On Thu, 4 Dec 2003, Jan Wantia wrote: > Dear all! > > After hours of trying around, I gave up: > > I have a 2-dimensional array, and I know how to split it into its rows > and how to get the mean for every row using 'sapply'. > But what I want is to calculate the mean over the first n rows, and then > the second n rows, etc., so that I get a vector like: > > v == mean1(row 1:5), mean2(row6:10),... > > (trivial, you might say. I find it rather mind-boggling, though: I tried > to get the mean from the array before splitting it, after splitting it, > looping through it with for-loops...I feel like an idiot by now; looks > like I missed a crucial point of how 'R' works.) >
There is also a function rowsum() for doing precisely this (it's quite a bit faster than the tapply solution). -thomas ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help