[Matplotlib-users] Re : alternative to imshow with polar axes ?

[Auré G. <aur...@ya...>]

Really  no one to point me in the right direction ?
This is really important, I'm trying to wrap up a publication and this is the 
only element missing...




________________________________
De : Auré Gourrier <aur...@ya...>
À : mat...@li...
Envoyé le : Jeu 10 mars 2011, 15h 40min 04s
Objet : [Matplotlib-users] alternative to imshow with polar axes ?


Dear all,

Once again, I turn for help.
I'm trying to plot a polar image using colormap values for the theta values and 
increasing alpha values along the radius.
I do this using imshow passing the rgba tuple at each pixel position which works 
very nicely with rectangular axes, but fails to display using polar axes (see 
code below). 

As usual, I've done a fair bit of digging to find where the problem is and 
whether I could make out an alternate solution but haven't managed to come 
through. I've tried using pcolormesh but I don't see how to pass the rgba tuple
Can anyone point me in the right direction.
I'm using matplotlib 1.0.1 and Python 2.4

Cheers,

Auré

------
import matplotlib as mpl
from matplotlib import pylab
import numpy as  np

#build custom colormap
cm_sym =customfunc()

#define mesh grid
theta = np.arange(0.,2.*math.pi+2.*math.pi/9,2.*math.pi/9)
r = np.arange(0,1.1,0.1)
X,Y = np.meshgrid(r,theta)

#define rgba array
polarcolorseq = mpl.cm.ScalarMappable(cmap=cm_hsvsym).to_rgba(Y)
#set an increasing alpha value along the radius
polarcolorseq[:,:,-1] = [list(np.arange(0,1.1,.1))]*10

pylab.figure(figsize=(10,5),dpi=100,facecolor='white')

#display using rectangular axis
ax = pylab.subplot((121),axisbg='k')
ax.imshow(np.flipud(np.swapaxes(polarcolorseq,0,1)))

#display using polar axis
ax2 = pylab.subplot((122),axisbg='k',projection='polar')    #also tried with 
polar=True
ax2.imshow(np.flipud(np.swapaxes(polarcolorseq,0,1)))

pylab.draw()