compression: gzip, zipfile, tarfile
-And there are lot more.
-
-Find more information at Python Library reference,
-``http://docs.python.org/library/``
-
-There are a lot of other modules like pylab, scipy, Mayavi, etc which
-are not part of the standard python library.
-
-{{{ switch to next slide, summary }}}
-
-This brings us to the end of this tutorial, in this tutorial we
-learned running scripts from command line, learned about modules, saw
-the python standard library.
-
-{{{ switch to next slide, thank you slide }}}
-
-Thank you!