[R] is.na()<- on a character vector

[Göran Broström]

I'm confused:

> x <- 1:2
> is.na(x) <- 1
> x
[1] NA  2

OK, but

> x <- c("A", "B")
> is.na(x) <- "A"
> x
               A 
"A" "B"  NA  

What happens?

G_ran