Detrend xarray DataArrays using polyfit

detrend_xarray.py

import xarray as xr

def detrend_dim(da, dim, deg=1):
    # detrend along a single dimension
    p = da.polyfit(dim=dim, deg=deg)
    fit = xr.polyval(dim, p.polyfit_coefficients)
    return da - fit

def detrend(da, dims, deg=1):
    # detrend along multiple dimensions
    # only valid for linear detrending (deg=1)
    da_detrended = da
    for dim in dims:
        da_detrended = detrend_dim(da_detrended, dim, deg=deg)
    return da_detrended

Hey! This was a useful snippet of code for easy detrending, but I just wanted to say that it doesn't work as it is — when you pass 'dim' to xarray.polyval, it only reads a string, but it needs a coordinate type. I made it work by changing line 6 to:

fit = xr.polyval(da[dim], p.polyfit_coefficients)

Thanks for sharing!

Hello!!!
I would like to know how to adjust the polynomial to remove the non-linear trend using xarray... Does anyone have any suggestions? I'm new to python

Thanks!

Hi, how to apply this function to xarray dataset?