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Efficient way to Calculate the squared distances for a set ofvectors to a fixed vector

Enrico Schumann 
You could do something like this:

# data
nrows <- 20000L
ncols <- 5L
myVec <- array(rnorm(nrows * ncols), dim = c(nrows, ncols))
y <- rnorm(ncols)

temp <- t(myVec) - y
result <- colSums(temp * temp)

# check
all.equal(as.numeric(crossprod(myVec[1L, ] - y)), result[1L])
#...

(And don't use a data.frame, but a matrix.)

regards,
Enrico

Thread (4 messages)

Wei Wu Efficient way to Calculate the squared distances for a set of vectors to a fixed vector Aug 23 Daniel Malter Efficient way to Calculate the squared distances for a set of vectors to a fixed vector Aug 23 Enrico Schumann Efficient way to Calculate the squared distances for a set ofvectors to a fixed vector Aug 23 Tsjerk Wassenaar Efficient way to Calculate the squared distances for a set ofvectors to a fixed vector Aug 24