Your code for iy doesn't work as provided....I'll assume you meant this instead:
iy <- list(c(1, 2),c(1, 2), c(1, 2, 3, 4), c(2, 3, 5), c(4), c(5, 6, 7), c(7, 8, 9)) Then sapply(iy, function(x) sum(Y1[x])) Michael On Sat, Mar 10, 2012 at 5:01 PM, aldi <a...@dsgmail.wustl.edu> wrote: > Hi, > > I have a vector > Y1 <-c(8, 11, 7, 5, 6, 3, 6, 3, 3) > and an index > iy <-c(c(1, 2),c(1 2), c(1, 2, 3, 4), c(2, 3, 5), c(4), c(5, 6, 7), c(7, 8, > 9)) > > how can I produce the mean, or the sum of the elements specified in the > index iy from the vector Y1? > > expecting something like this for the sum: > Y2 > 19 19 31 24 5 15 12 > > I thought lapply function may perform this, but does not work: > Y2<-lapply(Y1[iy],sum) > > Any suggestion? > TIA, > > Aldi > > -- > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
