issue_comments: 524617139

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https://github.com/pydata/xarray/issues/3240#issuecomment-524617139 https://api.github.com/repos/pydata/xarray/issues/3240 524617139 MDEyOklzc3VlQ29tbWVudDUyNDYxNzEzOQ== 2818208 2019-08-25T10:02:39Z 2019-08-25T10:02:39Z CONTRIBUTOR

I see. This is because coordinates are just DataArray objects. So

```python

arr.coords['y'] = range(3) ```

is equivalent to

```python

new_coords = xr.DataArray(data=range(3)) arr.coords['y'] = new_coords ```

And the reason this is a ValueError is that new_coords has a default dimension dim_0 that is not on arr. However, this

```python

arr.coords['y'] = 1 ```

is equivalent to...

```python

new_coords = xr.DataArray(data=1, dims=[]) arr.coords['y'] = new_coords ```

And new_coords has no dimensions that are not on arr.

 
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