Try this: # test data DF <- data.frame(a = 1:9, a = 21:29, b = 31:39, b = 41:49, check.names = FALSE)
t(apply(DF, 1, tapply, names(DF), mean)) It gives a matrix so use as.data.frame on that if you need a data frame On Wed, Aug 27, 2008 at 9:47 AM, JonD <[EMAIL PROTECTED]> wrote: > > Dear all, > > I have a dataframe with 132 columns and 100 rows. Every 2nd column is a > repeat measurement so that the columns could be titled, a a b b c c d d etc. > I would like to average the repeats such that I am left with a data frame of > 66 columns (of means) and 100 rows. > > I have been trying to use rowMeans but have not been able to average the > pairs of columns, only the whole dataframe. > > Any help would be appreciated, I am new to R. > > Thanks in advance, > > Jon. > -- > View this message in context: > http://www.nabble.com/averaging-pairs-of-columns-in-a-dataframe-tp19181319p19181319.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.
