drop all but specified data_variables/coordinates as a convenience function

[jbusecke]

I often work with datasets that consist out of a lot of data_variables and coordinates.
Often I am only concerned about a subset of variables, and for convenience drop all but a selected list of variables with a little snippet like this:

Code Sample, a copy-pastable example if possible

def xr_keep(obj, varlist):
    """drop all data_vars exept the ones provided in `varlist` """
    obj = obj.copy()
    drop_vars = [a for a in obj.data_vars if a not in varlist]
    return obj.drop(drop_vars)

I would love to have this functionality available as a DataArray/Dataset function. It could look something like da_slim = da.drop_all_but(['var1, 'var3']). Would this be of interest to people here? Then I could try to put in a PR.

[spencerkclark]

Something that is currently possible, though perhaps not super well-documented, is ds.get(['var1', 'var3']). This will select only 'var1' and 'var3' from the Dataset and omit any others.

[dcherian]

ds[['var1', 'var3']] also works AFAIR.

@jbusecke Can you send in a PR to update the docs? https://xarray.pydata.org/en/stable/data-structures.html#dataset

[dcherian]

I often work with datasets that consist out of a lot of data_variables and coordinates.

I'm pretty sure there's an issue request somewhere to add keep_vars to the open_*dataset functions if you wanted to tackle that too :)

[jbusecke]

Wow. Thats awesome. Had no clue about it. I will put in a PR for the docs for sure. Might take a bit though.
Ill also take a look at the keep_vars option.

[jbusecke]

Ok I have submitted a PR for the xarray.Dataset.get function.

@dcherian, I was not able to find that issue you mentioned. I would certainly be interested to have a look in the future.