Thanks, Bill. match() is nice and efficient. However, I met a problem: My real data is a large _list_ named "read.genes". I found conflict results between match() and unique() - the lengths of the outcomes are different (and my final result are wrong too). I suspect that some different list components are regarded as the same when they are converted to vectors (the r-help of match() says "Factors, raw vectors and lists are converted to character vectors"). Is it possible? And as important, how to fix this?
> read.genes[[1]] [1] "YAL065C" "YAL063C" "YAR050W" "YHR211W" > duplicates <- as.vector(table(match(read.genes, read.genes))) > length(duplicates) [1] 1424 > read.genes.uniq <- unique(read.genes) > length(read.genes.uniq) [1] 1469 > sum(duplicates) [1] 9945348 > length(read.genes) [1] 9945348 On Wed, Aug 31, 2011 at 12:42 PM, William Dunlap <wdun...@tibco.com> wrote: > table(match(x, x)) gives you the numbers but the labels are > a bit more work. > > E.g., I'll define another list > > x <- list(c("1", "2", "4"), c("1", "2", "4"), 2^(0:4), 3^(1:2), 2^(0:4)) > > tb <- table(m <- match(x, x)) > > m > [1] 1 1 3 4 3 > > tb > > 1 3 4 > 2 2 1 > which says that the first element of x is seen twice, > the third twice, and the fourth once. How to organize > that the best depends on what you want to do with the > data. > > Bill Dunlap > Spotfire, TIBCO Software > wdunlap tibco.com > > > -----Original Message----- > > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] > On Behalf Of zhenjiang xu > > Sent: Wednesday, August 31, 2011 9:25 AM > > To: r-help > > Subject: [R] counting the duplicates in an object of list > > > > Hi all, > > > > I have a list x: > > > > > x=list(a=c('1','2'),b=c('2','3'),c=c('1','2'),d=c('2','3')) > > > > I can get the unique elements with unique(), but how can I get the > > number of duplicates for each unique elements? > > > > > unique(x) > > [[1]] > > [1] "1" "2" > > > > [[2]] > > [1] "2" "3" > > > > Thanks > > > > -- > > Best, > > Zhenjiang > > > > ______________________________________________ > > 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. > -- Best, Zhenjiang [[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.