On 30.10.2012 20:01, Omphalodes Verna wrote:
Hi all!
My question in about using mapply instead for loop. Below is a example with for
loop: Is it posible to give same results with mapply function?
Thanks for help!
OV
x <- 1:10
y <- 1:10
xyz <- data.frame(expand.grid(x,y)[1], expand.grid(x,y)[2], z = rnorm(100))
names(xyz) <- c("x", "y", "z")
head(xyz)
size <- 2
output <- NULL
### for loop
for(i in 1:dim(xyz)[1]){
x0 <- xyz[i, "x"]
y0 <- xyz[i, "y"]
xyzSel <- xyz[xyz$x >= (x0 - size) & xyz$x < (x0 + size) & xyz$y >= (y0 - size) &
xyz$y < (y0 + size), ]
output[i] <- min(xyzSel$z)
}
output
Yes:
output <- mapply(function(x0, y0)
min(xyz[(xyz$x >= (x0 - size) & xyz$x < (x0 + size)) & (xyz$y >=
(y0 - size) & xyz$y < (y0 + size)), "z"]),
xyz$x, xyz$y)
Uwe Ligges
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