refactor data.frame column values

Question

Sorry guys if this is a noob question. I need help on how to loop over my dataframe.Here is a sample data.

a <- c(10:29);
b <- c(40:59);
e <- rep(1,         


        

Answer 1

data.frame(a, b, e=(1:4)[cut(a, c(-Inf, 15, 20, 25, 30))])

Update:

Greg's comment provides a more direct solution without the need to go via subsetting an integer vector with a factor returned from cut.

data.frame(a, b, e=findInterval(a, c(-Inf, 15, 20, 25, 30)))