NULL represents the null object in R: it is a reserved word.
NULL is often returned by expressions and functions whose value is undefined.
as.null ignores its argument and returns the value
TRUE if its argument is
NULL as.null(x, ...) is.null(x)
- an object to be tested or coerced.
NULL can be indexed (see Extract) in just about any syntactically legal way: whether is makes sense or not, the result is always
NULL. Objects with value
NULL can be changed by replacement operators and will be coerced to the type of the right-hand side.
NULL is also used as the empty pairlist.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
is.null is a primitive function.
Documentation reproduced from R 3.0.2. License: GPL-2.