NULL {base}

R Documentation

The Null Object

Description

NULL represents the null object in R: it is a reserved word. NULL is often returned by expressions and functions whose value is undefined: it is also used as the empty pairlist.

as.null ignores its argument and returns the value NULL.

is.null returns TRUE if its argument is NULL and FALSE otherwise.

Usage

NULL
as.null(x, ...)
is.null(x)

Arguments

x	an object to be tested or coerced.
...	ignored.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

Examples

is.null(list())    # FALSE (on purpose!)
is.null(integer(0))# F
is.null(logical(0))# F
as.null(list(a=1,b='c'))

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