Remapping coordinates with a function

[mgunyho]

Hello,

I'm frequently using something like

da = da.assign_coords(x=some_function(da.x))

to reassign the coordinates using a callable. However, usually, I have more descriptive names than da and x, so I end up having to type a lot:

some_array = some_array.assign_coords(dimension_with_a_long_name=some_function(some_array.dimension_with_a_long_name))

I was hoping that there could be a way to remap the coordinates using a function, without having to retype the array and coordinate name, like

some_array = some_array.map_coords(dimension_with_a_long_name=some_function)

I see that it's possible to pass a Callable to assign_coords, but that is computed on the whole array (da in the first example) and not on the coordinate. Have I missed something, is something like this possible with the current API? Or should I raise an issue about this?

[max-sixty]

Thanks for starting a discussion @mgunyho

My initial sense is this may be too specific to add a method for (though people should 👍 if they have the same issue). But I wonder whether we could make this easier using the more general methods — e.g. da.coords = da.coords.map(func)?

[mgunyho]

Yeah, a separate method is probably too much. Another option I thought of could be some dim kwarg to assign_coords, but that might interfere with more complicated use cases.

I just realized that I can do da["dim_name"] = func(da.dim_name), which still requires typing the coordinate name twice, but at least it can be auto-completed.