On 29.Jul.2008, at 14:13, ONKELINX, Thierry wrote:
Dear Frederike,
#Both your functions are vectorized. So you don't need loops. Working
with vectorized functions is much faster than looping.
fn <- function (x,y) {
ifelse(x>46 & x<52 & y<12, 1, 0)
}
datagrid <- expand.grid(i = 40:60, j = 0:20)
res <- apply(datagrid, 1, function(z){
fn(z["i"], z["j"])
})
or
outer(40:60,0:20,fn2)
which also keeps the matrix structure ...
(use as.vector(...) or as.vector(t(...)) if you need a vector)
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