issue_comments: 124192448

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https://github.com/pydata/xarray/issues/490#issuecomment-124192448 https://api.github.com/repos/pydata/xarray/issues/490 124192448 MDEyOklzc3VlQ29tbWVudDEyNDE5MjQ0OA== 1217238 2015-07-23T18:16:06Z 2015-07-23T18:16:06Z MEMBER

I agree, this would be useful. Probably should take a dim argument that specifies the dimension along which to take the differences.

I guess x.diff('x') would do something like the following?

``` python In [28]: x = xray.Dataset({'foo': ('x', [5, 5, 6, 6])})

In [29]: start = x.isel(x=slice(None, -1))

In [30]: end = x.isel(x=slice(1, None))

In [31]: start.coords['x'] = end.coords['x']

In [32]: end - start Out[32]: <xray.Dataset> Dimensions: (x: 3) Coordinates: * x (x) int64 1 2 3 Data variables: foo (x) int64 0 1 0 ```

Since this logic is the same for Dataset and DataArray objects, it could live as a method on BaseDataObject in xray/core/common.py: https://github.com/xray/xray/blob/v0.5.2/xray/core/common.py#L147

If you find yourself needing to write dataset or dataarray specific logic, write it as a Dataset method and follow the example of DataArray.swap to extend it to dataarrays: https://github.com/xray/xray/blob/v0.5.2/xray/core/dataarray.py#L659

 
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