| iconv {base} | R Documentation |
This uses system facilities to convert a character vector between encodings: the ‘i’ stands for ‘internationalization’.
iconv(x, from = "", to = "", sub = NA, mark = TRUE, toRaw = FALSE) iconvlist()
x |
A character vector, or an object to be converted to a character
vector by |
from |
A character string describing the current encoding. |
to |
A character string describing the target encoding. |
sub |
character string. If not |
mark |
logical, for expert use. Should encodings be marked? |
toRaw |
logical. Should a list of raw vectors be returned rather than a character vector? |
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 valid across all 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, and on most systems
"C" and "POSIX" are synonyms for ASCII.
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".
If toRaw = FALSE (the default), the value is a character vector
of the same length and the same attributes as x (after
conversion to a character vector).
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.
If toRaw = TRUE, the value is a vector of the same length and
the same attributes as x whose elements are either NULL
(if conversion fails) or a raw vector.
For iconvlist(), a character vector (typically of a few hundred
elements).
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, FreeBSD and Cygwin.
On Windows we use a version of Yukihiro Nakadaira's win_iconv,
which is based on Windows' codepages. 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 GNU 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.
Note that you cannot rely on invalid inputs being detected, especially
for to = "ASCII" where some implementations allow 8-bit
characters and pass them through unchanged or with transliteration.
## In principle, 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 old R help files (they are nowadays in UTF-8)
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")
## and for Windows' 'Unicode'
str(xx <- iconv(x, "latin1", "UTF-16LE", toRaw = TRUE))
iconv(xx, "UTF-16LE", "UTF-8")