| numeric {base} | R Documentation |
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 numeric type
(either integer or real).
is.numeric returns TRUE if its argument is of type real
or type integer and FALSE otherwise.
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. |
is.numeric is generic: you can write methods to handle
specific classes of objects, see InternalMethods.
Note that factors are false for is.numeric but true for
is.integer.
R has no single precision data type. All real numbers are
stored in double precision format. While as.numeric is a
generic function, user methods must be written for as.double,
which it calls
as.numeric for factors yields the codes underlying the factor
levels, not the numeric representation of the labels.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
as.numeric(c("-.1"," 2.7 ","B")) # (-0.1, 2.7, NA) + warning
as.numeric(factor(5:10))