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calc_history
2006 Jan 23
1
formatC slow? (or how can I make this function faster?
...oblems doing this in a speedy way. The simplest solution
(calc_history below, using apply, paste and collapse) takes about 2
seconds for a 10,000 x 10 matrix. I thought perhaps paste might be
building up the string in an efficient manner, so I tried using matrix
multiplication and formatC (as in calc_history2). This is about 25%
faster, but still seems slow.
smp <- matrix(rbinom(100000, 1, 0.5), nrow=10000)
calc_history <- function(smp) {
apply(smp, 1, paste, collapse="")
}
calc_history <- function(smp) {
mul <- 10 ^ ((ncol(smp)-1):0)
as.vector(formatC(smp %*% mul, format=&q...