The out-of-bounds colors can be set using the set_over and set_under methods of the colormap; see the documentation. You'll need to specify these values when you create your colormap. I don't see any matplotlibrc setting to set the default for this, though. You might also want to ask on the matplotlib mailing list.
Edit: I see what is going on. The white area you describe is not beyond the limits of the color range. It is simply the blank background of the axes. Because you are only plotting certain levels, any levels outside that range will not be plotted at all, leaving those areas blank. To get what you want, do this:
cs = pyplot.contourf(x,y,z,levels=np.arange(50, 220, 20), cmap=pyplot.cm.jet, extend="both")
cb = pyplot.colorbar(cs)
The "extend" argument is the key; it tells contourf to go ahead and plot all contours, but collapse all outside the given range into "too big" and "too small" categories. The cs.set_clim call is necessary to work around an oddity I discovered in contourf while debugging this; for some reason when you use extend, it manipulates the data limits, so we need to reset them back to what we want them to be.
Also, just as a matter of style, you shouldn't be doing things like Colormap.set_under(cmap,color='k'). This is calling the class method and explicitly passing the instance in, which is an odd way to do it. Just do cmap.set_under(color="k").
cs = m.contourf(x,y,data,clevs,cmap=pyplot.cm.Spectral)
cmap=matplotlib.colors.Colormap('Spectral') matplotlib.colors.Colormap.set_under(cmap,color=(0.4667,0,0.5333)) cs = m.contourf(x,y,data,clevs,cmap=cmap)
File "/usr/lib/pymodules/python2.7/matplotlib/contour.py", line 943, in _process_colors self.monochrome = self.cmap.monochrome AttributeError: Colormap instance has no attribute 'monochrome'
You are instantiating the base Colormap class, creating a new, empty Colormap, not using the "spectral" colormap. The easiest way to do what you want is probably to do cmap = pyplot.cm.Spectral and then do cmap.set_under(...). This will modify the Spectral colormap to have the specified under-value. Note that since you are modifying the actual Spectral colormap object, this will remain in effect on all subsequent plots using the Spectral colormap.
That makes sense, but employing this did not change the resulting plot, and the "over/under" color is still white.
It's getting too hard to do this in the abstract. You'll need to provide some example code.
from matplotlib import pyplot as plt from numpy import arange,meshgrid from matplotlib.colors import Colormap x,y = arange(-10,10),arange(-10,10) x,y=meshgrid(x,y) z = x**2+y**2 clevs=arange(50,220,20) cmap=plt.cm.jet Colormap.set_under(cmap,color='k') cs = plt.contourf(x,y,z,clevs,cmap=cmap) plt.colorbar(cs) plt.show()