Classes for global gridded data.

## Subclasses

Subclass name Description
DHRealGrid Class for real Driscoll and Healy (1994) sampled grids.
DHComplexGrid Class for complex Driscoll and Healy (1994) sampled grids.
GLQRealGrid Class for real Gauss-Legendre quadrature sampled grids.
GLQComplexGrid Class for complex Gauss-Legendre quadrature sampled grids.

## Initialization

Initialization method Description
x = SHGrid.from_array() Initialize using an array.
x = SHGrid.from_xarray() Initialize using an xarray DataArray.
x = SHGrid.from_netcdf() Initialize using a netcdf file or object.
x = SHGrid.from_file() Initialize using an array from a file.
x = SHGrid.from_zeros() Initialize using an array of zeros.
x = SHGrid.from_cap() Initialize using a rotated spherical cap.
x = SHGrid.from_ellipsoid() Initialize using a triaxial ellipsoid.

## Class attributes

Attribute Description
data Array of the gridded data.
nlat, nlon The number of latitude and longitude bands in the grid.
n The number of samples in latitude for 'DH' grids.
lmax The maximum spherical harmonic degree that can be resolved by the grid sampling.
sampling The longitudinal sampling for Driscoll and Healy grids. Either 1 for equally sampled grids (nlon = nlat) or 2 for equally spaced grids in degrees.
kind Either 'complex' or 'real' for the data type.
grid Either 'DH' or 'GLQ' for Driscoll and Healy grids or Gauss-Legendre quadrature grids.
units The units of the gridded data.
zeros The $$\cos(\theta)$$ nodes used with Gauss-Legendre quadrature grids. Default is None.
weights The latitudinal weights used with Gauss-Legendre quadrature grids. Default is None.
extend True if the grid contains the redundant column for 360 E and (for 'DH' grids) the unnecessary row for 90 S.

## Class methods

Method Description
to_array() Return a numpy array of the gridded data.
to_xarray() Return the gridded data as an xarray DataArray.
to_netcdf() Return the gridded data as a netcdf formatted file or object.
to_file() Save raw gridded data to a text or binary file.
to_real() Return a new SHGrid class instance of the real component of the data.
to_imag() Return a new SHGrid class instance of the imaginary component of the data.
lats() Return a vector containing the latitudes of each row of the gridded data.
lons() Return a vector containing the longitudes of each column of the gridded data.
histogram() Return an area-weighted histogram of the gridded data.
expand() Expand the grid into spherical harmonics.
min() Return the minimum value of data.
max() Return the maximum value of data.
copy() Return a copy of the class instance.
plot() Plot the data.
plotgmt() Plot projected data using the generic mapping tools (GMT).
plot3d() Plot a 3-dimensional representation of the data.
info() Print a summary of the data stored in the SHGrid instance.