matplotlib-users

[Matplotlib-users] Check if figure exists

[Christopher B. <c-...@as...>]

Hi,

If I have a figure:

h = pp.figure(num=14)

What is the best way to check to see if Figure 14 exists? I'm writing a 
function that adds plots to a figure window. I want the function to 
check if the figure exists, and if so, turn off autoscaling (using 
Eric's suggested axes.set_autoscale_on(False)) in case the user has zoomed.

-- 
Christopher Brown, Ph.D.
Department of Speech and Hearing Science
Arizona State University

Re: [Matplotlib-users] Check if figure exists

[Eric F. <ef...@ha...>]

Matthias Michler wrote:
> On Thursday 26 February 2009 20:52:17 Christopher Brown wrote:
>> Hi,
>>
>> If I have a figure:
>>
>> h = pp.figure(num=14)
>>
>> What is the best way to check to see if Figure 14 exists? I'm writing a
>> function that adds plots to a figure window. I want the function to
>> check if the figure exists, and if so, turn off autoscaling (using
>> Eric's suggested axes.set_autoscale_on(False)) in case the user has zoomed.
> 
> Hi Christopher,
> 
> I don't know if my suggestion is the best way, but at least it may be 
> useful ...

I think your suggestion is the only way at present, but it suggests that 
we should provide this capability as part of the API; we don't want to 
force people to access the private _pylab_helpers module directly.

Eric

> 
> regards Matthias
> 
> example code:
> 
> import matplotlib
> import matplotlib.pyplot as plt
> 
> 
> for i in range(5)+[14]:
>     plt.figure(i) # generating some figures
> 
> # get the figure numbers of all existing figures
> fig_numbers = [x.num
>                for x in matplotlib._pylab_helpers.Gcf.get_all_fig_managers()]
> 
> if 14 in fig_numbers:
>     print "figure 14 exists" 
> 
> if plt.figure(14).number in fig_numbers:
>     print "figure 14 exists" 
> 
> 
> 
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Re: [Matplotlib-users] Check if figure exists

[Eric F. <ef...@ha...>]

Christopher Brown wrote:
> Hi,
> 
> If I have a figure:
> 
> h = pp.figure(num=14)
> 
> What is the best way to check to see if Figure 14 exists? I'm writing a 
> function that adds plots to a figure window. I want the function to 
> check if the figure exists, and if so, turn off autoscaling (using 
> Eric's suggested axes.set_autoscale_on(False)) in case the user has zoomed.
> 


I added two functions to pyplot in svn: fignum_exists(num) and 
get_fignums() so that with future releases you won't have to delve into 
_pylab_helpers for this information.

Eric

Re: [Matplotlib-users] Check if figure exists

[João L. S. <js...@fc...>]

Eric Firing wrote:
> I added two functions to pyplot in svn: fignum_exists(num) and 
> get_fignums() so that with future releases you won't have to delve into 
> _pylab_helpers for this information.
> 
> Eric

Wouldn't it be better to have some way to iterate mpl objects, rather 
than having adhoc functions just for figures? I though there was a 
standard way to iterate all figures, all axes etc, something like

import matplotlib as mpl

for fig in mpl.Figures:
     ... do stuff

or something similar. Does something like this exist in mpl?

JLS

Re: [Matplotlib-users] Check if figure exists

[Eric F. <ef...@ha...>]

João Luís Silva wrote:
> Eric Firing wrote:
>> I added two functions to pyplot in svn: fignum_exists(num) and 
>> get_fignums() so that with future releases you won't have to delve into 
>> _pylab_helpers for this information.
>>
>> Eric
> 
> Wouldn't it be better to have some way to iterate mpl objects, rather 
> than having adhoc functions just for figures? I though there was a 
> standard way to iterate all figures, all axes etc, something like
> 
> import matplotlib as mpl
> 
> for fig in mpl.Figures:
>      ... do stuff
> 
> or something similar. Does something like this exist in mpl?

No.  The functions I added to pyplot were to provide more information 
about the figure tracking that pyplot does via the odd Gcf class in 
_pylab_helpers.  This is based on the Matlab practice of having numbered 
figures.

When the pyplot interface is *not* being used  (see 
examples/api/agg_oo.py and examples/user_interfaces/embedding*.py), a 
Figure instance is just that--an instance of a class.  Tracking the 
instances is up to the user, who presumably created them.  The figure is 
at the top of the Artist hierarchy. It *does* track axes that are added 
to it, and you can iterate over those; and those axes track artists that 
are added to them.

Is there a real need for module-level tracking of Figure instances in 
this case where pyplot is not being used?

When pyplot is being used, one can always use pyplot.figure(num) to get 
the Figure object with that number.

Eric