View source: R/overlap.weight.R
overlap.weight | R Documentation |
Weight raster cells by overlapping polygons to avoid over-counting when aggregating by polygons
overlap.weight(raster, polygons, count = FALSE, warn = TRUE)
raster |
a RasterLayer object. |
polygons |
a SpatialPolygons, SpatialPolygonsDataFrame, or simple feature
collection with at least two features. The function will still work with only
one polygon, but values will be unchanged, and the result will be equivalent
to |
count |
a logical indicating whether to return a raster with the count of polygons intersecting each cell, or a raster with original values weighted by 1/number of intersecting polygons. |
warn |
include warnings? Most common is that the returned raster will be
an intersection of the raster and the polygons. Default |
This function takes a raster and a set of polygons as arguments.
It counts the number of polygons that intersect each raster cell. It can
return either a raster with the count of the number of intersecting polygons
as cell values or the original raster with cell values weighted by 1 / the
number of intersecting polygons (the default behavior). Cells that do not
intersect any polygons will receive a value of NA
. If the extent of the
polygons is less than the extent of the raster, then the function will warn
that it is cropping the raster to the polygons' extent.
a RasterLayer object.
library(sf) library(raster) polys_t <- st_sfc(list(st_polygon(list(rbind(c(2,2), c(2,6), c(6,6), c(6,2), c(2, 2)))), st_polygon(list(rbind(c(8,8), c(4,8), c(4,4), c(8,4), c(8,8))))), crs = st_crs('OGC:CRS84')) raster_t <- raster(nrows = 10, ncols = 10, xmn = 0, xmx = 10, ymn = 0, ymx = 10, vals = 1:100, crs = CRS(st_crs(polys_t)$proj4string)) overlap.weight(raster_t, polys_t)
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