[matplotlib-devel] colorbar extension size

[Andrew D. <aj...@gm...>]

I would like some feedback on a new feature I have developed to control the
length of colorbar extension triangles. This is a feature I have desired
for some time, so that the plots I produce with matplotlib can be more
consistent with those produced from other popular plotting software (e.g.,
IDL). I have added a new keyword argument, extendfrac, to the ColorbarBase
class. This may be set to a scalar, a two-tuple, the string 'auto', or  the
string 'default'. The behaviour of this keyword depends on the setting of
the existing spacing keyword argument.

For spacing='uniform' or spacing='proportional':
    extendfrac=None - sets the lengths of both the minimum and maximum
colorbar extension triangles to 0.05 times the interior colorbar length
(the existing hard-coded setting).
    extendfrac='default' - same as None.
    extendfrac=FRACTION - sets the lengths of both the minimum and maximum
colorbar extension triangles to the given fraction of the interior colorbar
length.

For spacing='uniform':
    extendfrac='auto' - sets the lengths of both the minimum and maximum
colorbar extension triangles to be the same as the length of the interior
boxes.

For spacing='proportional':
    extendfrac='auto' - sets the length of the minimum colorbar extension
triangle to the length of the left/bottom-most interior box, and the length
of the maximum colorbar extension triangle to the length of the
right/top-most interior box.
    extendfrac=(FRACTION1, FRACTION2) - as for FRACTION above but the
minimum and maximum extension triangles may be different lengths.

This is quite a small modification actually, but it does change the API for
colorbars. I am wondering if this could be included in matplotlib? I have
set up a fork of matplotlib on Github to implement this feature, if anyone
thinks it is worth it...

Andrew