python-xarray: open_mfdataset concat along two dimensions

Question

I have files which are made of 10 ensembles and 35 time files. One of these files looks like:

>>> xr.open_dataset(\'ens1/CCSM4_ens1_07ic_19820701-19         


        

Answer 1

xarray.open_mfdataset does not support 2d merges. What you will need to do is use concat along the second dimension:

import os
import xarray as xr

ens_list = []
for num in range(1, 11):
     ens = 'ens%d' % num
     ens_list.append(xr.open_mfdataset(os.path.join(ens, '*NPac*')))
ds = xr.concat(ens_list, dim='ensemble')

This is a common problem that xarray users run into. It is quite difficult, however, to write a generalized ND concat routine.