savefig.rst
changeset 160 f394adb5b00e
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/savefig.rst	Fri Sep 17 18:12:48 2010 +0530
@@ -0,0 +1,111 @@
+=======
+Savefig
+=======
+
+Hello and welcome to the tutorial. In this tutorial you will learn how
+to save plots using Python.
+
+Start your IPython interpreter with the command ::
+
+  ipython -pylab
+
+It will start your IPython interpreter with the required python
+modules for plotting and saving your plots.
+
+{{{ Open ipython }}}
+
+Now let us plot something, 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, ::
+
+  x = linspace(-3*pi,3*pi,100)
+
+We have stored required points in x. Now let us plot the points using
+the statement ::
+
+  plot(x,sin(x))
+
+{{{ Keep the plot open }}}
+
+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.
+
+{{{ Switch the focus to IPython interpreter window }}}
+
+For saving the plot, we will use savefig function, and it has to be
+done with the plot window open. The statement is, ::
+
+  savefig('/home/fossee/sine.png')
+
+Notice that ``savefig`` function takes one argument which is a string
+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.
+
+{{{ Highlight the /home/fossee part using mouse movements }}}
+
+Also, note that we gave the full path or the absolute path to which we
+want to save the file.
+
+{{{ Highlight the .png part using mouse movements }}}
+
+Here I have used an extension ``.png`` which means i want to save the
+image as a PNG file.
+
+Now let us locate ``sine.png`` file saved. We saved the file to
+``/home/fossee`` so let us navigate to ``/home/fossee`` using the
+file browser.
+
+{{{ Open the browser, navigate to /home/fossee and highlight the file
+sine.png }}}
+
+Yes, the file ``sine.png`` is here and let us check the it.
+
+{{{ 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 }}}
+
+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.
+
+#[slide must give the extensions for the files - Anoop]
+
+Let us now try to save the plot in eps format. ``eps`` stands for
+encapsulated post script, and it can be embedded in your latex
+documents.
+
+{{{ Switch focus to the already open plot window }}}
+
+We still have the old sine plot with us, and now let us save the plot
+as ``sine.eps``.
+
+{{{ Switch focus to IPython interpreter }}}
+
+Now, We will save the plot using the function ``savefig`` ::
+
+  savefig('/home/fossee/sine.eps')
+
+{{{ Switch focus to file browser window }}}
+
+Now let us go to ``/home/fossee`` and see the new file created.
+
+{{{ Highlight the file sine.eps with a single mouse click for 2
+seconds and then double click and open the file }}}
+
+Yes! the new file ``sine.eps`` is here.
+
+Now you may try saving the same in pdf, ps, svg formats.
+
+Let us review what we have learned in this session! We have learned to
+save plots in different formats using the function ``savefig()``.
+
+Thank you!
+
+..  Author: Anoop Jacob Thomas <anoop@fossee.in>
+    Reviewer 1:
+    Reviewer 2:
+    External reviewer: