order() fails on a chr object of class "AsIs" with "\265" in it

On Fri, 15 Jan 2010, Don MacQueen wrote:

Here's an example (session info at the end).

 tmpv <- c('\265g/L','Bq/L')
 order(tmpv)

[1] 2 1

 tmpv <- I(tmpv)
 order(tmpv)

Error in if (xi > xj) 1L else -1L : missing value where TRUE/FALSE needed

 foov <- gsub('\265','',tmpv)
 order(foov)

[1] 2 1

 str(tmpv)

Class 'AsIs'  chr [1:2] "\265g/L" "Bq/L"

 str(foov)

Class 'AsIs'  chr [1:2] "g/L" "Bq/L"

I can easily work around this in my scripts, but shouldn't order() 
succeed with such an object?

Not in the C locale.  There is no pre-defined ordering for non-ASCII 
characters in that locale and the string is invalid in a strict C 
locale.

(I suppose this could be Mac-specific, but I'm assuming it's not...)

No, but the handling of invalid strings in C is OS-specific.

For context:
The character "\265" causes the Greek letter mu to be displayed in 
various output devices. For example, the character vector 
eventually gets written to an html file, which when displayed in 
Firefox (Mac) is displayed as Greek mu. Also in Excel 2004 (Mac).

I first wrote these scripts 6 years ago, when "\265" was a way I 
could find to display the Greek mu in output text files of various 
kinds. They worked as recently as 3 months ago. Maybe there's a 
better way now to display a mu in text-based contexts?

Use UTF-8 and Unicode \u03BC (http://*www.*alanwood.net/unicode/greek.html).

The issue is that you need a xtfrm method for 'AsIs': it falls back 
to comparisons via .gt and those (correctly) fail.

xtfrm.AsIs <- function(x) xtfrm(unclass(x))

would keep get you going until you fix the scripts.

 sessionInfo()

R version 2.10.1 (2009-12-14)
i386-apple-darwin8.11.1

locale:
[1] C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

Thanks
-Don
--
--------------------------------------
Don MacQueen
Environmental Protection Department
Lawrence Livermore National Laboratory
Livermore, CA, USA
925-423-1062

--
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://*www.*stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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