Question

I have a dataframe x with the columns a & b. I want to have a new column c whichs value is a/b. I’ve been using

x = read.csv(<file>,header=TRUE)
f <- function(...){
x$c = x$a / x$b
}
x = apply(x,1,f)

This messes up the dataframe so I suppose this is totally wrong. How can I access the values of the row on which apply is called at a given moment?

Answer 1

You don’t need to use apply. These operations work perfectly fine on vectors.

x$c <- x$a / x$b

Will work just fine on it’s own.

For more info check out ?'/'.