.. Objectives
.. ----------

.. At the end of this tutorial, you will be able to 

.. 1. Save plots using ``savefig()`` function.
.. #. Save plots in different formats.


.. Prerequisites
.. -------------

..   1. should have ``ipython`` and ``pylab`` installed. 
..   #. getting started with ``ipython``.
..   #. using plot command interactively.
     
.. Author              : Anoop Jacob Thomas <anoop@fossee.in>
   Internal Reviewer   : Puneeth
   External Reviewer   :
   Language Reviewer   : Bhanukiran
   Checklist OK?       : <10-11-2010, Anand, OK> [2010-10-05]

.. #[Puneeth: Quickref missing.]

=======
Script
=======
.. L1

{{{ Show the first slide containing title, name of the production
team along with the logo of MHRD }}}

.. R1

Hello and welcome to the tutorial on "Saving plots".

.. L2

{{{ Show slide with objectives }}}

.. R2

At the end of this tutorial, you will be able to,

 1. Save plots using ``savefig()`` function.
 #. Save plots in different formats.  

.. R3

Before beginning this tutorial,we would suggest you to complete the 
tutorial on "Using plot interactively".

Start your IPython interpreter with the command 
ipython -pylab
<Pause>

As you know, it will start your IPython interpreter with the required
python modules for plotting and saving your plots.

.. L3

{{{ Show slide with pre-requisite }}}

{{{ Shift to terminal and start ipython -pylab }}}

::

    ipython -pylab

.. L4

{{{Switch to slide 'Creating a basic plot'}}}

.. R4

To start with, let us plot a sine wave from minus 3 pi to 3 pi.
Let us start by calculating the required points for the plot. It
can be done using linspace as, 

.. L5

::

    x = linspace(-3*pi,3*pi,100)

.. R5

We have stored the required points in x. Now let us plot the points using
the plot statement. 

.. L6

::

    plot(x,sin(x))

{{{ Keep the plot open }}}

.. R6

Done! we have made a very basic sine plot, now let us see how to save
the plot for future use so that you can embed the plot in your
reports.

.. L7

{{{ switch to next slide, savefig() }}}

.. R7

For saving the plot, we will use ``savefig()`` function.For this we shall 
keep the plot window open alongside the terminal. The statement is, 

.. L8

{{{ Switch the focus to IPython interpreter window }}}

::

    savefig('/home/fossee/sine.png')

.. R8

Notice that ``savefig`` function takes one argument which is the
filename. The last 3 characters after the ``.`` in the filename is the
extension or type of the file which determines the format in which you
want to save.

.. L9

{{{ Highlight the /home/fossee part using mouse movements }}}

.. R9

Also, note that we gave the full path or the absolute path to which we
want to save the file.

.. L10

{{{ Highlight the .png part using mouse movements }}}

.. R10

Here we have used an extension ``.png`` which means we want to save the
image as a PNG file.

Now let us locate the file ``sine.png`` which we had saved a while ago.
We have saved the file to ``/home/fossee`` so let us navigate to 
``/home/fossee`` using thefile browser.

.. L11

{{{ Open the browser, navigate to /home/fossee and highlight the file
sine.png }}}

.. R11

Yes, the file ``sine.png`` is here.let us open it and check.

.. L12

{{{ Open the file sine.png and show it for two-three seconds and then
close it and return to IPython interpreter, make sure the plot window
is still open, also don't close the file browser window }}}

{{{ switch to next slide, More on savefig() }}}

.. R12

So in-order to save a plot, we use ``savefig`` function. ``savefig``
can save the plot in many formats, such as pdf - portable document
format, ps - post script, eps - encapsulated post script, svg -
scalable vector graphics, png - portable network graphics which
support transparency etc.

.. L13

{{{ switch to next slide,'exercise 1' }}}

.. R13

Pause the video here, try out the following exercise and resume the video.

Save the sine plot in the EPS format which can be embedded in 
LaTeX documents.

.. L14

{{{ Switch focus to the already open plot window }}}

.. R14

We still have the sine plot with us,let us now save the plot as
``sine.eps``.

.. L15

{{{ Switch focus to IPython interpreter }}}

.. R15

Now, We will save the plot using the function ``savefig``

.. L16

::

    savefig('/home/fossee/sine.eps')

{{{ Switch focus to file browser window }}}

.. R16

Now let us go to ``/home/fossee`` and see the new file created.

.. L17

{{{ Highlight the file sine.eps for 2 seconds and 
    then double click and open the file }}}

.. R17

Yes! the new file ``sine.eps`` is here.

.. L18

{{{ switch to next slide, exercise 2 }}}

.. R18

Pause the video here, try out the following exercise and resume the video.

Save the sine plot in PDF, PS and SVG formats.

.. L19

{{{ Switch to summary slide }}}

.. R19

This brings us to the end of this tutorial.In this tutorial,we have learnt to,

 1. Save plots using the ``savefig()`` function.
 #. Save the plots in different formats like
    - pdf
    - ps
    - png
    - svg
    - eps

.. R20

Here are some self assessment questions for you to solve

1. Which command is used to save a plot.

   - saveplot()
   - savefig()
   - savefigure()
   - saveplt()

 
2. ``savefig('sine.png')`` saves the plot in,

   - The root directory ``/`` (on GNU/Linux, Unix based systems),
     ``c:\`` (on windows).
   - Will result in an error as full path is not supplied.
   - The current working directory.
   - Predefined directory like ``/documents``.

.. L20

{{Show self assessment questions slide}}

.. L21

{{{solution of self assessment questions on slide}}}

.. R21

And the answers,

1. To save a plot,we use the ``savefig()`` function.

2. Whenever we save a file,it gets saved in the current working directory.

.. L22

{{{ a thank you slide }}}

.. R22

Hope you have enjoyed and found it useful.
Thank you!