import sys

def roll_lon(da_, lonname='lon'):
    "roll the input DataArray of global coverage data along the longitude dimention by 180 degree, e.g. from 0~360 to -180~180"
    da = da_.roll({lonname: da_[lonname].size//2}, roll_coords=True) #roll array
    if da[lonname].max() > 180:
        #0~360 to -180~180
        lon_new = da[lonname].where(da[lonname]<180, other=da[lonname]-360) #
    else:
        #-180-180 to 0-360
        lon_new = da[lonname].where(da[lonname]>180, other=da[lonname]+360) #
    da = da.assign_coords({lonname: lon_new})

    return da
        
def get_kws_from_argv(key, default=None):
    """get kws from sys.argv, e.g. daname=precip or --danme=precip """
    kws = [s for s in sys.argv if s.startswith(f'{key}=') or s.startswith(f'--{key}=')]
    if kws:
        value = kws[-1].split('=')[-1]
        print(f'{key}={value}')
    else:
        print(f'{key}={default}')
        value = default
    return value