html_url,issue_url,id,node_id,user,created_at,updated_at,author_association,body,reactions,performed_via_github_app,issue
https://github.com/pydata/xarray/issues/3068#issuecomment-508853564,https://api.github.com/repos/pydata/xarray/issues/3068,508853564,MDEyOklzc3VlQ29tbWVudDUwODg1MzU2NA==,1217238,2019-07-05T20:15:27Z,2019-07-05T20:15:27Z,MEMBER,"> For the long term, I also understand that there isn't really a good way to check equality of two dask arrays. I wonder if dask's graph optimization could be used to ""simplify"" two dask arrays' graph separately and check the graph equality. For example, two dask arrays created by doing `da.zeros((10, 10), chunks=2) + 5` should be theoretically equal because their dask graphs are made up of the same tasks.

Dask actually already does this canonicalization. If two arrays have the same `name`, they use the same dask graph, e.g.,
```
In [5]: x = da.zeros((10, 10), chunks=2) + 5

In [6]: y = da.zeros((10, 10), chunks=2) + 5

In [7]: x.name
Out[7]: 'add-f7441a0f46f5cf40458391cd08406c23'

In [8]: y.name
Out[8]: 'add-f7441a0f46f5cf40458391cd08406c23'
```

So xarray could safely look at `.name` on dask arrays (e.g., inside `Variable.equals` or `duck_array_ops.array_equiv`) for determining that two dask arrays are the same, rather than merely using `is` to check if they are the same objects.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,462859457
https://github.com/pydata/xarray/issues/3068#issuecomment-507480052,https://api.github.com/repos/pydata/xarray/issues/3068,507480052,MDEyOklzc3VlQ29tbWVudDUwNzQ4MDA1Mg==,1217238,2019-07-02T01:15:36Z,2019-07-02T01:15:36Z,MEMBER,"The source of the problem here is that when combining objects, xarray needs to decide what coordinates should remain. Our current heuristic, which pre-dates dask support, was really designed for array in memory: we keep around coordinates if they are equal on both arguments, and remove them otherwise. In some cases we can avoid the computation, if we know that the coordinates are the same object.

I am open to ideas on how to make this work better.","{""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,462859457