[R] Vectorization in a random order

[Richard M. Heiberger]

nBuyMat <- data.frame(matrix(rnorm(28), 7, 4))
nBuyMat
nBuy <- nrow(nBuyMat)
sample(1:nBuy, nBuy, replace=FALSE)
sample(1:nBuy)
sample(nBuy)
?sample
apply(nBuyMat[sample(1:nBuy,nBuy, replace=FALSE),], 1, function(x) sum(x))

apply(nBuyMat[sample(nBuy),], 1, function(x) sum(x))


The defaults for sample do what you have requested.

If the original row identification matters, then be sure the to use
either a matrix with rownames or a data.frame.

Rich


Sent from my iPhone

> On Nov 10, 2016, at 08:06, Thomas Chesney <Thomas.Chesney at nottingham.ac.uk> wrote:
>
> for (b in sample(1:nBuy,nBuy, replace=FALSE)){
>
> }
>
> but
>
> apply(nBuyMat, 1, function(x))