vector {base}R Documentation

Vectors - Creation, Coercion, etc


A vector in R is either an atomic vector i.e., one of the atomic types, see ‘Details’, or of type (typeof) or mode list or expression.

vector produces a ‘simple’ vector of the given length and mode, where a ‘simple’ vector has no attribute, i.e., fulfills is.null(attributes(.)).

as.vector, a generic, attempts to coerce its argument into a vector of mode mode (the default is to coerce to whichever vector mode is most convenient): if the result is atomic (is.atomic), all attributes are removed. For mode="any", see ‘Details’.

is.vector(x) returns TRUE if x is a vector of the specified mode having no attributes other than names. For mode="any", see ‘Details’.


vector(mode = "logical", length = 0)
as.vector(x, mode = "any")
is.vector(x, mode = "any")



character string naming an atomic mode or "list" or "expression" or (except for vector) "any". Currently, is.vector() allows any type (see typeof) for mode, and when mode is not "any", is.vector(x, mode) is almost the same as typeof(x) == mode.


a non-negative integer specifying the desired length. For a long vector, i.e., length > .Machine$integer.max, it has to be of type "double". Supplying an argument of length other than one is an error.


an R object.


The atomic modes are "logical", "integer", "numeric" (synonym "double"), "complex", "character" and "raw".

If mode = "any", is.vector may return TRUE for the atomic modes, list and expression. For any mode, it will return FALSE if x has any attributes except names. (This is incompatible with S.) On the other hand, as.vector removes all attributes including names for results of atomic mode.

For mode = "any", and atomic vectors x, as.vector(x) strips all attributes (including names), returning a simple atomic vector.
However, when x is of type "list" or "expression", as.vector(x) currently returns the argument x unchanged, unless there is an as.vector method for class(x).

Note that factors are not vectors; is.vector returns FALSE and as.vector converts a factor to a character vector for mode = "any".


For vector, a vector of the given length and mode. Logical vector elements are initialized to FALSE, numeric vector elements to 0, character vector elements to "", raw vector elements to nul bytes and list/expression elements to NULL.

For as.vector, a vector (atomic or of type list or expression). All attributes are removed from the result if it is of an atomic mode, but not in general for a list or expression result. The default method handles 24 input types and 12 values of type: the details of most coercions are undocumented and subject to change.

For is.vector, TRUE or FALSE. is.vector(x, mode = "numeric") can be true for vectors of types "integer" or "double" whereas is.vector(x, mode = "double") can only be true for those of type "double".

Methods for as.vector()

Writers of methods for as.vector need to take care to follow the conventions of the default method. In particular


as.vector and is.vector are quite distinct from the meaning of the formal class "vector" in the methods package, and hence as(x, "vector") and is(x, "vector").

Note that as.vector(x) is not necessarily a null operation if is.vector(x) is true: any names will be removed from an atomic vector.

Non-vector modes "symbol" (synonym "name") and "pairlist" are accepted but have long been undocumented: they are used to implement and as.pairlist, and those functions should preferably be used directly. None of the description here applies to those modes: see the help for the preferred forms.


Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

c, is.numeric, is.list, etc.


df <- data.frame(x = 1:3, y = 5:7)
## Error:
try(as.vector(data.frame(x = 1:3, y = 5:7), mode = "numeric"))

x <- c(a = 1, b = 2)
all.equal(x, as.vector(x)) ## FALSE

###-- All the following are TRUE:
! is.vector(df)
! is.vector(df, mode = "list")

is.vector(list(), mode = "list")

[Package base version 4.4.1 Index]