The R Project SVN R

% File src/library/base/man/iconv.Rd
% Part of the R package, http://www.R-project.org
% Copyright 1995-2007 R Core Development Team
% Distributed under GPL 2 or later

\name{iconv}
\alias{iconv}
\alias{iconvlist}
\concept{encoding}
\title{Convert Character Vector between Encodings}
\description{
  This uses system facilities to convert a character vector between
  encodings: the \sQuote{i} stands for \sQuote{internationalization}.
}
\usage{
iconv(x, from ="", to = "", sub = NA)

iconvlist()
}

\arguments{
  \item{x}{A character vector, or an object to be converted to a character
    vector by \code{\link{as.character}}.}
  \item{from}{A character string describing the current encoding.}
  \item{to}{A character string describing the target encoding.}
  \item{sub}{character string.  If not \code{NA} it is used to replace
    any non-convertible bytes in the input.  (This would normally be a
    single character, but can be more.)  If \code{"byte"}, the indication is
    \code{"<xx>"} with the hex code of the byte.}
}

\details{
  The names of encodings and which ones are available (and indeed, if
  any are) is platform-dependent.  On all systems that support
  \code{iconv} you can use \code{""} for the encoding of the current
  locale, as well as \code{"latin1"} and \code{"UTF-8"}.

#ifdef unix
  On many platforms \code{iconvlist} provides an alphabetical list of
  the supported encodings.  On others, the information is on the man
  page for \code{iconv(5)} or elsewhere in the man pages (and beware
  that the system command \code{iconv} may not support the same set of
  encodings as the C functions \R calls).
  Unfortunately, the names are rarely common across platforms.
#endif
#ifdef windows
  \code{iconvlist} provides an alphabetical list of the supported encodings.
#endif

  Elements of \code{x} which cannot be converted (perhaps because they
  are invalid or because they cannot be represented in the target
  encoding) will be returned as \code{NA} unless \code{sub} is specified.

  Most versions of \code{iconv} will allow transliteration by appending
  \code{//TRANSLIT} to the \code{to} encoding: see the examples.

  Any encoding bits (see \code{\link{Encoding}}) on elements of \code{x}
  are ignored: they will always be translated as if from \code{from}
  even if declared otherwise.

  \code{"UTF8"} will be accepted as meaning the (more correct) \code{"UTF-8"}.
}
\value{
  A character vector of the same length and the same attributes as
  \code{x} (after conversion).

  The elements of the result have a declared encoding if \code{from} is
  \code{"latin1"} or \code{"UTF-8"}, or if \code{from = ""} and the
  current locale's encoding is detected as Latin-1 or UTF-8.
}
\note{
  Not all platforms support these functions, although almost all
  support \code{iconv}.  See also \code{\link{capabilities}("iconv")}.
}
\seealso{
  \code{\link{localeToCharset}}, \code{\link{file}}. 
}
\examples{\donttest{
utils::head(iconvlist(), n = 50)

\dontrun{
## convert from Latin-2 to UTF-8: two of the glibc iconv variants.
iconv(x, "ISO_8859-2", "UTF-8")
iconv(x, "LATIN2", "UTF-8")
}

## Both x below are in latin1 and will only display correctly in a
## locale that can represent and display latin1.
x <- "fa\xE7ile"
Encoding(x) <- "latin1"
x
charToRaw(xx <- iconv(x, "latin1", "UTF-8"))
xx

iconv(x, "latin1", "ASCII")          #   NA
iconv(x, "latin1", "ASCII", "?")     # "fa?ile"
iconv(x, "latin1", "ASCII", "")      # "faile"
iconv(x, "latin1", "ASCII", "byte")  # "fa<e7>ile"

# Extracts from R help files
x <- c("Ekstr\xf8m", "J\xf6reskog", "bi\xdfchen Z\xfcrcher")
Encoding(x) <- "latin1"
x
try(iconv(x, "latin1", "ASCII//TRANSLIT"))  # platform-dependent
iconv(x, "latin1", "ASCII", sub="byte")
}}
\keyword{ character }
\keyword{ utilities }