On Mon, Oct 20, 2008 at 4:10 PM, <[EMAIL PROTECTED]> wrote: > > 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$myvar <- 12, NA)))))))))))) > > Suggestions?
How about the following? x<-c(1,0,0,1,0,0,1,0,0,1) y<-c(1,3,2,3,2,1,2,3,2,3) z<-c(1,2,1,2,1,2,1,2,1,2) d<-as.data.frame(cbind(x,y,z)) xyz.comb<-interaction(x,y,z,lex.order=T) d$myvar<-match(xyz.comb,levels(xyz.comb)) /Gustaf Gustaf Rydevik, M.Sci. tel: +46(0)703 051 451 address:Essingetorget 40,112 66 Stockholm, SE skype:gustaf_rydevik ______________________________________________ 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.