Label row and column titles with units

According to this plotting example, xlabels and ylabels are labeled with units. However, row labels and column labels omit the units.

MCVE Code Sample

import xarray as xr
ds = xr.tutorial.scatter_example_dataset()
ds.plot.scatter(x='A', y='B', col='x', row='z', hue='w', hue_style='discrete')

Expected Output

Should xr.FacetGrid include the functionality for plotting row labels and column labels when provided?

Problem Description

It could be solved with the following included in plot/facetgrid.py#L486:

if self.data[self._row_var].attrs.get('units'):
   units =  self.data[self._row_var].attrs['units']   
   template="{coord} = {value} [{units}]"

title = nicetitle(coord=self._row_var, value=row_name, \
                          maxchar=maxchar, template = template, units = unit

and with the following included in plot/facetgrid.py#L499:

if self.data[self._col_var].attrs.get('units'):
   units =  self.data[self._col_var].attrs['units']   
   template="{coord} = {value} [{units}]"

title = nicetitle(coord=self._col_var, value=col_name, \
                          maxchar=maxchar, template = template, units = units)

and with the modification of _nicetitle:

def _nicetitle(coord, value, maxchar, template, units = None):
    """
    Put coord, value in template and truncate at maxchar
    """
    prettyvalue = format_item(value, quote_strings=False)
    if units is not None:
        title = template.format(coord=coord, value=prettyvalue, units = units)
    else:
        title = template.format(coord=coord, value=prettyvalue)

    if len(title) > maxchar:
        title = title[: (maxchar - 3)] + "..."

    return title

Output of xr.show_versions()

Read plot/facetgrid.py around the row and column title handling at the linked lines, then run the MCVE using scatter_example_dataset(). Confirm that row and column labels include their coordinates' units when available, while existing labels without units continue to work.