Explode an xarray Dataset coordinate into variables

[paw-lu]

Say I have an xarray DataSet like this:

Dimensions:             (chain: 1, draw: 2000, coefficients_dim_0: 3)
Coordinates:
  * chain               (chain) int64 0
  * draw                (draw) int64 0 1 2 3 4 5 ... 1995 1996 1997 1998 1999
  * coefficients_dim_0  (coefficients_dim_0) <U1 'a' 'b' 'c'
Data variables:
    coefficients        (chain, draw, coefficients_dim_0) float32 0.9644 ... ...
    e                   (chain, draw) float32 1.665 1.665 1.665 ... 1.665 1.665
Attributes:
    created_at:                 2024-01-27T00:52:26.920296
    arviz_version:              0.12.1
    inference_library:          pyro
    inference_library_version:  1.8.4

I want to "explode" the names for coefficients_dim_0 into their own variable names, something like

Dimensions:             (chain: 1, draw: 2000, coefficients_dim_0: 3)
Coordinates:
  * chain               (chain) int64 0
  * draw                (draw) int64 0 1 2 3 4 5 ... 1995 1996 1997 1998 1999
Data variables:
    a                   (chain, draw) float32 1.665 1.665 1.665 ... 1.665 1.665
    b                   (chain, draw) float32 1.665 1.665 1.665 ... 1.665 1.665
    c                   (chain, draw) float32 1.665 1.665 1.665 ... 1.665 1.665
    e                   (chain, draw) float32 1.665 1.665 1.665 ... 1.665 1.665
Attributes:
    created_at:                 2024-01-27T00:52:26.920296
    arviz_version:              0.12.1
    inference_library:          pyro
    inference_library_version:  1.8.4

[paw-lu]

Though of trying .reset_coords("coefficients_dim_0") but i get:

ValueError: cannot remove index coordinates with reset_coords: {'coefficients_dim_0'}

[dcherian]

How about https://docs.xarray.dev/en/stable/generated/xarray.DataArray.to_dataset.html

xr.merge([ds["e"], ds["coefficients"].to_dataset(dim="coefficients_dim_0")])

[paw-lu]

Perfect. Didn't know about to_dataset + dim here. Thank you so much!