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>>>>> "Leon" == Leon Brits <leo...@ne...> writes:

    Leon> Does this help?  Should I tell the axes to "not remember"
    Leon> the out-of-view data?

Yes, this appears to be your problem.  Normally, I would adivse you to
update the data of your bar elements (patches.Rectangle instances).
This would avoid the overhead of creating all the extra objects.  But
for stacked bar graphs this may be more hassle than it's worth.

But you definitely do need to clear the old instances before adding
the new ones.  There are two ways to do this

  ax.cla()  # clear all the axes elements

This might introduce flicker in to your graph so you'll have to test
it.  A hack is to simply clear all the patch instances from the axes.
If you are not using other patch building plot commands (eg hist,
scatter, bar) this should work fine and be the fastest solution

  ax._patches = []

It might be worthwhile to add a more limited clear function to the
axes.  cla clears everything, but in some cases (like this one) you
might just want clear the lines, or the patches, or the text.

If you are following matplotlib-users, I just did some profiling of
animated graphs and found that text operations were eating up about
50% of the CPU time on animated graphs.  The good news is that the
vast majority of this time can be reclaimed with some fairly easy
optimizations.

JDH

On Tue, 25 May 2004 08:38:40 -0500, John Hunter  
<jdh...@ac...> wrote:

>>>>>> "Leon" == Leon Brits <leo...@ne...> writes:
>
>     Leon> Hi, I experience a slowdown in the command canvas.draw().  I
>     Leon> am drawing a moving bargraph by shifting the x-axis and
>     Leon> adding a new bar.  The new bargraph is added every second,
>     Leon> but starts to slows down after 5 minutes.
>
>     Leon> I monitored the time it takes to execute the canvas.draw()
>     Leon> command and this increases from 200ms to over 1 second
>     Leon> within the 5 minutes and therfore the delay since I am
>     Leon> trying to display the new bar every second.
>
>     Leon> Any help appreciated!  Thnaks Leon
>
> Could you post your code, or at least the core of it that does the
> drawing update?
>
> JDH

I cannot give you everything, but here is the main part....


	g_canvas = get_current_fig_manager().canvas

	< SNIP >

	# Build stacked bargraph
	for jin range(data[....])
		# Select axes to add BAR too...
		axes(g_display[j]['axes']['handle'])
	      b = bar(delta_time, h, 1, g_display[j]['offset'], color)
       	g_display[j]['offset'] += h		# build stacked bar
		# setup legend names & colors
             g_display[j]['bars'].append(b)
             g_display[j]['legend'].append(data['legend'])

	< SNIP >

	# Select axes to update...
	axes(g_display[j]['axes']['handle'])
       g_display[j]['maxy'] = Search_YMax(g_display[j]['maxy'],  
g_display[j]['offset'])
       g_display[j]['y-scale'] = Scale_YMax(g_display[j]['maxy'][0])
       g_display[j]['axes']['handle'].set_ylim([0, g_display[j]['y-scale']])
       g_display[j]['axes']['handle'].set_xlim([x_start, x_end])
       legend(g_display[j]['bars'], g_display[j]['legend'], 'lower left')
       ylabel(g_display[j]['unit'], g_font['unit'])
       g_canvas.draw()


Does this help?
Should I tell the axes to "not remember" the out-of-view data?

Thanks for your quick reply!
Cheers
Leon
-- 
==============================
Leon J. Brits
Netronome Systems (Pty) Ltd.
Tel:+27(0)12-6673650
Fax:+27(0)12-6673635

>>>>> "Leon" == Leon Brits <leo...@ne...> writes:

    Leon> Hi, I experience a slowdown in the command canvas.draw().  I
    Leon> am drawing a moving bargraph by shifting the x-axis and
    Leon> adding a new bar.  The new bargraph is added every second,
    Leon> but starts to slows down after 5 minutes.

    Leon> I monitored the time it takes to execute the canvas.draw()
    Leon> command and this increases from 200ms to over 1 second
    Leon> within the 5 minutes and therfore the delay since I am
    Leon> trying to display the new bar every second.

    Leon> Any help appreciated!  Thnaks Leon

Could you post your code, or at least the core of it that does the
drawing update?

JDH

Hi,

I experience a slowdown in the command canvas.draw().
I am drawing a moving bargraph by shifting the x-axis and adding a new bar.
The new bargraph is added every second, but starts to slows down after 5  
minutes.

I monitored the time it takes to execute the canvas.draw() command and  
this increases from 200ms to over 1 second within the 5 minutes and  
therfore the delay since I am trying to display the new bar every second.

Any help appreciated!
Thnaks
Leon

# Using GTK
tyd = time.time()
g_canvas.draw()
print "canvas time =",time.time()-tyd

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