apply() is slow - how to make it faster or what are my alternatives?

Question

I have a quite large data frame, about 10 millions of rows. It has columns x and y, and what I want is to compute

hypot <- funct         


        

Answer 1

R is vectorised, so you could use the following, plugging in your own matrix of course

X = t(matrix(1:4, 2, 2))^2
>      [,1] [,2]
 [1,]    1    4
 [2,]    9   16

rowSums(X)^0.5

Nice and efficient :)