[R] problem applying a conditional formula to each element of a matrix
Dale Steele
dale.w.steele at gmail.com
Wed Dec 12 22:35:51 CET 2007
I'm applying a function (Cov.f) defined below to each element of a
distance matrix. When I run the code below, I get a warning message
(below) and elements of returned matrix [2,3] and [3,2] are not zero
as I would expect. Clearly, there is an error... What am I doing
wrong? Thanks. --Dale
Warning message:
In if (h <= phi) { :
the condition has length > 1 and only the first element will be used
# function
Cov.f <- function(h, sigmasq, phi) {
if (h <= phi) {Cij <- sigmasq * (1 - ( 1.5 * (h/phi) - 0.5 *
(h/phi)^3)) } else
if (h > phi) {Cij <- 0}
return(Cij)
}
x.coord <- c(5.7, 6.7, 9.8)
y.coord <- c(42.7, 10.2, 77.4)
coords <- cbind(x.coord, y.coord)
distance.matrix <- as.matrix(dist(coords, method="euclidean"))
distance.matrix
Cov.f(distance.matrix, 3.9, 58.1)
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