[Matplotlib-users] Colormap norm (vmin, vmax) based on visible part of figure

[David H. <dav...@gm...>]

Hi all,

I'm wondering if anyone knows how to compute colorbar limits (vmin, vmax)
based only on the visible portion of the figure. My use-case is a
pcolormesh(x, y, z) drawn over a Basemap instance. The coordinates x and y
cover the entire globe, but I'm only mapping the Arctic. What happens is
that the normalization is done over the entire z array, while only a subset
of z actually appears on the map.  The colors appearing on the map thus
cover only a small fraction of the entire color range.

>From what I managed to understand, pcolormesh creates a collections of
patches colorcoded based on the array attribute. So my question is if there
is a builtin way to know which items of this collections are clipped so I
can mask this part of the array ?

Thanks a lot,

David