Integer Vectors

Description

Creates or tests for objects of type "integer".

Usage

integer(length = 0)
as.integer(x, ...)
is.integer(x)

Arguments

Details

Integer vectors exist so that data can be passed to C or Fortran code which expects them, and so that small integer data can be represented exactly and compactly.

Note that on almost all implementations of R the range of representable integers is restricted to about +/-2*10^9: doubles can hold much larger integers exactly.

Value

integer creates a integer vector of the specified length. Each element of the vector is equal to 0.
as.integer attempts to coerce its argument to be of integer type. The answer will be NA unless the coercion succeeds. Real values larger in modulus than the largest integer are coerced to NA (unlike S which gives the most extreme integer of the same sign). Non-integral numeric values are truncated towards zero (i.e., as.integer(x) equals trunc(x) there), and imaginary parts of complex numbers are discarded (with a warning). Character strings containing either a decimal representation or a heaxadecimal representation (starting with 0x or 0X) can be converted, as well as any allowed by the platform for real numbers. Like as.vector it strips attributes including names.
is.integer returns TRUE or FALSE depending on whether its argument is of integer type or not. is.integer is generic: you can write methods to handle specific classes of objects, see InternalMethods. There is a method for factors which returns FALSE. (Prior to R 2.0.0, there was no such method and for most (but not all) factors is.integer returned TRUE.)

References

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

See Also

round (and ceiling and floor on that help page) to convert to integral values.

Examples

  ## as.integer() truncates:
  x <- pi * c(-1:1,10)
  as.integer(x)