Thread: [Matplotlib-users] creating an object oriented matplotlib figure

I want to create a matplotlib figure as part of a program I am writing 
and therefore would like to create the figure in a fully object oriented 
way, ie not in the pyplot state-full way.  I understand how to work with 
a figure object to create axes objects and then fill the axes objects 
with primitive artists but I can't figure out what type of object to put 
the figure object in to get it displayed.  From digging around in the 
source it looks like the show() method comes from the backend, but when 
I looked in 'matplotlib/backends/backend_agg' I saw no such object.  
What am I missing?  I guess I could put the figure in a Qt window, but I 
like the functionality provided by the default matplotlib window.

Thanks for the help

Hi Kelson,

2013/1/16 Kelson Zawack <kb...@co...>

> I want to create a matplotlib figure as part of a program I am writing
> and therefore would like to create the figure in a fully object oriented
> way, ie not in the pyplot state-full way.  I understand how to work with
> a figure object to create axes objects and then fill the axes objects
> with primitive artists but I can't figure out what type of object to put
> the figure object in to get it displayed.

using qt4agg for me this works (version 1.2.0)
fig = plt.figure()
ax = fig.add_subplot(111)
ax.plot([1,2])
fig.show()

>From digging around in the
> source it looks like the show() method comes from the backend, but when
> I looked in 'matplotlib/backends/backend_agg' I saw no such object.
> What am I missing?  I guess I could put the figure in a Qt window, but I
> like the functionality provided by the default matplotlib window.
>
> Thanks for the help
>

"agg" is not an interactive backend and is useful only when saving figures (
http://matplotlib.1069221.n5.nabble.com/Backend-Agg-show-plot-td13162.html).
Thats why there is no show().
e.g. qt4agg gets show from qt4

does this help?

Francesco


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Ok, I understand about agg, but I am still a bit confused.  First when I 
run the suggested code using whatever the default backend is the figure 
is only displayed for a second and then it goes away and the program 
ends.  I guess what I am really interested in is what plt.figure() 
does.  It seems to be creating a figure manager which has a canvas and a 
figure in it, but which one of these is responsible for the 
showing/saving to file?

Thanks for your help


On 1/16/13 5:02 AM, Francesco Montesano wrote:
> Hi Kelson,
>
> 2013/1/16 Kelson Zawack <kb...@co... <mailto:kb...@co...>>
>
>     I want to create a matplotlib figure as part of a program I am writing
>     and therefore would like to create the figure in a fully object
>     oriented
>     way, ie not in the pyplot state-full way.  I understand how to
>     work with
>     a figure object to create axes objects and then fill the axes objects
>     with primitive artists but I can't figure out what type of object
>     to put
>     the figure object in to get it displayed. 
>
> using qt4agg for me this works (version 1.2.0)
> fig = plt.figure()
> ax = fig.add_subplot(111)
> ax.plot([1,2])
> fig.show()
>
>     From digging around in the
>     source it looks like the show() method comes from the backend, but
>     when
>     I looked in 'matplotlib/backends/backend_agg' I saw no such object.
>     What am I missing?  I guess I could put the figure in a Qt window,
>     but I
>     like the functionality provided by the default matplotlib window.
>
>     Thanks for the help
>
>
> "agg" is not an interactive backend and is useful only when saving 
> figures 
> (http://matplotlib.1069221.n5.nabble.com/Backend-Agg-show-plot-td13162.html). 
> Thats why there is no show().
> e.g. qt4agg gets show from qt4
>
> does this help?
>
> Francesco
>
>
>
>     ------------------------------------------------------------------------------
>     Master Java SE, Java EE, Eclipse, Spring, Hibernate, JavaScript,
>     jQuery
>     and much more. Keep your Java skills current with LearnJavaNow -
>     200+ hours of step-by-step video tutorials by Java experts.
>     SALE $49.99 this month only -- learn more at:
>     http://p.sf.net/sfu/learnmore_122612
>     _______________________________________________
>     Matplotlib-users mailing list
>     Mat...@li...
>     <mailto:Mat...@li...>
>     https://lists.sourceforge.net/lists/listinfo/matplotlib-users
>
>

