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

You don't need a loop. You have nearly all you need:

test[test$a > 15 & test$a < 20, "e"] <- 2