issue_comments

We should fix set, though for your case it's best to switch to drop_vars

This also happens with other iterables like dict_keys.

drop_vars was just added! Let me know any questions / issues. We should fix set, though for your case it's best to switch to drop_vars

👍 re @keewis 's point re ds[variables]

the reason for set raising an error is that in drop is_list_like(labels) or is_scalar(labels) is used instead of isinstance(labels, str) or not isinstance(labels, Iterable). Since is_list_like explicitly checks for tuple and list, passing set obviously won't call the right method.

~drop_vars has been deprecated.~ Apparently that is wrong. Sorry for adding to the noise.

Ah, thanks very much! I'll switch to using that syntax instead.

explicitly selecting should work like this: python ds = xr.Dataset( {"a": ("b", [0, 1, 2]), "c": ("b", [-1, 2, 4]), "d": ("b", [5, 1, 3])}, coords={"b": list("abc")}, ) variables = ["a", "d"] ds[variables] I think Dataset.__getitem__ allows any kind of sequence here (e.g. sets)

I apologize for this slight tangent but it's related to why we use sets in drop(). Is there a good way in xarray to only keep a list of variables? Our approach is to create a set of all variable and subtract from it a set of variables we want to keep and to drop the resulting set of variables we don't want to keep. But it's hard for me to imagine others don't also need this functionality.

Additionally, I think we have a documentation bug: I can't reach the documentation on drop.

Yes, I noticed that, too. I assumed it wasn't being documented anymore because it was considered deprecated.

so I guess we need to figure out why sets don't work anymore?

I think drop was deprecated in favor of drop_sel and drop_vars (#3475). Using v0.14.1, this works: python ds = xr.Dataset({"a": ("b", [0, 1, 2]), "c": [-1, 2, 4]}, coords={"b": list("abc")}) ds.drop_vars({"a", "b"}) ds.drop_vars(["a", "b"]) ds.drop(["a", "b"])

Additionally, I think we have a documentation bug: I can't reach the documentation on drop.

@dcherian - are you suggesting that @xylar change his downstream code to use drop_vars instead? drop_vars has been deprecated. I don't think that's the right response here.

I'm confused. In 0.14.1, drop_vars seems to have just been introduced and drop seems to have been dropped.

How about drop_vars instead?

Yes, I switched to drop_vars but first I had to make a new build of my conda package that constrains the dependency xarray <0.14.0 because it's broken with 0.14.1. So that's why I'm concerned. I have to do a new release before this fix propagates to my users.

So @rabernat and @dcherian, please clarify if I should be switching to drop_vars or if I am going to run into issues yet again if I do so?

Yes yes I agree!

drop_vars would be a quick unblocking fix...

@dcherian - are you suggesting that @xylar change his downstream code to use drop_vars instead? drop_vars has been deprecated. I don't think that's the right response here.

Instead we should fix this bug. The docs for drop suggest that you should be able to provide a set as an input. Somehow we made that not work in the latest release.

How about drop_vars instead?

I believe a set() object should be a valid labels argument according to the documentation of drop(): http://xarray.pydata.org/en/v0.14.0/generated/xarray.Dataset.drop.html#xarray.Dataset.drop