import xarray as xa
import numpy as np
import sys

fns='aice_12.nc aice_13.nc aice_14.nc'.split()
reg = 'REGION'
latb  = 66.
late  = 75.
lonb  = -25.
lone  = -12.
var = 'aice'


if lonb < 0: lonb += 360
if lone < 0: lone += 360

gridds = xa.open_dataset(fns[0])
print(gridds)
wgt = gridds.tarea
lat = gridds.TLAT
lon = gridds.TLON
lon = lon.where(lon>0, lon+360) ## 0-360

wgt = wgt.where(latb<lat ,0)
wgt = wgt.where(late>lat ,0)
wgt = wgt.where(lonb<lon ,0)
wgt = wgt.where(lone>lon ,0)
wgt.name = 'weighting'
wgt.to_netcdf(f'{reg}_weighting.nc')  ## save for plot

for fn in fns:
    n = fn[-5:-3]
    ofn = f'{var}_{n}_{reg}_ts.nc'
    ds = xa.open_dataset(fn)
    dd = ds[var].weighted(wgt)
    ovar  = dd.mean(('nj','ni'),skipna=True)
    ovar.to_netcdf(ofn)