terra (version 0.2-9)

extract: Extract values from a SpatRaster

Description

Extract values from a SpatRaster for the locations of a SpatVector

Usage

# S4 method for SpatRaster,SpatVector
extract(x, y, fun="", ...)
# S4 method for SpatRaster,matrix
extract(x, y, ...)

Arguments

x

SpatRaster

y

SpatVector (for points, lines, polygons), or 2-column matrix (x, y; for points)

fun

character. function to summarize the data. Currently ignored

...

additional arguments. None implemented

Value

data.frame

See Also

values

Examples

# NOT RUN {
r <- rast(ncol=5, nrow=5, xmin=0, xmax=5, ymin=0, ymax=5)
values(r) <- 1:25
xy <- rbind(c(0.5,0.5), c(2.5,2.5))
p <- vect(xy)

extract(r, xy)
extract(r, p)

r[1,]
r[5]
r[,5]

r[c(0:2, 99:101)]

f <- system.file("exdata/test.tif", package="terra")
r <- rast(f)

xy <- cbind(179000, 330000)
xy <- rbind(xy-100, xy, xy+1000)
extract(r, xy)

p <- vect(xy)
g <- geom(p)
g

extract(r, p)

x <- r + 10
extract(x, p)

i <- cellFromXY(r, xy)
x[i]
r[i]

y <- c(x,x*2,x*3)
y[i]

# extract with a polygon
f <- system.file("exdata/lux.shp", package="terra")
v <- vect(f)
z <- rast(v)
values(z) <- 1:100
e <- extract(z, v)
e[1:2]
rapply(e, mean)

x <- c(z, z*2, z/3)
e <- extract(x, v)
matrix(rapply(e, mean), ncol=nlyr(x), byrow=TRUE)
# }