[R] How to preserve NULL in vector

[Daren Tan]

I have a vector containing NULL. Referencing to that NULL gives me NA
instead, which disrupt my codes. How can i preserve NULL as it is ?

> res <- c(1,2,NULL)
> res[1]
[1] 1
> res[2]
[1] 2
> res[3]
[1] NA