| numeric {base} | R Documentation |
Creates or tests for objects of type "numeric".
numeric(length = 0) as.numeric(x, ...) is.numeric(x)
length |
desired length. |
x |
object to be coerced or tested. |
... |
further arguments passed to or from other methods. |
as.numeric is a generic function, but methods must be
written for as.double, which it calls.
is.numeric is generic: you can write methods to handle
specific classes of objects, see InternalMethods.
numeric creates a real vector of the specified length. The
elements of the vector are all equal to 0.
as.numeric attempts to coerce its argument to "double"
(even if it is already "integer").
as.numeric for factors yields the codes underlying the factor
levels, not the numeric representation of the labels, see also
factor.
The default method for is.numeric returns TRUE
if its argument is of mode "numeric"
(type "double" or type "integer") and not a
factor, and FALSE otherwise. That is,
is.integer(x) || is.double(x), or
(mode(x) == "numeric") && !is.factor(x).
R has no single precision data type. All real numbers are stored in double precision format.
numeric and as.numeric are the identical to double and
as.double (unless someone defines S4 methods on one of them).
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
double, integer, storage.mode.
as.numeric(c("-.1"," 2.7 ","B")) # (-0.1, 2.7, NA) + warning
as.numeric(factor(5:10))