[Matplotlib-users] collections?

[Daniel H. <dh...@gm...>]

I can't tell if I'm misusing collections here, or if there is a bug.
 Anyway, what I'm trying to do is keep track of a group of rectangles
generated from a bar plot.  Instead of letting there be a large number of
artists added to the axes, I wanted to just group them into a collection
and add the collection instead.  As in the code below:

#!/usr/bin/env python
import numpy
import matplotlib.pyplot as plt
import matplotlib.collections

# just generate some data to plot
x = numpy.linspace(0.0,2.0*numpy.pi,10)
y = numpy.sin(x)

# plot
axes = plt.gca()
bars = plt.bar(x,y,color='red',width=0.1)

# strip out all of the newly inserted rectangles
for b in bars: b.remove()

# and create a collection for plotting the rectangles instead.
coll = matplotlib.collections.PatchCollection(bars)

axes.artists.append(coll)

plt.xlim(0.0,2.0*numpy.pi)
plt.grid(True)
plt.show()

This appears to work at first blush, but if you resize the plot, you can
tell that the rectangles are just fixed in their location now.  I tried
messing around with setting the transform for the new collection object
"coll" in different ways, to no avail.  Any suggestions welcome ;)

-- 
Daniel Hyams
dh...@gm...