Hi rcoder, Assuming that the number of rows of your matrix x is even, try also:
x <- matrix(1:72,12) apply(x,2, tapply, rep(1:(nrow(x)/2),each=2),prod) # or using a function which argument "x" is your matrix prod.mat=function(x) { k=nrow(x) g=rep(1:(k/2),each=2) apply(x,2, tapply, g,prod) } prod.mat(x) HTH, Jorge On Sun, Jul 27, 2008 at 6:20 PM, rcoder <[EMAIL PROTECTED]> wrote: > > Hi everyone, > > I want to perform an operation on a matrx that outputs the product of > successive pairs of rows. For example: calculating the product between rows > 1 & 2; 3 & 4; 5 & 6...etc. > > Does anyone know of any readily available functions that can do this? > > Thanks, > > rcoder > > > -- > View this message in context: > http://www.nabble.com/product-of-successive-rows-tp18681259p18681259.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.