Using xarray to calculate daily averages over multiple years

kial_average.py

import numpy as np
from netCDF4 import Dataset
import sys

import xarray
from xarray.ufuncs import *
from glob import glob
import os
import string


# Path to the files directories
directory = '/g/data1/v45/mom01_comparison/KDS75/'
start_index = 150
end_index = 158

file_paths=[]
for index in range(start_index, end_index+1):
    file_paths.extend(glob(os.path.join(directory,'output{:03d}'.format(index),'rregionoceankerg__*.nc')))

print 'Found ',len(file_paths),' files'

# Open the list of files as a single dataset
ds = xarray.open_mfdataset(file_paths, engine='netcdf4', chunks={'time':1,'st_ocean':11,'yu_ocean_sub01':133,'xu_ocean_sub01':515},decode_times=False,mask_and_scale=True)

ds["time"].attrs["units"] = 'days since 1900-01-01'
ds["time"].attrs["calendar_type"] = string.lower(ds["time"].attrs["calendar_type"]) 
ds["time"].attrs["calendar"] = string.lower(ds["time"].attrs["calendar"]) 

ds = xarray.decode_cf(ds,decode_times=True)
print ds["time"]

# attrs = {'units': 'days since 1700-01-01'}

mld = ds["mld"]

mldave = mld.groupby("time.month").mean(dim='time')

print mldave.shape