import xarray as xr
import numpy as np

data = xr.DataArray(np.random.randn(2, 3), coords={'x': ['a', 'b']}, dims=('y', 'x'))
ds = xr.Dataset({'foo': data})

# Applied on the Dataset
ds.to_dataframe()

#          foo
#x y          
#a 0  0.348519
#  1 -0.322634
#  2 -0.683181
#b 0  0.197501
#  1  0.504810
#  2 -1.871626

# Applied to the DataArray
ds['foo'].to_dataframe()

#          foo
#y x          
#0 a  0.348519
#  b  0.197501
#1 a -0.322634
#  b  0.504810
#2 a -0.683181
#  b -1.871626