is.language(x)
is.language
returns TRUE
if x
is either a
variable name
, a call
, or an
expression
.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) sapply(ll, is.language)# all TRUE