So far I have tried this...
colourmap = cm.get_cmap("Greys_r")
colourmap = colourmap._segmentdata
# exclude 0, 0, 0...i.e. black from dictionary
bvals = colourmap['blue'][1:]
gvals = colourmap['green'][1:]
rvals = colourmap['red'][1:]
colourmap = { "blue":bvals, "green":gvals, "red":rvals }
colourmap = cm.set_cmap(colourmap)
But it doesn't seem to like the set_cmap command
colourmap = cm.set_cmap(colourmap)
AttributeError: 'module' object has no attribute 'set_cmap'
So I guess that isn't the way, nor I suspect is that all that elegant.
Martin
mdekauwe wrote:
>
> Hi,
>
> I am setting a colourbar where I explictly set the tick intervals. However
> I would like to exclude the colour black from this colourbar. The reason
> for this is I would like to overplot some contour lines in black, so would
> like to make them stand out.
>
> An example...where I would like to exclude black as the bottom colour of
> the colourbar, i.e. use the next level of gray.
>
> import numpy as np
> from mpl_toolkits.basemap import Basemap
> import matplotlib.pyplot as plt
> import matplotlib.colors as colors
> import matplotlib as mpl
>
> data = np.random.randint(0,50,100*100).reshape(100, 100)
> m = Basemap(llcrnrlon=1.5, llcrnrlat=10.5, urcrnrlon=3.5, urcrnrlat=13.5,
> resolution='c', projection='cyl')
> fig = plt.figure(figsize=(8, 6))
> ax = fig.add_axes([0.1, 0.1, 0.6, 0.7])
> m.ax = ax
>
> colourmap = plt.cm.Greys_r
> ticks = [0, 10, 20, 30, 40, 50]
> norm = colors.BoundaryNorm(ticks, colourmap.N)
> im = m.imshow(data, colourmap, norm=norm, interpolation='nearest')
> pos = ax.get_position()
> l, b, w, h = pos.bounds
> cax = plt.axes([l+w+0.045, b, 0.05, h])
> cbar = mpl.colorbar.ColorbarBase(cax, cmap=colourmap, norm=norm,
> ticks=ticks)
> plt.show()
>
> Many thanks,
>
> Martin
>
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