Skip to content

These type predicates aim to make type testing in R more consistent. They are wrappers around base::typeof(), so operate at a level beneath S3/S4 etc.


is_list(x, n = NULL)

is_atomic(x, n = NULL)

is_vector(x, n = NULL)

is_integer(x, n = NULL)

is_double(x, n = NULL, finite = NULL)

is_complex(x, n = NULL, finite = NULL)

is_character(x, n = NULL)

is_logical(x, n = NULL)

is_raw(x, n = NULL)

is_bytes(x, n = NULL)




Object to be tested.


Expected length of a vector.


Whether all values of the vector are finite. The non-finite values are NA, Inf, -Inf and NaN. Setting this to something other than NULL can be expensive because the whole vector needs to be traversed and checked.


Compared to base R functions:

  • The predicates for vectors include the n argument for pattern-matching on the vector length.

  • Unlike is.atomic(), is_atomic() does not return TRUE for NULL.

  • Unlike is.vector(), is_vector() tests if an object is an atomic vector or a list. is.vector checks for the presence of attributes (other than name).