iconv {base}R Documentation

Convert Character Vector between Encodings

Description

This uses system facilities to convert a character vector between encodings: the ‘i’ stands for ‘internationalization’.

Usage

iconv(x, from ="", to = "", sub = NA, mark = TRUE)

iconvlist()

Arguments

x A character vector, or an object to be converted to a character vector by as.character.
from A character string describing the current encoding.
to A character string describing the target encoding.
sub character string. If not 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 "byte", the indication is "<xx>" with the hex code of the byte.
mark logical, for expert use. Should encodings be marked?

Details

The names of encodings and which ones are available are platform-dependent. All R platforms support "" (for the encoding of the current locale), "latin1" and "UTF-8". Generally case is ignored when specifying an encoding.

On many platforms, including Windows, iconvlist provides an alphabetical list of the supported encodings. On others, the information is on the man page for iconv(5) or elsewhere in the man pages (but beware that the system command iconv may not support the same set of encodings as the C functions R calls). Unfortunately, the names are rarely common across platforms.

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

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

Encoding "ASCII" is also accepted, but prior to R 2.10.0 conversion to "ASCII" on Windows might have involved dropping accents.

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

"UTF8" will be accepted as meaning the (more correct) "UTF-8".

Value

A character vector of the same length and the same attributes as x (after conversion).

If mark = TRUE (the default) the elements of the result have a declared encoding if from is "latin1" or "UTF-8", or if from = "" and the current locale's encoding is detected as Latin-1 or UTF-8.

Implementation Details

iconv was optional before R 2.10.0, but its absence was deprecated in R 2.5.0.

There are three main implementations of iconv in use. glibc (as used on Linux) contains one. Several platforms supply GNU libiconv, including Mac OS X and Cygwin. On Windows we use a version of Yukihiro Nakadaira's win_iconv, which is based on Windows' codepages (but libiconv can be used by swapping a DLL). All three have iconvlist, ignore case in encoding names and support //TRANSLIT (but with different results, and for win_iconv currently a ‘best fit’ strategy is used except for to = "ASCII").

Most commercial Unixes contain an implemetation of iconv but none we have encountered have supported the encoding names we need: the “R Installation and Administration Manual” recommends installing libiconv on Solaris and AIX, for example.

There are other implementations, e.g. NetBSD uses one from the Citrus project (which does not support //TRANSLIT) and there is an older FreeBSD port (libiconv is usually used there): it has not been reported whether or not these work with R.

See Also

localeToCharset, file.

Examples

## not all systems have iconvlist
try(utils::head(iconvlist(), n = 50))

## Not run: 
## 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")

## End(Not run)

## 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")

[Package base version 2.11.0 Index]