Coordinate type changing from string to object

[seth-p]

Originally posted on https://groups.google.com/forum/#!topic/xarray/4k8ZAx998UU. I would expect [2], [3], and [4] to produce identical results, with coordinate xyz being of type |S1 (in general |Sn where n is minimal to accommodate the coordinate values), not object. This behavior is observed with xarray versions 0.8.2 and 0.9.1.

Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 27 2016, 15:24:40) [MSC v.1500 64 bit (AMD64)]
Type "copyright", "credits" or "license" for more information.

IPython 5.1.0 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: from xarray import DataArray

In [2]: DataArray([1.], dims=('xyz',), coords={'xyz': ['a']}) + \
   ...: DataArray([5.], dims=('xyz',), coords={'xyz': ['a']})
Out[2]:
<xarray.DataArray (xyz: 1)>
array([ 6.])
Coordinates:
  * xyz      (xyz) |S1 'a'

In [3]: DataArray([1., 2.], dims=('xyz',), coords={'xyz': ['a', 'b']}) + \
   ...: DataArray([5.], dims=('xyz',), coords={'xyz': ['a']})
Out[3]:
<xarray.DataArray (xyz: 1)>
array([ 6.])
Coordinates:
  * xyz      (xyz) object 'a'

In [4]: DataArray([1.], dims=('xyz',), coords={'xyz': ['a']}) + \
   ...: DataArray([5., 6.], dims=('xyz',), coords={'xyz': ['a', 'b']})
Out[4]:
<xarray.DataArray (xyz: 1)>
array([ 6.])
Coordinates:
  * xyz      (xyz) object 'a'

[stale]

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[seth-p]

I think this is still an issue.

[kmuehlbauer]

Works with latest xarray 2024.10.0. Please reopen with updated examples if this is still an issue.