Produce Regular Grid Matrix

Produce the grid used by persp, contour, etc, as an N x 2 matrix. This is really outdated by expand.grid() nowadays.

xy.grid(x, y)

Arguments

x,y

any vectors of same mode.

Value

a 2-column matrix of “points” for each combination of x and y, i.e. with length(x) * length(y) rows.

Author

Martin Maechler, 26 Oct 1994.

See also

expand.grid which didn't exist when xy.grid was first devised.

Examples

plot(xy.grid(1:7, 10*(0:4)))


x <- 1:3 ;  y <- 10*(0:4)
xyg <- xy.grid(x,y)

## Compare with expand.grid() :
m2 <- as.matrix(expand.grid(y,x)[, 2:1])
dimnames(m2) <- NULL
stopifnot(identical(xyg, m2))