This was asked before. Collapse the data frame into a vector, e.g. v <- apply(DF,1,function(x) {paste(x,collapse="_")}) then work with the values of that vector (table, unique etc). If your data frame is really large run this in a DBMS.
> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Federico Calboli > Sent: Monday, October 30, 2006 11:35 AM > To: r-help > Subject: [R] memory management > > Hi All, > > just a quick (?) question while I wait my code runs... > > I'm comparing the identity of the lines of a dataframe, doing > all possible > pairwise comparisons. In doing so I use identical(), but > that's by the way. I'm > doing a (not so) quick and dirty check, and subsetting the data as > > data[row.numb,] > > and > > data[a different row,] > > I suspect the problem there is that I load into memory the > whole frame data[,] > every time, making the biz quite slow and wasteful. As I'm > idly waiting, I > though, had I put every line of data[,] as the item of a > list, then done my > pairwise comparisons using the list, would I have had a > better performance? > > (do I win the prize for the most convoluted sentence sent to > the R-help?) > > For the pedants, yes, I know I could kill the process and try > myself, but the > spirit of the question is, is there a way of dealing with big > data *efficiently*? > > Best, > > Fede > > -- > Federico C. F. Calboli > Department of Epidemiology and Public Health > Imperial College, St Mary's Campus > Norfolk Place, London W2 1PG > > Tel +44 (0)20 7594 1602 Fax (+44) 020 7594 3193 > > f.calboli [.a.t] imperial.ac.uk > f.calboli [.a.t] gmail.com > > ______________________________________________ > R-help@stat.math.ethz.ch 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@stat.math.ethz.ch 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.