harmonica.derivative_easting

harmonica.derivative_easting(grid, *, order=1, method='finite-diff', pad=True, pad_kwargs=None)

Calculate the derivative of a regular grid in the easting direction.

Compute the spatial derivative in the easting direction of regular gridded data. It can compute using accurate central differences using xarray.differentiate or through frequency domain calculations through Fast Fourier Transform.

Important

Choosing the finite differences option produces more accurate results without border effects.

Parameters:

gridxarray.DataArray

A two dimensional xarray.DataArray whose coordinates are evenly spaced (regular grid). Its dimensions should be in the following order: northing, easting. Its coordinates should be defined in the same units.

orderint, optional

The order of the derivative. Default to 1.

methodstr, optional

Method that will be used for computing the easting derivative. It can be either "finite-diff", for computing using xarray.differentiate, or "fft", for using FFT-based filters. Default "finite-diff".

padbool, optional

If True, will add padding to the grid before taking the Fourier Transform and applying the filter and remove it after the inverse Fourier Transform. Adding padding usually helps reduce edge effects from signal truncation. Default is True.

pad_kwargsdict or None, optional

Any additional keyword arguments that should be passed to the xarray.DataArray.pad function in the form of a dictionary. If none are given, the default padding of 25% the dimensions of the grid will be added using the “edge” method.

Returns:

derivativexarray.DataArray

A xarray.DataArray with the easting derivatives of the passed grid. Its units are the same units of the grid per units of its coordinates to the power of the passed order.

See also

harmonica.filters.derivative_easting_kernel

References

[Blakely1995]