?unique x <- matrix(c(1:6, 6:1),ncol=2)
x.temp <- x dim(x.temp) <- NULL unique(x.temp) Michael On Thu, Oct 6, 2011 at 8:37 AM, Thomas <chesney....@gmail.com> wrote: > Anyone got any hints on how to make this code more efficient? An early > version (which to be fair did more than this one is) ran for 330 hours and > produced no output. > > I have a two column table, Dat, with 12,000,000 rows and I want to produce a > lookup table, ltable, in a 1 dimensional matrix with one copy of each of the > values in Dat: > > for (i in 1:nrow(Dat)) > { > for (j in 1:2) > { > #If next value is already in ltable, do nothing > if (is.na(match(Dat[i,j], ltable))){ltable <- rbind(ltable,Dat[i,j])} > } > } > > but it takes forever to produce anything. > > Any advice gratefully received. > > Thomas > > ______________________________________________ > 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. > ______________________________________________ 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.