[R] Running *slow*

R. Michael Weylandt michael.weylandt at gmail.com
Thu Oct 6 15:12:33 CEST 2011


?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.alt at 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 at 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.
>



More information about the R-help mailing list