Re: [Matplotlib-users] how to reverse the colorbar and its label at the same time?

[Paul H. <pmh...@gm...>]

On Sat, Nov 10, 2012 at 7:07 AM, Chao YUE <cha...@gm...> wrote:
>
> Dear all,
>
> Is there a way to reverse the colorbar label, the default is small value at the bottom and big value at the top, yet I would like the big value at the bottom and small value at the top.
>
> all code in pylab mode.
>
> import numpy as np
> import matplotlib as mat
>
> a = np.arange(100).reshape(10,10)
> contourf(a,levels=np.arange(0,101,10))
> colorbar()
>
> in the above figure, colorbar label shows 0 at the bottom and 100 at the top.
> Yet I want the 0 at the top and the 100 at the bottom, with the same sequence of colors in the colorbar.
>
> One way is to reverse the cmap, and then reverse the colorbar labels at the same time:
> a = np.arange(100).reshape(10,10)
> contourf(a,levels=np.arange(0,101,10),cmap=mat.cm.jet_r)
> cbar = colorbar()
> cbar.set_ticks(np.arange(0,101,10))
> cbar.set_ticklabels(np.arange(100,-1,-10))

Chao,

I think it's as simple as:

import numpy as np
import matplotlib.pyplot as plt

a = np.arange(100).reshape(10,10)
fig, ax1 = plt.subplots()
CS = ax1.contourf(a,levels=np.arange(0,101,10))
cbar = plt.colorbar(CS)
cbar.ax.invert_yaxis()

Does that produce the desired results?
-p