Re: [matplotlib-devel] savefig problem in interactive mode

[Fernando P. <Fer...@co...>]

John Hunter wrote:
>>>>>>"Fernando" == Fernando Perez <Fer...@co...> writes:
> 
> 
>     Fernando> Hi all, I have a question: in interactive (ipython
>     Fernando> -pylab) mode, a call to savefig('foo.eps') (either via
>     Fernando> %run or straight at the prompt) still pops up a GUI plot
>     Fernando> window.  If I run the same script from a system command
>     Fernando> line, the eps is made, but no GUI opens (what I consider
>     Fernando> the correct behavior).
> 
>     Fernando> Is this something that should be fixed in ipython or in
>     Fernando> matplotlib?
> 
> For the sake of clarity, let's consider the canonical script
> 
>     import matplotlib
>     matplotlib.use('PS')
>     from pylab import *
>     plot([1,2,3])
>     savefig('test.ps')
>     show()
> 
> When run from the shell, it does what you want -- makes a PS with no
> popup.  It fails in  ipython (pops up a window) because you have
> already selected a backend and all pylab commands are directed to that
> backend.
> 
> How to fix it?
> 
>  * ipython invokes an external python process to run each script.  Of
>    course you pay a performance hit here, and this would likely change
>    the meaning of the way run is meant to work (eg, are local ipython
>    shell vars available in a "run" script.

Not good.  If users want this, they can always just call !python foo.py and be 
done.  The whole point of %run is to benefit from enhanced tracebacks, debug 
hooks, variable access, etc.  Doing that across processes is basically impossible.

>  * provide better support for backend switching in matplotlib.  Eg,
>    allowing you at any time to call matplotlib.use.  Currently, this
>    only works before the import of pylab.  It may be possible to write
>    a pylab.use that simply rebinds the 4 backend functions:
>    new_figure_manager, error_msg, draw_if_interactive, show.  At the
>    end of a "run", you could simply do a
>    matplotlib.pylab.use(defaultBackend) to rebind.  run could be
>    enhanced to support backend switching
> 
>      run somescript.py -dPS
> 
>    much like one can do from the shell.
> 
>   You know more about python module reloading than I do.  How does one
>   force a module to reload, eg if I wanted to set the rc 'backend'
>   param and then do, eg
> 
>  
>     rcParams['backend'] = 'PS'
>     from backends import new_figure_manager, error_msg, draw_if_interactive, show
> 
> 
>   to get new symbols?

You have to carefully wire reload() calls into the proper backends.  It's 
doable, but doing it generically and with all the complex mpl backend 
machinery would likely take a bit of effort.

> There may be another way, but those two come to mind.  I'll mull it
> over.

It's not a big deal anyway, just something to think about.  My concern is that 
if I run from ipython (for testing/debugging) some big script which is wired 
to dump hundreds of EPS figures to a plots directory (yes, I do stuff like 
that with Gnuplot), my screen is going to be instantly flooded with hundreds 
of windows.


But for now, I'd rather see the tk close bug fixed and the figure() 
improvements I referred to in my other mail ;)

Cheers,

f