Hi folks,
I have encountered a problem using colorbar and set_under with a color
map that has only 32 colors. The downward arrow is not filled with the
correct color. If 64 colors are used, the arrow is filled correctly. I
actually want 8 colors.
The test code is essentially image_masked.py from the 0.90.0 examples.
if I use: palette = cm.get_cmap("gray", 64)
the plot is OK.
if I use: palette = cm.get_cmap("gray", 32)
it is not OK.
In both cases, the upper arrow is the correct color.
I am using matplotlib version 0.90.0.
Here is the complete code:
#!/usr/bin/env python
'''imshow with masked array input and out-of-range colors.
'''
from pylab import *
import matplotlib.numerix.ma as ma
import matplotlib.colors as colors
delta = 0.025
x = y = arange(-3.0, 3.0, delta)
X, Y = meshgrid(x, y)
Z1 = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
Z = 10 * (Z2-Z1) # difference of Gaussians
# Set up a colormap:
#palette = cm.gray # OK
palette = cm.get_cmap("gray",32) # Not OK
#palette = cm.get_cmap("gray",64) # OK
palette.set_over('r', 1.0)
palette.set_under('g', 1.0)
palette.set_bad('b', 1.0)
# Alternatively, we could use
# palette.set_bad(alpha = 0.0)
# to make the bad region transparent. This is the default.
# If you comment out all the palette.set* lines, you will see
# all the defaults; under and over will be colored with the
# first and last colors in the palette, respectively.
Zm = ma.masked_where(Z > 1.2, Z)
# By setting vmin and vmax in the norm, we establish the
# range to which the regular palette color scale is applied.
# Anything above that range is colored based on palette.set_over, etc.
im = imshow(Zm, interpolation='bilinear',
cmap=palette,
norm = colors.Normalize(vmin = -1.0, vmax = 1.0, clip = False),
origin='lower', extent=[-3,3,-3,3])
title('Green=low, Red=high, Blue=bad')
# extend choices are "both", "min", "max" and "neither"
colorbar(im, extend='both', shrink=0.8)
show()
--
Ms. Carol A. Leger
SRI International Phone: (650) 859-4114
333 Ravenswood Avenue G-273
Menlo Park, CA 94025 e-mail: [EMAIL PROTECTED]
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