cm = get_cmap('RdBu')
Ncol = 501
cccol = cm(1.0 * arange(Ncol) / Ncol)
cax = fig.add_axes([0.15, 0.15, 0.05, 0.4])
norm = mpl.colors.Normalize(vmin=valmin, vmax=valmax)
cb1 = mpl.colorbar.ColorbarBase(cax, cmap=cm, norm=norm, orientation='vertical'
    )
draw()
savefig('/tmp/bla.png')
Matplotlib ColorbarBase: delete color separators