Как насчет функции cut
, например,
df = data.frame(Age=c(32,47,72),
Var2=c("John","Julia","Mike"),
Var3=c("Green","Stone","White"),
Var4=c("Married","Divorced","Divorced"),
Var5=c("6'1","5'4","5'8"))
df$age = cut(df$Age,breaks = seq(20,80,10),
labels=paste0(seq(20,70,10),"-",seq(30,80,10)-1))