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Savefig

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Hello and welcome to the tutorial saving plots.

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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.

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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.

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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))

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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.

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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.

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

want to save the file.

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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 }}}

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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]]

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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.

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

``sine.eps``.

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

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

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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.

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

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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.

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Thank you!