Try this: merge(my.df, my.lookup)
On Mon, Nov 8, 2010 at 5:43 PM, Dimitri Liakhovitski < dimitri.liakhovit...@gmail.com> wrote: > Hello! > Hope there is a nifty way to speed up my code by avoiding loops. > My task is simple - analogous to the vlookup formula in Excel. Here is > how I programmed it: > > # My example data frame: > set.seed(1245) > > my.df<-data.frame(names=rep(letters[1:3],3),value=round(rnorm(9,mean=20,sd=5),0)) > my.df<-my.df[order(my.df$names),] > my.df$names<-as.character(my.df$names) > (my.df) > > # My example lookup table: > my.lookup<-data.frame(names=letters[1:3],category=c("AAA","BBB","CCC")) > my.lookup$names<-as.character(my.lookup$names) > my.lookup$category<-as.character(my.lookup$category) > (my.lookup) > > # Just adding an extra column to my.df that contains the categories of > the names in the column "names": > my.df2<-my.df > my.df2$category<-NA > for(i in unique(my.df$names)){ > my.df2$category[my.df2$names %in% > i]<-my.lookup$category[my.lookup$names %in% i] > } > (my.df2) > > It does what I need, but it's way too slow - I need to run it for > hundreds and hundreds of names in >100 of huge files (tens of > thousands of rows in each). > Any way to speed it up? > > > Thanks a lot! > > -- > Dimitri Liakhovitski > Ninah Consulting > www.ninah.com > > ______________________________________________ > 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. > -- Henrique Dallazuanna Curitiba-Paraná-Brasil 25° 25' 40" S 49° 16' 22" O [[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.