| NULL {base} | R Documentation |
NULL represents the null object in R.
NULL is used mainly to represent the lists with zero length,
and is often returned by expressions and functions whose
value is undefined.
as.null ignores its argument and returns the value NULL.
is.null returns TRUE if its argument
is NULL and FALSE otherwise.
NULL as.null(x, ...) is.null(x)
x |
an object to be tested or coerced. |
... |
ignored. |
is.null is generic: you can write methods to handle
specific classes of objects, see InternalMethods.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
is.null(list()) # FALSE (on purpose!) is.null(integer(0))# F is.null(logical(0))# F as.null(list(a=1,b='c'))