extractIndex function

Indexing to extract values of a Raster* object

These are shorthand methods that call other methods that should normally be used, such as getValues, extract, crop.

object[i] can be used to access values of a Raster* object, using cell numbers. You can also use row and column numbers as index, using object[i,j] or object[i,] or object[,j]. In addition you can supply an Extent, SpatialPolygons, SpatialLines or SpatialPoints object.

If drop=TRUE (the default) cell values are returned (a vector for a RasterLayer, a matrix for a RasterStack or RasterBrick). If drop=FALSE a Raster* object is returned that has the extent covering the requested cells, and with all other non-requested cells within this extent set to NA.

If you supply a RasterLayer, its values will be used as logical (TRUE/FALSE) indices if both Raster objects have the same extent and resolution; otherwise the cell values within the extent of the RasterLayer are returned.

Double brackes '[[ ]]' can be used to extract one or more layers from a multi-layer object. methods

Methods

See Also

getValues, setValues, extract, crop, rasterize

Examples

r <- raster(ncol=10, nrow=5)
values(r) <- 1:ncell(r) 

r[1]
r[1:10]
r[1,]
r[,1]
r[1:2, 1:2]

s <- stack(r, sqrt(r))
s[1:3]
s[[2]]