1 =======

     2 Savefig

     3 =======

     4 

     5 Hello and welcome to the tutorial. In this tutorial you will learn how

     6 to save plots using Python.

     7 

     8 Start your IPython interpreter with the command ::

     9 

    10   ipython -pylab

    11 

    12 It will start your IPython interpreter with the required python

    13 modules for plotting and saving your plots.

    14 

    15 {{{ Open ipython }}}

    16 

    17 Now let us plot something, let us plot a sine wave from minus 3 pi to

    18 3 pi. Let us start by calculating the required points for the plot. It

    19 can be done using linspace as, ::

    20 

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

    22 

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

    24 the statement ::

    25 

    26   plot(x,sin(x))

    27 

    28 {{{ Keep the plot open }}}

    29 

    30 Done! we have made a very basic sine plot, now let us see how to save

    31 the plot for future use so that you can embed the plot in your

    32 reports.

    33 

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

    35 

    36 For saving the plot, we will use savefig function, and it has to be

    37 done with the plot window open. The statement is, ::

    38 

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

    40 

    41 Notice that ``savefig`` function takes one argument which is a string

    42 which is the filename. The last 3 characters after the ``.`` in the

    43 filename is the extension or type of the file which determines the

    44 format in which you want to save.

    45 

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

    47 

    48 Also, note that we gave the full path or the absolute path to which we

    49 want to save the file.

    50 

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

    52 

    53 Here I have used an extension ``.png`` which means i want to save the

    54 image as a PNG file.

    55 

    56 Now let us locate ``sine.png`` file saved. We saved the file to

    57 ``/home/fossee`` so let us navigate to ``/home/fossee`` using the

    58 file browser.

    59 

    60 {{{ Open the browser, navigate to /home/fossee and highlight the file

    61 sine.png }}}

    62 

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

    64 

    65 {{{ Open the file sine.png and show it for two-three seconds and then

    66 close it and return to IPython interpreter, make sure the plot window

    67 is still open, also don't close the file browser window }}}

    68 

    69 So in-order to save a plot, we use ``savefig`` function. ``savefig``

    70 can save the plot in many formats, such as pdf - portable document

    71 format, ps - post script, eps - encapsulated post script, svg -

    72 scalable vector graphics, png - portable network graphics which

    73 support transparency etc.

    74 

    75 #[slide must give the extensions for the files - Anoop]

    76 

    77 Let us now try to save the plot in eps format. ``eps`` stands for

    78 encapsulated post script, and it can be embedded in your latex

    79 documents.

    80 

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

    82 

    83 We still have the old sine plot with us, and now let us save the plot

    84 as ``sine.eps``.

    85 

    86 {{{ Switch focus to IPython interpreter }}}

    87 

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

    89 

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

    91 

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

    93 

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

    95 

    96 {{{ Highlight the file sine.eps with a single mouse click for 2

    97 seconds and then double click and open the file }}}

    98 

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

   100 

   101 Now you may try saving the same in pdf, ps, svg formats.

   102 

   103 Let us review what we have learned in this session! We have learned to

   104 save plots in different formats using the function ``savefig()``.

   105 

   106 Thank you!

   107 

   108 ..  Author: Anoop Jacob Thomas <anoop@fossee.in>

   109     Reviewer 1:

   110     Reviewer 2:

   111     External reviewer: