[R] sliding window over a large vector
Chris Oldmeadow
c.oldmeadow at student.qut.edu.au
Tue Dec 16 05:19:55 CET 2008
Hi all,
I have a very large binary vector, I wish to calculate the number of
1's over sliding windows.
this is my very slow function
slide<-function(seq,window){
n<-length(seq)-window
tot<-c()
tot[1]<-sum(seq[1:window])
for (i in 2:n) {
tot[i]<- tot[i-1]-seq[i-1]+seq[i]
}
return(tot)
}
this works well for for reasonably sized vectors. Does anybody know a
way for large vectors ( length=12 million), im trying to avoid using C.
Thanks,
Chris
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