| is.recursive {base} | R Documentation |
is.atomic returns TRUE if x is of an atomic type
(or NULL) and FALSE otherwise.
is.recursive returns TRUE if x has a recursive
(list-like) structure and FALSE otherwise.
is.atomic(x) is.recursive(x)
x |
object to be tested. |
is.atomic is true for the atomic types
("logical", "integer", "numeric",
"complex", "character" and "raw") and NULL.
Most types of objects are regarded as recursive. Exceptions are the atomic
types, NULL, symbols (as given by as.name),
S4 objects with slots, external pointers, and—rarely visible
from R—weak references and byte code, see typeof.
It is common to call the atomic types ‘atomic vectors’, but
note that is.vector imposes further restrictions: an
object can be atomic but not a vector (in that sense).
These are primitive functions.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
is.list,
is.language, etc,
and the demo("is.things").
require(stats) is.a.r <- function(x) c(is.atomic(x), is.recursive(x)) is.a.r(c(a = 1, b = 3)) # TRUE FALSE is.a.r(list()) # FALSE TRUE - a list is a list is.a.r(list(2)) # FALSE TRUE is.a.r(lm) # FALSE TRUE is.a.r(y ~ x) # FALSE TRUE is.a.r(expression(x+1)) # FALSE TRUE is.a.r(quote(exp)) # FALSE FALSE