[Matplotlib-users] RE : Re: Problem with pylab.fill

[Pellegrini E. <eri...@ya...>]

Hi John,
   
  thank you very much for the hand.
   
  I think that I have found my mistake. I was launching my script trough "Idle" that seems to be the reason why it was to slow. Running my script with the command line or by double-clicking on it gave results similar to yours. Would you know why Idle application slows down so much the execution of my script ?
   
  By the way, using the Collection class, would you have any idea how to set different colors to the polygons ? Using set_color method change the color of all the plygons.
   
  Thanks again

  Eric
  
John Hunter <jdh...@ac...> a écrit :
  >>>>> "Pellegrini" == Pellegrini Eric writes:

Pellegrini> Hi everybody, I would like to build an application
Pellegrini> where many filled polygons will have to be displayed
Pellegrini> on the screen. To do so, I would like to use
Pellegrini> matplotlib but, up to now, my application is not fast
Pellegrini> enough.

Hmm, I'm not seeing the performance problem on my system -- I can
create and save the figure in a fraction of a second. Is your numerix
setting set to numpy? Run the script with --verbose-helpful and send
us the output.

A few things to note: if you really want regular polygons, eg the
squared in your example, do any of the plot markers work for you.

plot(x, marker='s')

will be about as fast as mpl gets. You can set the marker size with
the markersize property.

Second, if you need arbitrary polygons, and need a lot of them, a
polygon collection will be faster. I had to bump the number of polys
up to about 8000 to show a dramatic performance difference.

Here are two scripts and performance numbers -- one using fill and one
using a polygon collection

> time python test.py -dAgg
6.595u 0.089s 0:06.68 99.8% 0+0k 0+0io 0pf+0w

> time python test2.py -dAgg
0.565u 0.033s 0:00.59 100.0% 0+0k 0+0io 0pf+0w

> cat test.py
import pylab

x = range(0,81000,10)
pylab.axis('off')
for i in range(0,len(x)-1):
pylab.fill([x[i],x[i+1],x[i+1],x[i]],[10,10,20,20])
pylab.axis((0,max(x),0,610))
pylab.savefig('test')
pylab.show()

> cat test2.py
import pylab
from matplotlib.collections import PolyCollection
fig = pylab.figure()
ax = fig.add_subplot(111)
x = range(0,81000,10)

pylab.axis('off')
verts = [((x[i], 10), (x[i+1], 10), (x[i+1], 20), (x[i], 20)) for i in range(len(x)-1)]
col = PolyCollection(verts)
ax.add_collection(col)
pylab.axis((0,max(x),0,610))
pylab.savefig('test')
pylab.show()


 		
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