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% File src/library/base/man/unique.Rd
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% File src/library/base/man/unique.Rd
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% Part of the R package, https://www.R-project.org
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% Part of the R package, https://www.R-project.org
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% Copyright 1995-2014 R Core Team
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% Copyright 1995-2016 R Core Team
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% Distributed under GPL 2 or later
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% Distributed under GPL 2 or later
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\name{unique}
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\name{unique}
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\alias{unique}
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\alias{unique}
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\alias{unique.default}
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\alias{unique.default}
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\emph{duplicated} and not just \emph{repeated} elements/rows. That
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\emph{duplicated} and not just \emph{repeated} elements/rows. That
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is, an element is omitted if it is equal to any previous element and
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is, an element is omitted if it is equal to any previous element and
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not just if it is equal the immediately previous one. (For the
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not just if it is equal the immediately previous one. (For the
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latter, see \code{\link{rle}}).
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latter, see \code{\link{rle}}).
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Missing values are regarded as equal, but \code{NaN} is not equal to
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Missing values (\code{"\link{NA}"}) are regarded as equal, numeric and
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\code{NA_real_}. Character strings are regarded as equal if they are
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complex ones differing from \code{NaN}; character strings will be compared in a
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in different encodings but would agree when translated to UTF-8.
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\dQuote{common encoding}; for details, see \code{\link{match}} (and
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\code{\link{duplicated}}) which use the same concept.
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Values in \code{incomparables} will never be marked as duplicated.
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Values in \code{incomparables} will never be marked as duplicated.
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This is intended to be used for a fairly small set of values and will
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This is intended to be used for a fairly small set of values and will
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not be efficient for a very large set.
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not be efficient for a very large set.
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When used on a data frame with more than one column, or an array or
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When used on a data frame with more than one column, or an array or
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matrix when comparing dimensions of length greater than one, this
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matrix when comparing dimensions of length greater than one, this
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tests for identity of character representations. This will
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tests for identity of character representations. This will
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catch people who unwisely rely on exact equality of floating-point
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catch people who unwisely rely on exact equality of floating-point
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numbers!
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numbers!
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Character strings will be compared as byte sequences if any input is
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marked as \code{"bytes"} (see \code{\link{Encoding}}).
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}
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}
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\value{
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\value{
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For a vector, an object of the same type of \code{x}, but with only
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For a vector, an object of the same type of \code{x}, but with only
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one copy of each duplicated element. No attributes are copied (so
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one copy of each duplicated element. No attributes are copied (so
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the result has no names).
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the result has no names).
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