Build aggregation table — build_aggregation_table • mbg

Build a table to quickly aggregate from pixels to polygons

Usage

build_aggregation_table(polygons, id_raster, polygon_id_field, verbose = FALSE)

Arguments

polygons: terra::SpatVector object. Should contain a unique ID field.
id_raster: terra::SpatRaster object. ID raster created by build_id_raster() for the polygons object. Should have the same CRS as polygons and completely cover it.
polygon_id_field: (character(1)) Unique identifier field in polygons.
verbose: (logical(1), default FALSE) Show progress for building aggregation rows for each polygon?

Value

data.table with fields:

polygon_id: Unique polygon identifier
pixel_id: unique pixel ID from the ID raster
masked_pixel_id: Index counting only non-NA pixels from the ID raster
area_fraction: fraction of the pixel area falling within this polygon
Merged fields from the table of polygons

See also

calculate_pixel_fractions_single_polygon()

Examples

if (FALSE) { # \dontrun{
  polygons <- sf::st_read(system.file('extdata/Benin_communes.gpkg', package = 'mbg'))
  id_raster <- build_id_raster(polygons)
  aggregation_table <- build_aggregation_table(
    polygons, id_raster, polygon_id_field = 'commune_code'
  )
} # }