Re: [Matplotlib-users] Create plots in functions, plot later

[Roman B. <be...@sm...>]

Hello,

i made some progress which this issue, but it does still not work
completely:

* Roman Bertle <be...@sm...> [061117 11:04]:
> Hello,
> 
> i try to write a module which evaluates various Data, and occasionally
> creates a plot, which is returned to the user. At the discretion of the
> user, he should be able to show selected plots. This is an example
> module with two approaches for this problem:
> 
> -----------------
> import pylab
> import matplotlib
> 
> def makeplot1():
>     pylab.ioff()
>     fig = pylab.figure()
>     spl1 = fig.add_subplot(211)
>     spl2 = fig.add_subplot(212)
>     spl1.plot([1,4,9,16])
>     spl2.plot([1,3,5,7])
>     pylab.ion()
>     return fig
> 
> def makeplot2():
>     fig = matplotlib.figure.Figure()
>     spl1 = fig.add_subplot(211)
>     spl2 = fig.add_subplot(212)
>     spl1.plot([1,4,9,16])
>     spl2.plot([1,3,5,7])
>     return fig
> ----------------------
> 
> The user fires up ipython and imports my module:
> ipython -pylab
> >>> import plotgen
> 
> After analysizing various data, he wants to look at a particular plot:
> >>> fig = plotgen.makeplot1()
> 
> Now can one make pop up this plot? I tried to make this figure current:
> >>> figure(fig.number)
> but nothing to see. Then:
> >>> draw()
> >>> ion()
> Only show() works, but this pops up all figures defined, and this can be
> a large number of figures if makeplot1() has been called often, or I
> have many figures. I only want to see this particular figure.
> 
> So next try with the object oriented interface:
> >>> fig = plotgen.makeplot2()
> >>> figure(fig.number)
> AttributeError: Figure instance has no attribute 'number'
> 
> Ok, this does not work. In a cookbook i saw that one needs something
> like "canvas = FigureCanvasAgg(fig)". But i cannot use it: As writer of
> module "plotgen" i dont know what backend (Agg) is used by the user. And
> the user simply uses "ipython -pylab" and should not care about the
> backend.

Here i made some progress. One needs a "FigureManager", and in
"ipython -pylab" there is a function "get_current_fig_manager()"; so
here comes my next try:

ipython -pylab
>>> import plotgen
>>> fig = plotgen.makeplot1()
>>> canvas = get_current_fig_manager().canvas
>>> canvas.figure = fig
>>> canvas.print_figure('test')

And the figure is saved into file 'test.png'! The problem is, after
"canvas = get_current_fig_manager().canvas" a plot window appears, but
it is not updated when the figure is changed. I tried methods "show",
"show_all" and "show_now", but nothing is drawn. How can i see the
figure?

Regards, Roman