Compare a value to null. Why is this true?

Question

Why is

isTRUE(NULL != 2)
[1] FALSE

And how would I receive TRUE?

In my real case I have variables and I want to process something,

Answer 1

In order to answer the why part of your question:

Comparing NULL with other types will give you logical(0) (i.e., a logical vector of length zero). So,

isTRUE(NULL != 2)

actually is

isTRUE(logical(0))

which is FALSE.

In order to compare the values where you might have NULL values also, you could also do something like this (using short circuit logical operator):

a <- 2
b <- 2
!is.null(a) && !is.null(b) && a==b
#[1] TRUE

a <- 3
b <- 2
!is.null(a) && !is.null(b) && a==b
#[1] FALSE

a <- 2
b <- NULL
!is.null(a) && !is.null(b) && a==b
#[1] FALSE