is.language {base} | R Documentation |
is.language
returns TRUE
if x
is either a
variable name
, a call
, or an
expression
.
is.language(x)
x |
object to be tested. |
is.language
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.
ll <- list(a = expression(x^2 - 2*x + 1), b = as.name("Jim"), c = as.expression(exp(1)), d = call("sin", pi)) sapply(ll, typeof) sapply(ll, mode) stopifnot(sapply(ll, is.language))