Efficient animations w/ 2D plots (imshow)

Community matplotlib-users
1

Hello All,
I’m looking for the most efficient way to perform 2D plot animations.

I’ve been experimenting with the animation examples from the Matplotlib cookbook. More specifically I’m using a version of “Animating selected plot elements” that has been modified to work with wxWidgets. I want to do the same type of thing but with 2D plots (
i.e. imshow).

When I try ax.draw_artist(im) where “im” is the AxesImage returned from the initial call to imshow I get an AssertionError for self._cachedRenderer is not None.

What am I doing wrong?

Thanks
Greg

Here is my hacked up version of the example.

The number of blits() to make before exiting

NBLITS = 1000

import matplotlib
matplotlib.use(‘WXAgg’)
matplotlib.rcParams[‘toolbar’] = None

import wx
import sys
import pylab as p
import matplotlib.numerix as nx
import time

allow the user to disable the WXAgg accelerator from the command line

if ‘–no-accel’ in sys.argv:
import matplotlib.backends.backend_wxagg
matplotlib.backends.backend_wxagg._use_accelerator(False)

ax = p.subplot(111)
canvas = ax.figure.canvas

p.subplots_adjust
(left=0.3, bottom=0.3) # check for flipy bugs
p.grid() # to ensure proper background restore

create the initial line

appx = 10.0
appy = 3.8
delta = 0.125
x = p.arange(-appx/2.0, appx/2.0, delta)
y = p.arange(-appy/2.0, appy/2.0, delta)
X, Y = p.meshgrid(x, y)

bivariate_normal(X, Y,sigmax,sigmay,mux,muy)

Z = p.bivariate_normal(X, Y, 0.9, 0.7, 4.1, -0.15)

im = p.imshow(Z,cmap=p.cm.hot)

for profiling

tstart = time.time()
blit_time = 0.0

def update_line(*args):
global blit_time

if update_line.background is None:
    update_line.background = canvas.copy_from_bbox(ax.bbox

)

# restore the clean slate background
canvas.restore_region(update_line.background)
# update the data
im.set_data(p.bivariate_normal(X,Y,
                               0.9,0.7,
                               4.1+p.sin(update_line.cnt/20.0),
                               -0.15+p.cos(update_line.cnt/10.0)))
# just draw the animated artist
ax.draw_artist(im)
# just redraw the axes rectangle

t = time.time()
canvas.blit(ax.bbox)
blit_time += time.time() - t

if update_line.cnt == NBLITS:
    # print the timing info and quit
    frame_time = time.time() - tstart

    print '%d frames: %.2f seconds' % (NBLITS, frame_time)
    print '%d blits:  %.2f seconds' % (NBLITS, blit_time)
    print
    print 'FPS: %.2f' % (NBLITS/frame_time)

    if blit_time > 0:
        print 'BPS: %.2f' % (NBLITS/blit_time)
    global timer
    timer.Stop()

update_line.cnt += 1

update_line.cnt = 0
update_line.background = None

TIMER_ID=100
panel = wx.GetApp()
global timer
timer = wx.Timer(panel,TIMER_ID)
timer.Start(10)
wx.EVT_TIMER(panel,TIMER_ID, update_line)
update_line()
p.show()

···

–
Linux. Because rebooting is for adding hardware.

2

Nevermind. I’m an idiot. I removed the call to update_line() before p.show() and now it works. That was cruft left over from earlier experiments
Cheers,
Greg

···

On 7/24/07, Greg Willden <gregwillden@…287…> wrote:

Hello All,
I’m looking for the most efficient way to perform 2D plot animations.

I’ve been experimenting with the animation examples from the Matplotlib cookbook. More specifically I’m using a version of “Animating selected plot elements” that has been modified to work with wxWidgets. I want to do the same type of thing but with 2D plots (
i.e. imshow).

When I try ax.draw_artist(im) where “im” is the AxesImage returned from the initial call to imshow I get an AssertionError for self._cachedRenderer is not None.

What am I doing wrong?

Thanks
Greg

Here is my hacked up version of the example.

The number of blits() to make before exiting

NBLITS = 1000

import matplotlib
matplotlib.use(‘WXAgg’)

matplotlib.rcParams[‘toolbar’] = None

import wx
import sys
import pylab as p
import matplotlib.numerix as nx
import time

allow the user to disable the WXAgg accelerator from the command line

if ‘–no-accel’ in sys.argv:
import matplotlib.backends.backend_wxagg
matplotlib.backends.backend_wxagg._use_accelerator(False)

ax = p.subplot(111)
canvas = ax.figure.canvas

p.subplots_adjust
(left=0.3, bottom=0.3) # check for flipy bugs
p.grid() # to ensure proper background restore

create the initial line

appx = 10.0
appy = 3.8
delta = 0.125
x = p.arange(-appx/2.0, appx/2.0, delta)

y = p.arange(-appy/2.0, appy/2.0, delta)
X, Y = p.meshgrid(x, y)

bivariate_normal(X, Y,sigmax,sigmay,mux,muy)

Z = p.bivariate_normal(X, Y, 0.9, 0.7, 4.1, -0.15)

im = p.imshow(Z,cmap=p.cm.hot)

for profiling

tstart = time.time()
blit_time = 0.0

def update_line(*args):
global blit_time

if update_line.background is None:

    update_line.background = canvas.copy_from_bbox(ax.bbox

)

# restore the clean slate background
canvas.restore_region(update_line.background)
# update the data
im.set_data(p.bivariate_normal(X,Y,
                               0.9,0.7,


                               4.1+p.sin(update_line.cnt/20.0),
                               -0.15+p.cos(update_line.cnt/10.0)))
# just draw the animated artist
ax.draw_artist(im)
# just redraw the axes rectangle


t = time.time()
canvas.blit(ax.bbox)
blit_time += time.time() - t

if update_line.cnt == NBLITS:
    # print the timing info and quit
    frame_time = time.time() - tstart

    print '%d frames: %.2f seconds' % (NBLITS, frame_time)
    print '%d blits:  %.2f seconds' % (NBLITS, blit_time)
    print
    print 'FPS: %.2f' % (NBLITS/frame_time)

    if blit_time > 0:
        print 'BPS: %.2f' % (NBLITS/blit_time)
    global timer
    timer.Stop()

update_line.cnt += 1

update_line.cnt = 0
update_line.background = None

TIMER_ID=100
panel = wx.GetApp()
global timer
timer = wx.Timer(panel,TIMER_ID)
timer.Start(10)
wx.EVT_TIMER(panel,TIMER_ID, update_line)
update_line()
p.show()

–
Linux. Because rebooting is for adding hardware.

–
Linux. Because rebooting is for adding hardware.