Hi megh, Perhaps? # Data x = vector("list") for (i in 1:5) x[[i]] = rnorm(2)
# 2x2 matrices res <- lapply(x, function(a) a %*% t(a) ) res # Funcion from ?Reduce add <- function(x) Reduce("+", x) # Summing up! add(res) See ?lapply and ?Reduce for more information. HTH, Jorge On Wed, Jul 22, 2009 at 3:18 PM, megh <megh700...@yahoo.com> wrote: > > Hi, > I have created a list object like that : > x = vector("list") > for (i in 1:5) x[[i]] = rnorm(2) > x > > Now I want to do two things : > 1. for each i, I want to do following matrix calculation : t(x[[i]]) %*% > x[[i]] i.e. for each i, I want to get a 2x2 matrix > 2. Next I want to get x[[1]] + x[[2]] +.... > > I did following : res=vector("list"); res = sapply(x, function(i) t(x[[i]]) > %*% x[[i]]) > However above syntax is not giving desired result. Any suggestion please? > > -- > View this message in context: > http://www.nabble.com/A-question-on-operation-on-list-tp24612796p24612796.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > [[alternative HTML version deleted]] ______________________________________________ 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.