bnspatial (version 1.1.1)

extractByMask: Extract raster values by mask

Description

This function extracts the values from a given input raster based on a mask.

Usage

extractByMask(layer, msk, spatial = FALSE, rast = NULL)

Arguments

layer

an object of class "RasterLayer" (package raster). The raster from which data will be extracted

msk

an object of class "RasterLayer" or a two column matrix of coordinates. The reference raster (or coordinates) to be used as mask for extraction.

spatial

logical. Should the output be spatially explicit -i.e. a georeferenced raster? Default is FALSE, returning a vector of extracted values from rast. If TRUE an object of class "RasterLayer" is returned.

rast

deprecated, use layer instead.

Value

a vector, or an object of class "RasterLayer". The values from the input raster (rast argument) at coordinates provided as matrix, or those overlapping with non NA cells in the mask raster. If spatial == TRUE an object of class "RasterLayer" is returned.

Details

When input data given to rast does not match the resolution and extent of a raster mask argument, the latter is preferred. The function will therefore return a vector of n elements, one for each non NA cell in the mask. Input raster cells falling inside mask cells, but not over their cells centre will be ignored.

See Also

aoi

Examples

# NOT RUN {
data(ConwyData)
list2env(ConwyData, environment())

m <- aoi(msk=ConwyLU, mskSub=c(2,3))
head( extractByMask(ConwySlope, msk=m), 20) 

# Extract making a raster
library(raster)
plot( extractByMask(ConwySlope, msk=m, spatial=TRUE) )
# }