issues: 228023777

Trying to index a Dataset using an index array of dtype uint64 yields a ValueError. int64 works fine. See below:

``` In [13]: import xarray

In [14]: ds = xarray.Dataset({"A": (("x", "y"), arange(5*6).reshape(5,6))})

In [15]: ds[{"x": numpy.array([0], dtype="int64")}] Out[15]: <xarray.Dataset> Dimensions: (x: 1, y: 6) Dimensions without coordinates: x, y Data variables: A (x, y) int64 0 1 2 3 4 5

In [16]: ds[{"x": numpy.array([0], dtype="uint64")}]

ValueError Traceback (most recent call last) <ipython-input-16-4cf23af0967e> in <module>() ----> 1 ds[{"x": numpy.array([0], dtype="uint64")}]

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/dataset.py in getitem(self, key) 722 """ 723 if utils.is_dict_like(key): --> 724 return self.isel(**key) 725 726 if hashable(key):

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/dataset.py in isel(self, drop, indexers) 1147 for name, var in iteritems(self._variables): 1148 var_indexers = dict((k, v) for k, v in indexers if k in var.dims) -> 1149 new_var = var.isel(var_indexers) 1150 if not (drop and name in var_indexers): 1151 variables[name] = new_var

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/variable.py in isel(self, **indexers) 547 if dim in indexers: 548 key[i] = indexers[dim] --> 549 return self[tuple(key)] 550 551 def squeeze(self, dim=None):

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/variable.py in getitem(self, key) 377 dims = tuple(dim for k, dim in zip(key, self.dims) 378 if not isinstance(k, integer_types)) --> 379 values = self._indexable_data[key] 380 # orthogonal indexing should ensure the dimensionality is consistent 381 if hasattr(values, 'ndim'):

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/indexing.py in getitem(self, key) 467 468 def getitem(self, key): --> 469 key = self._convert_key(key) 470 return self._ensure_ndarray(self.array[key]) 471

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/indexing.py in _convert_key(self, key) 454 if any(not isinstance(k, integer_types + (slice,)) for k in key): 455 # key would trigger fancy indexing --> 456 key = orthogonal_indexer(key, self.shape) 457 return key 458

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/indexing.py in orthogonal_indexer(key, shape) 78 """ 79 # replace Ellipsis objects with slices ---> 80 key = list(canonicalize_indexer(key, len(shape))) 81 # replace 1d arrays and slices with broadcast compatible arrays 82 # note: we treat integers separately (instead of turning them into 1d

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/indexing.py in canonicalize_indexer(key, ndim) 66 return indexer 67 ---> 68 return tuple(canonicalize(k) for k in expanded_indexer(key, ndim)) 69 70

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/indexing.py in <genexpr>(.0) 66 return indexer 67 ---> 68 return tuple(canonicalize(k) for k in expanded_indexer(key, ndim)) 69 70

/dev/shm/gerrit/venv/stable-3.5/lib/python3.5/site-packages/xarray/core/indexing.py in canonicalize(indexer) 63 'array indexing; all subkeys must be ' 64 'slices, integers or sequences of ' ---> 65 'integers or Booleans' % indexer) 66 return indexer 67

ValueError: invalid subkey array([0], dtype=uint64) for integer based array indexing; all subkeys must be slices, integers or sequences of integers or Booleans ```