Hi: Here are three solutions; since this question comes up fairly often, you can find other solutions in the R-help archives.
(1) Use functions from base R: split the data frame by ID, extract the first record from each split and slurp them together with rbind(): > do.call(rbind, lapply(split(df, df$ID), head, 1)) ID x 1 1 -0.7736769 2 2 -0.7906979 3 3 0.3889229 4 4 -1.2277544 5 5 0.2820819 (2) Use the plyr package and function ddply(): library(plyr) > ddply(df, .(ID), head, 1) ID x 1 1 -0.7736769 2 2 -0.7906979 3 3 0.3889229 4 4 -1.2277544 5 5 0.2820819 (3) A third solution using package doBy: library(doBy) > df[firstobs(~ ID, data = df), ] ID x 1 1 -0.7736769 2 2 -0.7906979 5 3 0.3889229 10 4 -1.2277544 12 5 0.2820819 HTH, Dennis On Mon, May 3, 2010 at 6:04 AM, someone <vonhof...@t-online.de> wrote: > > as a r noob i am having another problem: > i have a big dataframe where each row corresponds to one entry and each > column is a field... > for instance, i have the column ID and time and many more... > Id like to get a dataframe where all IDs are just included once (some users > with that ID might have several entries but Id like to kepp only one).. > when i use unique I only get a list of the levels (or different IDs) > could someone help me out and tell me how to get the dataframe with only > one > entry for each ID? > > -- > View this message in context: > http://r.789695.n4.nabble.com/Delete-rows-with-duplicate-field-tp2123939p2123939.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. > [[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.