On Aug 3, 2010, at 10:48 PM, Ralf B wrote:
Hi all,
I have a data frame with column over which I would like to run
repeated functions for data analysis. Currently I am only running
recursively over two columns where I column 1 has two states over
which I split and column two has 3 states. The function therefore runs
2 x 3 = 6 times as shown when running the following code:
mydata <- data.frame(userid = c(5, 6, 5, 6, 5, 6), taskid = c(1, 1,
2, 2, 3, 3),
stuff = 11:16)
mydata
mydata <- mydata[with(mydata, order(userid, taskid)), ]
mydata
lapply(split(mydata, mydata[,1]), function(x){
lapply(split(x, x[,2]), function(y){
print(paste("result:",y))
})
})
This traverses the tree like this:
5,1
5,2
5,3
6,1
6,2
6,3
Is there an easier way of doing that? I would like to provide the two
columns (index 1 and index 2) directly and have the ?lapply function
perform its lambda function directly on each memebr of the tree
automatically? How can I do that?
split(mydata, with(mydata, paste(userid, taskid, sep=".")))
Perhaps something like:
lapply( split(mydata, with(mydata, paste(userid, taskid, sep="."))),
function(x) paste("result:", x))
David Winsemius, MD
West Hartford, CT
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