Is an Object Atomic or Recursive?
x is of an atomic type
x has a recursive
(list-like) structure and
- object to be tested.
is.atomic is true for the atomic types
Most types of objects are regarded as recursive, except for the atomic
NULL and symbols (as given by
It is common to call the atomic types atomic vectors, but
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.
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 (nowadays)