[R] Two statement logical dealing with NAs

[Duncan Murdoch]

On 12-12-10 7:55 PM, Hans Thompson wrote:
> Hello.
>
> I have a two statement logical that if NA is returned for the second
> statement I want to rely on result of the first statement.  I still would
> like to use both when I can though.
>
> x <- c(1:5)
> y <- c(1,2,NA,4,5)
> x < 5 & x-y == 0
>
> How can I trick R to refer back to (x < 5) where it is NA on the third
> value?

Use is.na() to test for NA.  I think this does what you want:

x < 5 & (is.na(x-y == 0) | x-y == 0)

Duncan Murdoch