| % File src/library/base/man/logical.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2011 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{logical} |
| \alias{logical} |
| \alias{as.logical} |
| \alias{as.logical.factor} |
| \alias{is.logical} |
| \alias{TRUE} |
| \alias{FALSE} |
| \alias{T} |
| \alias{F} |
| \title{Logical Vectors} |
| \description{ |
| Create or test for objects of type \code{"logical"}, and the basic |
| logical constants. |
| } |
| \usage{ |
| TRUE |
| FALSE |
| T; F |
| |
| logical(length = 0) |
| as.logical(x, \dots) |
| is.logical(x) |
| } |
| \details{ |
| \code{TRUE} and \code{FALSE} are \link{reserved} words denoting logical |
| constants in the \R language, whereas \code{T} and \code{F} are global |
| variables whose initial values set to these. All four are |
| \code{logical(1)} vectors. |
| |
| Logical vectors are coerced to integer vectors in contexts where a |
| numerical value is required, with \code{TRUE} being mapped to |
| \code{1L}, \code{FALSE} to \code{0L} and \code{NA} to \code{NA_integer_}. |
| } |
| \arguments{ |
| \item{length}{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.} |
| \item{x}{object to be coerced or tested.} |
| \item{\dots}{further arguments passed to or from other methods.} |
| } |
| \value{ |
| \code{logical} creates a logical vector of the specified length. |
| Each element of the vector is equal to \code{FALSE}. |
| |
| \code{as.logical} attempts to coerce its argument to be of logical |
| type. For \code{\link{factor}}s, this uses the \code{\link{levels}} |
| (labels). Like \code{\link{as.vector}} it strips attributes including |
| names. Character strings \code{c("T", "TRUE", "True", "true")} are |
| regarded as true, \code{c("F", "FALSE", "False", "false")} as false, |
| and all others as \code{NA}. |
| |
| \code{is.logical} returns \code{TRUE} or \code{FALSE} depending on |
| whether its argument is of logical type or not. |
| } |
| \seealso{ |
| \code{\link{NA}}, the other logical constant. |
| } |
| \references{ |
| Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) |
| \emph{The New S Language}. |
| Wadsworth & Brooks/Cole. |
| } |
| \keyword{classes} |
| \keyword{logic} |