[R] combining elements in a data frame

Hi all, I have 2 data frames the first contains a list with repeats of words and an associated response time (RT) measure for each word. The second is a tabulation of each unique word and other information such as the amount and of responses for each word. I need to determine the mean RT

[R] matching items in a data frame

I have a data frame with 2 columns, the first is an index of participants and the second is a list of words presented to the participant (see below). > head(dat) sword 1a pianist 1a sweat 1a carnage 1a nymph 1ahank 1a waist > tail(dat) sword 4a package 4a