Hi guys. Another thing I cannot vectorize:
I have an array "a", of size 5-by-2, for example, of 5 2D vectors. I
also have a distance function that computes the distance between two
vectors (usual Euclidean distance is a good example but I have other metrics I
want to use as well). I want a 5-by-5 array with the [i,j]th element being
the distance from a[i,] to a[j,]
To Wit:
a <- matrix(1:10,5,2)
array <- matrix(NA, 5, 5)
dist <- function(x1,x2){sqrt(sum(x1-x2)^2)}
#NONVECTORIZED BIT FOLLOWS
for(i in 1:5) {
for(j in 1:5) {
array[i,j] <- dist(a[i,] , a[j,])
}
}
(note that array[i,i]=0 for i=1:5 as expected).
How to vectorize this?
--
Robin Hankin
Uncertainty Analyst
Southampton Oceanography Centre
SO14 3ZH
tel +44(0)23-8059-7743
[EMAIL PROTECTED] (edit in obvious way; spam precaution)
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