issue_comments: 326754319

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https://github.com/pydata/xarray/issues/1521#issuecomment-326754319 https://api.github.com/repos/pydata/xarray/issues/1521 326754319 MDEyOklzc3VlQ29tbWVudDMyNjc1NDMxOQ== 6213168 2017-09-02T16:24:56Z 2017-09-02T16:24:56Z MEMBER

Getting closer. The problem is in xarray.concat, which resolves non-index dask coords, TWICE, even if it should not resolve them at all (as alignment should be done on index coords only?)

``` import xarray import numpy import dask.array

def kernel(label): print("Kernel [%s] invoked!" % label) return numpy.array([1, 2])

a = dask.array.Array(name='a', dask={('a', 0): (kernel, 'a')}, chunks=((2, ), ), dtype=int) b = dask.array.Array(name='b', dask={('b', 0): (kernel, 'b')}, chunks=((2, ), ), dtype=int)

ds0 = xarray.Dataset(coords={'x': ('x', [1, 2]), 'y': ('x', a)}) ds1 = xarray.Dataset(coords={'x': ('x', [1, 2]), 'y': ('x', b)}) xarray.concat([ds0, ds1], dim='z') Output: Kernel [a] invoked! Kernel [b] invoked! Kernel [b] invoked!Kernel [a] invoked!

<xarray.Dataset> Dimensions: (x: 2) Coordinates: * x (x) int64 1 2 y (x) int64 dask.array<shape=(2,), chunksize=(2,)> Data variables: empty ```

 
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