Harold -
Two ways that come to mind:
1) do.call(rbind,lapply(split(tmp,tmp$index),function(x)x[1:5,]))
2) subset(tmp,unlist(tapply(foo,index,seq))<=5)
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spec...@stat.berkeley.edu
On Mon, 20 Sep 2010, Doran, Harold wrote:
Suppose I have a data frame, such as the one below:
tmp <- data.frame(index = gl(2,20), foo = rnorm(40))
And further assume it is sorted by index and then by the variable foo.
tmp <- tmp[order(tmp$index, tmp$foo) , ]
Now, I want to grab the first N rows of tmp for each index. In the end, what I
want is the data frame 'result'
tmp1 <- subset(tmp, index == 1)
tmp2 <- subset(tmp, index == 2)
tmp1 <- tmp1[1:5,]
tmp2 <- tmp2[1:5,]
result <- rbind(tmp1, tmp2)
Does anyone see a way to subset and subsequently bind without a loop?
Harold
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