Online R Compiler

set.seed(100) x1<-sample(LETTERS[1:4],20,replace=TRUE) x2<-sample(LETTERS[1:4],20,replace=TRUE) x3<-sample(LETTERS[1:4],20,replace=TRUE) x4<-sample(LETTERS[1:4],20,replace=TRUE) df1<-data.frame(x1,x2,x3,x4) df1