What about something like this: tmp <- data.frame(var1 = rnorm(36), ind = gl(6,6))
with(tmp, tapply(var1, ind, mean)) You can see that your version of mean(tmp[1:6,c("var1")]) gives the same as mine for the first 6 rows. -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of jsf1982 Sent: Tuesday, August 13, 2013 12:46 PM To: r-help@r-project.org Subject: [R] Regular repeats Hi, Many apologies for the simplicity (hopefully!) of this request - I can't find it on the forum, but it may have been asked in the past. I have a data frame consisting of ~2000 rows. I simply want to take the average of the first 6, then the next 6, then the next 6 until the end of the table. The command mean(mole[1:6,c("PercentPI")]) gets me the first 6 rows (column is PercentPI), but I don't know how to increase the rows incrementally. Thanks in advance. J -- View this message in context: http://r.789695.n4.nabble.com/Regular-repeats-tp4673653.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. ______________________________________________ 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.