Creates or coerces objects of type
is.numeric is a more general test of an object being interpretable as numbers.
numeric(length = 0) as.numeric(x, ...) is.numeric(x)
- A non-negative integer specifying the desired length. Double values will be coerced to integer: supplying an argument of length other than one is an error.
- object to be coerced or tested.
- further arguments passed to or from other methods.
is.numeric is an internal generic
primitive function: you can write methods to handle specific classes of objects, see InternalMethods. It is not the same as
is.double. Factors are handled by the default method, and there are methods for classes
"difftime" (all of which return false). Methods for
is.numeric should only return true if the base type of the class is
integer and values can reasonably be regarded as numeric (e.g. arithmetic on them makes sense, and comparison should be done via the base type).
The default method for
TRUE if its argument is of mode
"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).
Note on names
The potential confusion is that R has used mode
"numeric" to mean ‘double or integer’, which conflicts with the S4 usage. Thus
is.numeric tests the mode, not the class, but
as.numeric (which is identical to
as.double) coerces to the class.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
Documentation reproduced from R 3.0.1. License: GPL-2.