I have N 1D xr.DataArray's with an 1 array coordinate b and 1 scalar coordinate a. I want to combine them to a 2D DataArray with array coordinates b, a. How to do this? I have tried:
x1 = xr.DataArray(np.arange(0,3)[...,np.newaxis], coords=[('b', np.arange(3,6)),('a', [10])]).squeeze()
x2 = xr.DataArray(np.arange(0,3)[...,np.newaxis], coords=[('b', np.arange(3,6)),('a', [11])]).squeeze()
xcombined = xr.concat([x1, x2])
xcombined
Results in :
<xarray.DataArray (concat_dims: 2, b: 3)>
array([[0, 1, 2],
[0, 1, 2]])
Coordinates:
* b (b) int64 3 4 5
a (concat_dims) int64 10 11
Dimensions without coordinates: concat_dims
Now I like to select a particularly 'a':
xcombined.sel(a=10)
However, this raises:
ValueError: dimensions or multi-index levels ['a'] do not exist
1 Answer
If you supply dim to concat, this works:
xcombined = xr.concat([x1, x2], dim='a')
And then:
xcombined.sel(a=10)
<xarray.DataArray (b: 3)>
array([0, 1, 2])
Coordinates:
* b (b) int64 3 4 5
a int64 10
