search for: tp23962874p23962874

...,'a','c'), beta = c(1,3,2), val = c(2,6,4)) mergedf <- merge(x=completedf, y=partdf, by=c('alpha','beta')) # it only kept the common rows nrow(mergedf) Thanks, Etienne -- View this message in context: http://www.nabble.com/Merge-data-frame-and-keep-unmatched-tp23962874p23962874.html Sent from the R help mailing list archive at Nabble.com.