57 lines
1.6 KiB
R
57 lines
1.6 KiB
R
%% ESS BUG: Indentation ([Tab]) does not work if point is after \arguments{..}
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%% ------- almost surely because of the (non-escaped) "[".
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%% and this, all below is original from the R sources (R-devel, 2014-03-05)
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% File src/library/base/man/Extract.factor.Rd
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% Part of the R package, http://www.R-project.org
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% Copyright 1995-2010 R Core Team
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% Distributed under GPL 2 or later
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\name{Extract.factor}
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\title{Extract or Replace Parts of a Factor}
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\alias{[.factor}
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\alias{[<-.factor}
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\alias{[[.factor}
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\alias{[[<-.factor}
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\description{
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Extract or replace subsets of factors.
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}
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\usage{
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\method{[}{factor}(x, \dots, drop = FALSE)
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\method{[[}{factor}(x, \dots)
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\method{[}{factor}(x, \dots) <- value
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\method{[[}{factor}(x, \dots) <- value
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}
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\arguments{
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\item{x}{a factor}
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\item{\dots}{a specification of indices -- see \code{\link{Extract}}.}
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\item{drop}{logical. If true, unused levels are dropped.}
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\item{value}{character: a set of levels. Factor values are coerced to
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character.}
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}
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\value{
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A factor with the same set of levels as \code{x} unless \code{drop = TRUE}.
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}
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\details{
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When unused levels are dropped the ordering of the remaining levels is
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preserved.
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If \code{value} is not in \code{levels(x)}, a missing value is
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assigned with a warning.
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Any \code{\link{contrasts}} assigned to the factor are preserved
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unless \code{drop = TRUE}.
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The \code{[[} method supports argument \code{exact}.
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}
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\seealso{
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\code{\link{factor}}, \code{\link{Extract}}.
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}
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\examples{
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## following example(factor)
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(ff <- factor(substring("statistics", 1:10, 1:10), levels = letters))
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ff[, drop = TRUE]
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factor(letters[7:10])[2:3, drop = TRUE]
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}
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\keyword{category}
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