On 2011-04-23 03:42, John Kane wrote:
I KNEW there was a better way!
--- On Wed, 4/20/11, Jeremy Hetzel<jthet...@gmail.com> wrote:
From: Jeremy Hetzel<jthet...@gmail.com>
Subject: Re: [R] Random Relabelling
To: r-help-arch...@googlegroups.com
Cc: r-help@r-project.org, "Kevin Matthews"<kevin-matth...@uiowa.edu>
Received: Wednesday, April 20, 2011, 2:25 PM
Kevin,
The following follows John's suggestion, but without the
loop. It's quick
for me.
Jeremy
Jeremy T. Hetzel
Boston University
## Generate sample data
n<- 4000
rep<- 1000
rate<- rnorm(n, mean = 15, sd = 2) / 100000 # Mortality
rates around
15/100k
## Create an empty matrix with appropriate dimensions
permutations<- matrix(ncol = n, nrow = rep)
## Use apply() to resample
permutations<- apply(permutations, 1, function(x)
{
sample(rate, size = n, replace = F)
})
## Look at the matrix
dim(permutations)
head(permutations)
## Find the column means
means<- apply(permutations, 1, mean)
means
And you might note that
means <- rowMeansy(permutations)
is about 10-15 times faster (if speed matters).
Peter Ehlers
[...snipped...]
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