try this: > mydata <- matrix(runif(5000),ncol=5) > indices <- list(c(173, 193), + c(434, 455), + c(699, 724), + c(955, 977)) > result <- lapply(indices, function(.indx){ + mean(mydata[.indx[1]:.indx[2], 5]) + }) > > > result [[1]] [1] 0.5364535 [[2]] [1] 0.4080824 [[3]] [1] 0.5109079 [[4]] [1] 0.4392921 >
On Sun, Dec 27, 2009 at 9:14 AM, Edouard Tallent <tallen...@lycos.com>wrote: > I have a 5-row matrix called data. There are headers. > it look like this : > Row 1 Row2 Row3 Row4 Row5 > Line1 > Line2 > Line3 > > Line 1838 > I want to calculate several simple arithmetic means for Row5, that is from > Line173 to Line193, from Line434 to Line455, from Line699 to Line724, from > Line955 to Line977 > A simple way is to individually compute these means. The first one > (Line173 to Line193) is then obtained by : > >mean(data[173:193,5], na.rm = TRUE) > Thats right ! But, I aim to automate this calculation by creating a loop. > I tried many things, but I have been unsuccessful at using the for loop > function. > Please, dont explain things too hard as it is often the case that people > wants to help but gets into too much sophistication. > Someone can write that little code for this example ? Or suggest functions > ? > Thanks for your help. > Cheers, > Édouard. > > [[alternative(swapped) HTML version deleted]] > > This is MIME Epilogue > > > ______________________________________________ > 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<http://www.r-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. > > -- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve? [[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.