you can have a look at the rollapply() function in the zoo package, e.g.,
x <- rbinom(100, 1, 0.5)
z <- zoo(x)
rollapply(z, 3, sum)
I hope it helps.
Best,
Dimitris
Chris Oldmeadow wrote:
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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--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
