a workaround for achieving this would be to use the apply method of xarray data structures along with the expand_dims method. Here's an example of how we can use it:

``` import xarray as xr dataset = xr.Dataset(data_vars={'foo': 1, 'bar': 2})

Define a function that expands the given variable along a new dimension

def expand_variable(da): if da.name == 'foo': return da.expand_dims('zar') else: return da

Use the apply method to apply the function to only the desired variables

expanded_dataset = dataset.apply(expand_variable, keep_attrs=True)

print(expanded_dataset)

``` Here, the expand_variable function is defined to only expand the variable with the name 'foo' along a new dimension. The apply method is used to apply this function to each data variable in the dataset, but only 'foo' is actually modified.