Is there a recipe for converting a GMT cpt file for use in matplotlib/cartopy?
Not that I know of, but someone did write some code to do the opposite (matplotlib to gmt) before, you can find it at https://github.com/mjziebarth/gmt-python-extensions/blob/master/gmt_extensions/colormap.py.
Is there a particular colormap you’d like to convert? One of the Scientific Colour Maps perhaps or another one?
Thanks for the link. It’s about a custom-made colour map.
This repository may provide functions you need: