Question

I came to R from SAS, where numeric missing is set to infinity. So we can just say:

positiveA = A > 0;

In R, I have to be verbose like:

positiveA <- ifelse(is.na(A),0, ifelse(A > 0, 1, 0))

I find this syntax is hard to read. Is there anyway I can modify ifelse function to consider NA a special value that is always false for all comparison conditions? If not, considering NA as -Inf will work too.

Similarly, setting NA to ” (blank) in ifelse statement for character variables.

Thanks.

Answer 1

This syntax is easier to read:

x <- c(NA, 1, 0, -1)

(x > 0) & (!is.na(x)) 
# [1] FALSE  TRUE FALSE FALSE

(The outer parentheses aren’t necessary, but will make the statement easier to read for almost anyone other than the machine.)

---

Edit:

## If you want 0s and 1s
((x > 0) & (!is.na(x))) * 1
# [1] 0 1 0 0

Finally, you can make the whole thing into a function:

isPos <- function(x) {
    (x > 0) & (!is.na(x)) * 1
}

isPos(x)
# [1] 0 1 0 0