Vectors

Description

vector produces a vector of the given length and mode.

as.vector, a generic, attempts to coerce its argument into a vector of mode mode (the default is to coerce to whichever mode is most convenient).

is.vector returns TRUE if x is a vector of the specified mode having no attributes other than names. It returns FALSE otherwise.

Usage

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

Arguments

Details

The atomic modes are "logical", "integer", "numeric", "complex", "character" and "raw".

If mode = "any", is.vector returns TRUE for modes logical, integer, real, complex, character, raw, list or expression. It returns 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.

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

is.vector is a primitive function.

Value

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 elements to NULL.

All attributes are removed from the answer if it is of an atomic mode.

Note

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").

modes of "symbol", "pairlist" and "expression" are allowed but have long been undocumented.

References

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.

Examples

df <- data.frame(x=1:3, y=5:7)
## Not run: ## Error:
  as.vector(data.frame(x=1:3, y=5:7), mode="numeric")

## End(Not run)

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


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

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