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\name{integer}
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\alias{integer}
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\alias{as.integer}
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\alias{as.integer.default}
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\alias{is.integer}
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\title{Integer Vectors}
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\description{
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  Creates or tests for objects of type \code{"integer"}.
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}
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\usage{
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integer(length = 0)
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as.integer(x, \dots)
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is.integer(x)
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}
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\arguments{
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  \item{length}{desired length.}
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  \item{x}{object to be coerced or tested.}
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  \item{\dots}{further arguments passed to or from other methods.}
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}
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\value{
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  \code{integer} creates a integer vector of the specified length.
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  Each element of the vector is equal to \code{0}.
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  Integer vectors exist so that data can be passed to C or Fortran code
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  which expects them.
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  \code{as.integer} attempts to coerce its argument to be of integer
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  type. The answer will be \code{NA} unless the coercion succeeds.
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  Real values larger in modulus than the largest integer are coerced to
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  \code{NA} (unlike S which gives the most extreme integer of the same sign).
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  Non-integral numeric values are truncated towards zero (i.e.,
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  \code{as.integer(x)} equals \code{\link{trunc}(x)} there), and
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  imaginary parts of complex numbers are discarded (with a warning).
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  Like \code{\link{as.vector}} it strips attributes including names.
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  \code{is.integer} returns \code{TRUE} or \code{FALSE} depending on
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  whether its argument is of integer type or not.
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  \code{is.integer} is generic: you can write methods to handle
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  specific classes of objects, see \link{InternalMethods}.
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  Note that factors are true for \code{is.integer} but false for
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  \code{\link{is.numeric}}.
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}
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\references{
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  Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
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  \emph{The New S Language}.
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  Wadsworth \& Brooks/Cole.
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}
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\seealso{
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  \code{\link{round}} (and \code{ceiling} and \code{floor} on that help
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  page) to convert to integral values.
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}
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\examples{
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  ## as.integer() truncates:
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  x <- pi * c(-1:1,10)
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  as.integer(x)
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}
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\keyword{classes}