Re: [R] averaging pairs of columns in a dataframe

That's great, thanks! Jon Gabor Grothendieck wrote: > > 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 >

[R] averaging pairs of columns in a dataframe

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 t