See ?apply. Example y <- rnorm(3000), dim(y) <- c(3, 1000) my <- apply(y, MARGIN=2, FUN=mean, na.rm=TRUE)
to calculate the mean over the 2nd index, that is, for each column, and pass argument na.rm=TRUE to each call to mean(). This is in practice the same as my <- rep(NA, ncol(y)) for (kk in 1:ncol(y)) my[kk] <- mean(y[,kk], na.rm=TRUE) but apply() is to prefer when you get used to it. Best wishes Henrik Bengtsson > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Thomas Hopper > Sent: Tuesday, January 11, 2005 4:46 AM > To: r-help@stat.math.ethz.ch > Subject: [R] Calculate Mean of Column Vectors? > > > Hello, > > I've got an array defined as y <- rnorm(3000), dim(y) <- c(3, 1000). > > I'd like to produce a 1000-element vector z that is the mean of the > corresponding elements of y (like z[1,1] <- mean(y[1,1], y[2,1], > y[3,1])), but being new to R, I'm not sure how to do this for all > elements at once (or, at least, simply). Any help is appreciated. > > Thanks, > > Tom > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html