Euclidean distance of two vectors

Question

How do I find the Euclidean distance of two vectors:

x1 <- rnorm(30) x2 <- rnorm(30) 

Answer 1

Use the dist() function, but you need to form a matrix from the two inputs for the first argument to dist():

dist(rbind(x1, x2)) 

For the input in the OP's question we get:

> dist(rbind(x1, x2))         x1 x2 7.94821 

a single value that is the Euclidean distance between x1 and x2.

Answer 2

As defined on Wikipedia, this should do it.

euc.dist <- function(x1, x2) sqrt(sum((x1 - x2) ^ 2)) 

There's also the rdist function in the fields package that may be useful. See here.

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EDIT: Changed ** operator to ^. Thanks, Gavin.