How to test if object is a vector

Question

How to test if an object is a vector, i.e. mode logical, numeric, complex or character? The problem with is.vector is that it also returns TRUE for lists and perhaps other types:

> is.vector(list()) [1] TRUE 

I want to know if it is a vector of primitive types. Is there a native method for this, or do I have to go by storage mode?

Answer 1

There are only primitive functions, so I assume you want to know if the vector is one of the atomic types. If you want to know if an object is atomic, use is.atomic.

is.atomic(logical()) is.atomic(integer()) is.atomic(numeric()) is.atomic(complex()) is.atomic(character()) is.atomic(raw()) is.atomic(NULL) is.atomic(list())        # is.vector==TRUE is.atomic(expression())  # is.vector==TRUE is.atomic(pairlist())    # potential "gotcha": pairlist() returns NULL is.atomic(pairlist(1))   # is.vector==FALSE 

If you're only interested in the subset of the atomic types that you mention, it would be better to test for them explicitly:

mode(foo) %in% c("logical","numeric","complex","character") 

Answer 2

Perhaps not the optimal, but it will do the work: check if the variable is a vector AND if it's not a list. Then you'll bypass the is.vector result:

if(is.vector(someVector) & !is.list(someVector)) {    do something with the vector  }