Hi maybe you can change combination of your columns to factor
new <-factor(paste(x,y,z, sep="")) and then reorder this factor (see reorder) change it to numeric to get index index <- as.numeric(factor) and then choose from set of 144 data data[index] or use your index directly if you need just numbers from 1 to the final to get your myvar. Maybe you could also look to permutations function from gtools package Regards Petr [EMAIL PROTECTED] napsal dne 20.10.2008 16:10:26: > > I'm trying to create a new column in my data.frame where subjects are > categorized depending on values on four other columns. In any other case I > would just nest a few ifelse statements, however, in this case i have > 4*6*2*3=144 combinations and i get weird 'context overflow' errors. So I > wonder if there is a more efficient way of doing this. > > For illustrational purposes, let's say i have: > > x<-c(1,0,0,1,0,0,1,0,0,1) > y<-c(1,3,2,3,2,1,2,3,2,3) > z<-c(1,2,1,2,1,2,1,2,1,2) > d<-as.data.frame(cbind(x,y,z)) > > and i do: > > d$myvar <- ifelse(d$x == 0 & d$y==1 & d$z==1 , d$myvar <- 1, > ifelse(d$x == 0 & d$y==1 & d$z==2 , d$myvar <- 2, > ifelse(d$x == 0 & d$y==2 & d$z==1 , d$myvar <- 3, > ifelse(d$x == 0 & d$y==2 & d$z==2 , d$myvar <- 4, > ifelse(d$x == 0 & d$y==3 & d$z==1 , d$myvar <- 5, > ifelse(d$x == 0 & d$y==3 & d$z==2 , d$myvar <- 6, > ifelse(d$x == 1 & d$y==1 & d$z==1 , d$myvar <- 7, > ifelse(d$x == 1 & d$y==1 & d$z==2 , d$myvar <- 8, > ifelse(d$x == 1 & d$y==2 & d$z==1 , d$myvar <- 9, > ifelse(d$x == 1 & d$y==2 & d$z==2 , d$myvar <- 10, > ifelse(d$x == 1 & d$y==3 & d$z==1 , d$myvar <- 11, > ifelse(d$x == 1 & d$y==3 & d$z==2 , d$myvar <- 12, NA)))))))))))) > > Suggestions? > > ______________________________________________ > 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.