stilt.geometry.overlap_weights

stilt.geometry.overlap_weights(geometry, x_centers, y_centers, xres, yres, crs, *, backend='auto')

Sparse (n_cells, ny * nx) fraction of each raster cell inside each cell.

The raster is described by its cell-centre axes, resolution and CRS; its cells are flattened y-outer / x-inner (the order of data.transpose("time", y, x).reshape(nt, -1)). geometry is reprojected to the raster CRS when needed. Results are cached on the (raster, geometry, backend) triple so repeated aggregations are a single matmul.

Polygon overlaps (Mesh, and Grid in another CRS) use exactextract when it is installed (backend="auto", roughly 100x faster on large rasters) and fall back to shapely otherwise. It is not a dependency; pip install exactextract enables it. Both backends give the same fractions.

Return type:

csr_matrix

Parameters:

• geometry (Grid | Mesh | Zones)

• x_centers (ndarray)

• y_centers (ndarray)

• xres (float)

• yres (float)

• crs (str)

• backend (Literal['auto', 'shapely', 'exactextract'])