issue_comments: 415647225

It might make sense to use a list instead of a set here. On Thu, Aug 23, 2018 at 8:37 PM Keisuke Fujii notifications@github.com wrote:

@fujiisoup commented on this pull request.

Thanks. A few comments.

In xarray/core/dataset.py https://github.com/pydata/xarray/pull/2375#discussion_r212513643:

+ + missing_dims = [dim for dim in dims if dim not in self.dims] + if missing_dims: + raise ValueError('Dataset does not contain the dimensions: %s' + % missing_dims) + + non_multi_dims = [dim for dim in dims + if not isinstance(self.get_index(dim), pd.MultiIndex)] + if non_multi_dims and dim_from_kwarg: + raise ValueError('cannot unstack dimensions that do not ' + 'have a MultiIndex: %s' % non_multi_dims) + + dims = dims - set(non_multi_dims) + if len(dims) == 0: + raise ValueError('cannot unstack an object that does not have ' + 'MultiIndex dimensions')

I think that we can allow to unstack an object without MultiIndex, which just returns as is. It would be useful if users want to remove any MultiIndexes from an object.

---

In xarray/core/dataset.py https://github.com/pydata/xarray/pull/2375#discussion_r212513859:

• ---

• unstacked : Dataset
• Dataset with unstacked data. +
• See also

• ---

• Dataset.stack
• """
• dim_from_kwarg = dim is not None +
• if isinstance(dim, basestring):
• dims = set([dim])
• elif dim is None:
• dims = set(self.dims)
• else:
• dims = set(dim)

Maybe we can use OrderedSet instead of set so that the resultant dimension order is fixed.

— You are receiving this because you commented. Reply to this email directly, view it on GitHub https://github.com/pydata/xarray/pull/2375#pullrequestreview-149165031, or mute the thread https://github.com/notifications/unsubscribe-auth/ABKS1k4sM5-2xSpTAI02Sa792Zqido7eks5uT3TggaJpZM4WGc2s .