Hello, I am looking for a method to eliminate rows dupblicates in a backwards manner, for instance: I want to keep A B but not B A (see my data.frame test). Thanks Hermann
> test a u 1 A B 2 A C 3 B A 4 B F 5 C A 6 D W > dput (test) structure(list(a = structure(c(1L, 1L, 2L, 2L, 3L, 4L), .Label = c("A", "B", "C", "D"), class = "factor"), u = structure(c(2L, 3L, 1L, 4L, 1L, 5L), .Label = c("A", "B", "C", "F", "W"), class = "factor")), .Names = c("a", "u"), row.names = c(NA, -6L), class = "data.frame") [[alternative HTML version deleted]] ______________________________________________ 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.