Ha Guillaume,
Is this what you are looking for?
#---------------
x1<-sample(1:10,5,replace=FALSE)
x2<-sample(1:10,100,replace=TRUE)
#This
tapply(x1,1:5,FUN=function(i){which(x2==i)})
#or this
tapply(x1,x1,FUN=function(i){which(x2==i)})
#---------------
Gerrit
______________________________________________
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.
