diff -r e675f9208b91 -r 4054b1a6392d savefig/script.rst --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/savefig/script.rst Wed Oct 13 17:32:59 2010 +0530 @@ -0,0 +1,151 @@ +.. Objectives +.. ---------- + +.. At the end of this tutorial, you will be able to + +.. 1. Saving plots using ``savefig()`` function. +.. #. Saving plots in different formats. + + +.. Prerequisites +.. ------------- + +.. 1. should have ``ipython`` and ``pylab`` installed. +.. #. getting started with ``ipython``. +.. #. using plot command interactively. + +.. Author : Anoop Jacob Thomas + Internal Reviewer : + External Reviewer : + Checklist OK? : [2010-10-05] + + +======= +Savefig +======= + +{{{ Show the first slide }}} + +Hello and welcome to the tutorial saving plots. + +{{{ switch to next slide, outline slide }}} + +In this tutorial you will learn how to save plots using Python. And +saving in different formats, and locating the file in the file system. + +{{{ switch to next slide, a sine wave}}} + +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 to next slide, savefig() }}} + +{{{ 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 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 }}} + +{{{ switch to next slide, More on savefig() }}} + +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]] + +{{{ switch to next slide, exercise 1 }}} + +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. Pause here and try to figure it out yourself. + +{{{ Switch focus to the already open plot window }}} + +We still have the sine plot with us, and now let us save the plot as +``sine.eps``. + +{{{ switch to next slide, solution 1 }}} + +{{{ 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. + +{{{ switch to next slide, exercise 2 }}} + +Now you may try saving the same in pdf, ps, svg formats. + +{{{ Switch to summary slide }}} + +This brings us to the end of this tutorial, in this tutorial we +learned to save plots using the function ``savefig()``. Saving the +plots in different formats and locating the files in the file system. + +{{{ switch to Thank you slide }}} + +Thank you!