How to add colorbar to a histogram?

I have a histogram like this (just like a normal histogram):

In my situation, there are 20 bars always (spanning x axis from 0 to 1) and the color of the bar is defined based on the value on the x axis.

What I want is to add a color spectrum like one of those in http://wiki.scipy.org/Cookbook/Matplotlib/Show_colormaps at the bottom of the histogram but I don't know how to add it.

Any help would be appreciated!

You need to specify the color of the faces from some form of colormap, for example if you want 20 bins and a spectral colormap,

nbins = 20
colors = plt.cm.spectral(np.linspace(nbins))

You can then use this to specify the color of the bars, which is probably easiest to do by getting histogram data first (using numpy) and plotting a bar chart. You can then add the colorbar to a seperate axis at the bottom.

As a minimal example,

import numpy as np
import matplotlib.pyplot as plt
import matplotlib as mpl

nbins = 20
minbin = 0.
maxbin = 1.

data = np.random.normal(size=10000)
bins = np.linspace(minbin, maxbin, nbins)

cmap = plt.cm.spectral
norm = mpl.colors.Normalize(vmin=data.min(), vmax=data.max())
colors = cmap(bins)

hist, bin_edges = np.histogram(data, bins)

fig = plt.figure()
ax = fig.add_axes([0.05, 0.2, 0.9, 0.7])
ax1 = fig.add_axes([0.05, 0.05, 0.9, 0.1])

cb1 = mpl.colorbar.ColorbarBase(ax1, cmap=cmap,
                                norm=norm,
                                orientation='horizontal')

ax.bar(bin_edges[:-1], hist, width=0.051, color=colors, alpha=0.8)
ax.set_xlim((0., 1.))
plt.show()

Which yields,