Try this where DF is your data frame: subset(DF, !duplicated(ID))
or equivalently: DF[!duplicated(DF$ID), ] On Sat, Jan 16, 2010 at 5:04 PM, Bryan M Hangartner <[email protected]> wrote: > To Whomever is Interested, > > I have spent several days searching the web, help files, the R wiki and the > archives of this mailing list for a solution to this problem, but > nonetheless I apologize in advance if I have missed something obvious. > > The problem is this; I have a 5-column data frame with about 4.2 million > rows, and want to create a new (and hopefully much smaller) data frame that > contains only the rows which have a unique value in the first column only. > In other words, I do not care about the uniqueness of the values in the > other four rows, only the uniqueness of the entries in the first row. The > "unique" command does not seem to have this option available, at least based > on what I've read in the help file. > > A simplified example matrix (designated as "traveltimes"): > > ID Time1 Time2 > 1 3 4 > 1 4 7 > 2 3 5 > 2 5 6 > 3 4 5 > 3 2 8 > > When I use a command such as > > matches <- unique(traveltimes, incomparables = FALSE, fromLast = FALSE) > > I will end up with a 6-row matrix, exactly what I already have. What I would > like to do is to remove the duplicate values in the column labeled "ID" and > their associated Time1 and Time2 entries. This will give me a 3x3 matrix > which contains only one instance of each "ID" variable. For the purposes of > this particular problem, the uniqueness of the Time1 and Time2 rows is not > relevant. > > If this question is not clear enough please let me know. Thank you for your > time. > > > -- > Bryan Hangartner > [email protected] > > ______________________________________________ > [email protected] 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. > ______________________________________________ [email protected] 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.