2013/1/16 Kelson Zawack <kb...@co...>:
> I want to create a matplotlib figure as part of a program I am writing
> and therefore would like to create the figure in a fully object oriented
> way, ie not in the pyplot state-full way.  I understand how to work with
> a figure object to create axes objects and then fill the axes objects
> with primitive artists but I can't figure out what type of object to put
> the figure object in to get it displayed.  From digging around in the
> source it looks like the show() method comes from the backend, but when
> I looked in 'matplotlib/backends/backend_agg' I saw no such object.
> What am I missing?  I guess I could put the figure in a Qt window, but I
> like the functionality provided by the default matplotlib window.
>
> Thanks for the help
>

Hi,
if you need an embedded figure in some gui app (supported with
matplotlib backends),
you may check some demos on this topic:
http://matplotlib.org/examples/user_interfaces/index.html
embedding_in_ ... (gtk, tk, qt, wx)
You can also reuse the gui elements such as toolbar etc.
I have no experience with qt, but apparently, there is an example for this:
http://matplotlib.org/examples/user_interfaces/embedding_in_qt4_wtoolbar.html
Or is it some more specific problem, you are encountering?

hth,
   vbr

On 1/16/2013 4:39 AM, Kelson Zawack wrote:
> I want to create a matplotlib figure as part of a program I am writing
> and therefore would like to create the figure in a fully object oriented
> way, ie not in the pyplot state-full way.


Perhaps you will find it useful to look at the TSPlot class at
http://econpy.googlecode.com/svn-history/r175/trunk/abm/gridworld/gridworld.py

Alan Isaac

On Wed, Jan 16, 2013 at 5:50 AM, Kelson Zawack <kb...@co...> wrote:

>  Ok, I understand about agg, but I am still a bit confused.  First when I
> run the suggested code using whatever the default backend is the figure is
> only displayed for a second and then it goes away and the program ends.  I
> guess what I am really interested in is what plt.figure() does.  It seems
> to be creating a figure manager which has a canvas and a figure in it, but
> which one of these is responsible for the showing/saving to file?
>
> Thanks for your help
>
>
If the plot only appears for a moment, then that would be a bug.  Could you
double-check which version of matplotlib you are running?

Ben Root

I am running 1.2.0
On 1/16/13 10:23 AM, Benjamin Root wrote:
>
>
> On Wed, Jan 16, 2013 at 5:50 AM, Kelson Zawack <kb...@co... 
> <mailto:kb...@co...>> wrote:
>
>     Ok, I understand about agg, but I am still a bit confused.  First
>     when I run the suggested code using whatever the default backend
>     is the figure is only displayed for a second and then it goes away
>     and the program ends.  I guess what I am really interested in is
>     what plt.figure() does.  It seems to be creating a figure manager
>     which has a canvas and a figure in it, but which one of these is
>     responsible for the showing/saving to file?
>
>     Thanks for your help
>
>
> If the plot only appears for a moment, then that would be a bug.  
> Could you double-check which version of matplotlib you are running?
>
> Ben Root

So I looked into it and the reason calling the show method for a 
Figure/FigureManager causes the figure to be visible only for an instant 
is that, at least in the case for tkagg, there is no call to a function 
that blocks until the figure window is closed and as a result the figure 
is displayed then the call to show ends, the figure closes, and the 
program moves on.  This is in contrast to the behavior of the callable 
object invoked by pyplot.show() which calls a mainloop method to block.  
Since I am not super familiar with the internals of Matplotlib I am not 
sure the best way to fix this, but one option, in the case of tkagg, is 
to add a call to tk.mainloop() to the end of FigureManagerTkAgg.show() 
as is done in tkagg's Show object.

Just my 2 cents


On 1/16/13 10:23 AM, Benjamin Root wrote:
>
>
> On Wed, Jan 16, 2013 at 5:50 AM, Kelson Zawack <kb...@co... 
> <mailto:kb...@co...>> wrote:
>
>     Ok, I understand about agg, but I am still a bit confused.  First
>     when I run the suggested code using whatever the default backend
>     is the figure is only displayed for a second and then it goes away
>     and the program ends.  I guess what I am really interested in is
>     what plt.figure() does.  It seems to be creating a figure manager
>     which has a canvas and a figure in it, but which one of these is
>     responsible for the showing/saving to file?
>
>     Thanks for your help
>
>
> If the plot only appears for a moment, then that would be a bug.  
> Could you double-check which version of matplotlib you are running?
>
> Ben Root