Re: [Matplotlib-users] How can I put a white area in the middle of colorbar showing the masked data?

[Eric F. <ef...@ha...>]

On 2014/03/01 9:57 AM, Chao YUE wrote:
> Dear all,
>
> In many cases in geoscience mapping we want to show the some missing values
> as some special color in the colorbar. like attached one.
>
> I know there is one method in matplotlib colormap called "set_bad", official
> docs says:
>
> Set color to be used for masked values.
>
> But I don't know how to make this work when I call the colorbar method.

It is not a matter of calling the colorbar method, but of setting up the 
colormap used on the color-mapped plot for which the colorbar is made.

The one wrinkle to this is that if you are using contourf, the masked 
regions are not filled at all, so they take on the color of the 
background.  To give them the color you assigned to the colormap with 
set_bad, you need to assign that same color to the background, e.g.

ax.set_axis_bgcolor("#bdb76b")

On re-reading your message, however, I think you are asking something 
else, but it is not clear to me from your example exactly what you are 
trying to do.

The colorbar is strictly for a range or sequence of colors, which can 
include triangle regions for the "over" and "under" values; there is no 
place on the colorbar for a "bad" or "missing" value.  Where would you 
put one?  I don't see any such region on the example colorbar you attached.

Eric



> Is there anyone who have the some successful experience?
>
> Thanks a lot in advance!
>
> Chao
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