This overwrites the data so you might want to create a copy first. example <- data.frame(V1=c(3, -1), V2=c(-2, 4), V3=c(4, 1)) tf <- ifelse(example<0, TRUE, FALSE) example[tf] <- NA apply(example, 1, mean, na.rm=TRUE)
---------------------------------------------- David L Carlson Associate Professor of Anthropology Texas A&M University College Station, TX 77843-4352 > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Andrea Sica > Sent: Monday, May 14, 2012 11:32 AM > To: r-help@r-project.org > Subject: [R] select data > > Dear all, > > I am sure it won't be difficult for you!! > I need to calculate the average among variables for the single units of > my > dataset. > But, while doing it, I need to do not consider some values. > To better explain, think like there are two units and three variables: > > V1 V2 V3 > [1] 3 -2 4 > [2] -1 4 1 > > and you want to calculate the average by row, without considering those > negative values: > > => mean(1row) = (3+4)/2 > => mean(2row) = (4+1)/2 > > Could anyone please give me the commands to do that in R? > > Thank you so much > > [[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. ______________________________________________ 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.
