Re: [Rd] use of UTF-8 \uxxxx escape sequences in function arguments

From: Simon Urbanek <simon.urbanek_at_r-project.org>
Date: Thu, 19 Jan 2012 20:58:54 -0500

On Jan 19, 2012, at 6:39 PM, Thomas Zumbrunn wrote:

> On Thursday 19 January 2012, peter dalgaard wrote:

>> On Jan 18, 2012, at 23:54 , Thomas Zumbrunn wrote:
>>>  plain("Zürich")  ## works
>>>  plain("Z\u00BCrich")  ## fails
>>>  escaped("Zürich")  ## fails
>>>  escaped("Z\u00BCrich")  ## works
>> 
>> Using the correct UTF-8 code helps quite a bit:
>> 
>> U+00BC	¼	c2 bc	VULGAR FRACTION ONE QUARTER
>> U+00FC	ü	c3 bc	LATIN SMALL LETTER U WITH DIAERESIS

>
> Thank you for pointing that out. How embarrassing - I systematically used the
> wrong representations. Even worse, I didn't carefully read "Writing R
> Extensions" which speaks of "Unicode as \uxxxx escapes" rather than "UTF-8 as
> \uxxxx escapes", so e.g. looking up the UTF-16 byte representations would have
> done the trick.
>
> I didn't find a recommended method of replacing non-ASCII characters with
> Unicode \uxxxx escape sequences and ended up using the Unix command line tool
> "iconv". However, the iconv version installed on my GNU/Linux machine
> (openSUSE 11.4) seems to be outdated and doesn't support the very useful "--
> unicode-subst" option yet. I installed "libiconv" from
> http://www.gnu.org/software/libiconv/, and now I can easily replace all non-
> ASCII characters in my UTF-8 encoded R files with:
>
> iconv -f UTF-8 -t ASCII --unicode-subst="\u%04X" my-utf-8-encoded-file.R
>

You can actually do that with R alone:

## you'll have to make sure that you're in C locale so R does the conversion for you Sys.setlocale(,"C")

utf8conv <- function(conn) gsub("<U\\+([0-9A-F]{4})>","\\\\u\\1",capture.output(writeLines(readLines(conn,encoding="UTF-8"))))

> writeLines(utf8conv("test.txt"))

M\u00F6gliche L\u00F6sung
ne nebezpe\u010Dn\u00E9

Cheers,
Simon



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