I've got a data frame describing comments on an electronic journal, wherein each row is a unique comment, like so: commentID author articleID 1 1 smith 2 2 2 jones 3 3 3 andrews 2 4 4 jones 1 5 5 johnson 3 6 6 smith 2 I want know the number of unique authors per article. I can get a table of article frequencies with table(articleID), but I can't figure out how to count frequencies in a different column. I'm sure there's an easy way, but I guess I'm too new at this to find it. Thanks for your help! Jason Priem PhD student, School of Information and Library Science, University of North Carolina-Chapel Hill
Hi Jason, As your example is not reproducible, may be something like: myFreq<-data.frame(table(articleID, author)) if you want to know only those articles with 1 author, you can try subset(myFreq, Freq==1) or something like. bests milton On Sun, Nov 1, 2009 at 2:20 AM, Jason Priem <priem@email.unc.edu> wrote:> I've got a data frame describing comments on an electronic journal, wherein > each row is a unique comment, like so: > > commentID author articleID > 1 1 smith 2 > 2 2 jones 3 > 3 3 andrews 2 > 4 4 jones 1 > 5 5 johnson 3 > 6 6 smith 2 > > I want know the number of unique authors per article. I can get a table of > article frequencies with table(articleID), but I can't figure out how to > count frequencies in a different column. I'm sure there's an easy way, but > I guess I'm too new at this to find it. Thanks for your help! > > Jason Priem > PhD student, School of Information and Library Science, University of North > Carolina-Chapel Hill > > ______________________________________________ > 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<http://www.r-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. >[[alternative HTML version deleted]]
On Sun, 01-Nov-2009 at 01:20AM -0500, Jason Priem wrote:> I've got a data frame describing comments on an electronic journal, > wherein each row is a unique comment, like so: > > commentID author articleID > 1 1 smith 2 > 2 2 jones 3 > 3 3 andrews 2 > 4 4 jones 1 > 5 5 johnson 3 > 6 6 smith 2Let's call that dataframe x> > I want know the number of unique authors per article. I can get a table > of article frequencies with table(articleID), but I can't figure out how > to count frequencies in a different column. I'm sure there's an easy > way, but I guess I'm too new at this to find it.I'm not clear what you require, but maybe it's this:> with(x, table(articleID, author))articleID andrews johnson jones smith 1 0 0 1 0 2 1 0 0 2 3 0 1 1 0 Is that anything like what you're after? -- ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~. ___ Patrick Connolly {~._.~} Great minds discuss ideas _( Y )_ Average minds discuss events (:_~*~_:) Small minds discuss people (_)-(_) ..... Eleanor Roosevelt ~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.~.
Hi Jason, If I understand correctly, you are looking for something along the lines of with(X, tapply(author, articleID, function(x) length(unique(x)))) # 1 2 3 # 1 2 2 with X your data frame. HTH, Jorge On Sun, Nov 1, 2009 at 1:20 AM, Jason Priem <> wrote:> I've got a data frame describing comments on an electronic journal, wherein > each row is a unique comment, like so: > > commentID author articleID > 1 1 smith 2 > 2 2 jones 3 > 3 3 andrews 2 > 4 4 jones 1 > 5 5 johnson 3 > 6 6 smith 2 > > I want know the number of unique authors per article. I can get a table of > article frequencies with table(articleID), but I can't figure out how to > count frequencies in a different column. I'm sure there's an easy way, but > I guess I'm too new at this to find it. Thanks for your help! > > Jason Priem > PhD student, School of Information and Library Science, University of North > Carolina-Chapel Hill > > ______________________________________________ > 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]]