I'm not sure if you mean to ignore row 6 while ignoring row 4 or not so here are two solutions (depending on what you meant)
dput(x) # dput is your friend structure(list(kind = c(1L, 1L, 1L, 1L, 2L, 2L), x = c(8L, 44L, 25L, 36L, 2L, 36L), y = c(9L, 3L, 7L, 20L, 14L, 20L)), .Names = c("kind", "x", "y"), class = "data.frame", row.names = c("1", "2", "3", "4", "5", "6")) ## If you want to get rid of duplicates for both cases -- not the prettiest but it works table(x[!(duplicated(x[,-1], fromLast = TRUE) | duplicated(x[,-1])),1]) ## If you only want to get rid of it for the kind==1 rows (assuming the data.frame is sorted by kind) table(x[!duplicated(x[,-1], fromLast = TRUE), 1]) It's usually good practice to say what the answer you expect is to avoid this sort of confusion. Michael On Fri, Feb 24, 2012 at 2:00 PM, psy106616 <psy106...@163.com> wrote: > I have one data frame, like below: > kind x y > 1 1 8 9 > 2 1 44 3 > 3 1 25 7 > 4 1 36 20 > 5 2 2 14 > 6 2 36 20 > > so, I want to find unique coordinates in kind 1 rather than kind 2, ex, row > 4 should be excluded, is that possible? > > -- > View this message in context: > http://r.789695.n4.nabble.com/find-difference-between-data-frames-tp4418328p4418328.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.