Here is one way of doing it:
x - data.frame(group=sample(1:4,100,TRUE), age=runif(100,4,80))
tapply(x$age, x$group, function(z) mean(z[sample(seq_along(z), length(z) /
10)]))
1234
34.56628 58.70901 54.26239 58.89306
On Wed, Mar 5, 2008 at 7:49 PM, Chang Liu
You don't need any explicit loops at all. Here is a demo of one way to
do it:
set.seed(23) # on Windows
dat - data.frame(age = factor(sample(1:4, 200, rep = T)), y =
runif(200))
head(dat) # ages are in random order
age y
1 3 0.64275524
2 1 0.56125314
3 2 0.82418228
4
Thank you! That was very helpful indeed!
Karen Subject: RE: [R] extracting a percentage of data by random Date: Thu, 6
Mar 2008 11:20:16 +1000 From: [EMAIL PROTECTED] To: [EMAIL PROTECTED];
r-help@r-project.org You don't need any explicit loops at all. Here is a
demo of one way to do it:
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