"regrid" drops dataset attributes

[brews]

Anytime we call dodola.core.xesmf_regrid, the output data is missing attributes from the input data. It would be great if we could keep — or merge — attrs from input data.

[brews]

Using something like xr.set_options(keep_attrs=True) might get the behavior we need from xesmf. I'm not sure though. I'm not up to date on attrs behavior in xarray.

[dgergel]

It looks like what we need is keep_attrs=True in the call to the xesmf regridder. The default is false for some reason.

e.g.

dodola/dodola/core.py

Line 381 in 0683271

return regridder(x).astype(astype)

would be

if astype:
        return regridder(x, keep_attrs=True).astype(astype)
    return regridder(x)

[brews]

@dgergel I think that's for the old xesmf from a few years back and not the pangeo-supported fork...?

Edit: My rough fix for getting attrs merged from ds to out_ds has been

out_ds.attrs |= ds.attrs
for k, v in ds.variables.items():
    if k in out_ds:
        out_ds[k].attrs |= v.attrs

[dgergel]

@brews I took a look at the source code for the pangeo-supported fork of xesmf and it still has that keep_attrs=True option in applying the regridder (and the default is false), see here: https://github.com/pangeo-data/xESMF/blob/fa07fa6a7d382c8298261170e4e9df894d8f7cb6/xesmf/frontend.py#L382

[brews]

@dgergel Huh! You're right! I'll see if that arg does the trick. Thanks.

[dgergel]

@brews we fixed this, correct? So we can go ahead and close?

[brews]

@dgergel good question. It's a bit of a stale issue but I say we should keep this open. Right now we have a hackish workaround. It works but I'd like to try the solution you recommend before we close this.

[dgergel]

Got it - let's keep it open for now then.