Re: [Matplotlib-users] making multi panel figures

[Michael R. <raw...@ya...>]

On 01/12/12 Ben Root wrote: 

On Thu, Jan 12, 2012 at 2:20 PM, Michael Rawlins <raw...@ya...> wrote:


>On 01/12/12 Ben Root wrote: 
>
>Just a quick suggestion for cleaning up your code, please look into the 
argparse module to make command-line parsing so much easier to use.
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>http://docs.python.org/dev/library/argparse.html
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>Ben Root
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>Command line parsing?  I'm new to python and matplotlib and was given this code by a colleague. I've managed to make simple modifications. Don't know enough yet to use the examples in the link you provide. 
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>I've simplified my code as much as possible.  The first 50 lines make a map. The code below that makes a 4 panel graphic.  Seems that plt.figure invokes a new plot window. But plt.semilogy, plt.loglog, and plt.hist do not, keeping the panels in a single window. This is what I need. Trying now to figure out how to transfer the fig=plt.figure line into the subplot section, without popping up a new window.
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>Mike
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Ok, a quick crash course:

A "figure" can hold one or more "axes" (or subplots).  When using "plt", you can choose to make figures explicitly with the "fig = plt.figure()" command or not.  The same is true for axes objects.  If you call a command that needs a figure and/or an axes object to have been made and they don't exist, then they are made for you automatically. Otherwise, the most recently accessed figure/axes are assumed.  This is why plt.hist(), plt.semilog() and others are not creating a new figure window if one already existed.

Anyway, for your code, you do not want to bring in the plt.figure() call into the subploting section.  The example you were given takes advantage of pyplot's implicit syntax (where it is implicitly assumed which axes/figure object you are using). However, I personally do not like that approach, and instead decided to show you an explicit style.  I created a foobar() function that takes a blank figure object and other parameters, creates the four subplot axes and performs drawing on each of them.  Note that the title is for the subplot, not for the figure.  If you want a title for the figure above all the other subplots, use "fig.suptitle()".  I then have a loop where a figure is created each time, the foobar() function acts on that figure, saved and then cleared before the next iteration.

Note, I noticed you had "plt.show()" commented out before the call to "plt.savefig()".  Usually, you will want savefig() to come *before* show() because closing the figure window will destroy the figure object, resulting in a blank figure to save if done afterwards.

I hope this is helpful!
Ben Root




OK starting to make sense. Yes very helpful.  I think what's you've set up might work, provided I can pass a filename for data into the function.

At the moment I'm getting an error:

NameError: name 'foobar' is not defined

for the line with:  foobar(fig, m, title)

Mike