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Assign and map a CRS in one step #29
Description
This might be a question out of the scope of the PR, but I'm wondering about the need to raise a warning or something if assign_crs is used without subsequently calling map_crs to avoid getting into logically inconsistent situations. Maybe link map_crs in the assign_crs API docs too?
For example, you can assign_crs without warning or error, but then as soon as you try to access one of the .crs values you hit:
ValueError: found multiple CRS in Dataset or DataArray:
spatial_ref: EPSG:32610
lat: EPSG:4326
Originally posted by @scottyhq in #27 (comment)
Activity
benbovy commentedon Jun 10, 2025
(copied from the same comment thread)
Maybe we could allow something like this:
I.e., both the new CRS and the coordinates to map that CRS are passed together as a 2-length tuple to
.proj.assign_crs(). Note thatpyproj.CRS.from_user_input()may also accept a 2-length tuple in the form(‘epsg’, ‘4322’)but that's probably not a big deal.We could also try to track the CRSes in a Dataset that have been mapped from spatial reference coordinates to other coordinates (or even data variables #21) at the xproj accessor level, but that's tricky to do it right in a lossless way across Xarray operations.