[R-pkg-devel] problem with locale-dependent order()

[Jim Hester]

Alex,

'with_collate' is one of the functions included in the withr package (
https://cran.rstudio.com/web/packages/withr/).
So you could simply write

  sort_c <- function(x) withr::with_collate("C", sort(x))

The usage semantics and implementation are essentially identical to what
Hadley described.

Jim

On Sun, Sep 20, 2015 at 1:22 PM, Hadley Wickham <h.wickham at gmail.com> wrote:

> Hi Alex,
>
> As far as I know, that's the best solution. In roxygen, I've wrapped
> it up with a couple of helpers:
>
> set_collate <- function(locale) {
>   cur <- Sys.getlocale(category = "LC_COLLATE")
>   Sys.setlocale(category = "LC_COLLATE", locale = locale)
>   cur
> }
>
> with_collate <- function(locale, code) {
>   old <- set_collate(locale)
>   on.exit(set_collate(old))
>
>   force(code)
> }
>
> sort_c <- function(x) with_collate("C", sort(x))
>
> Hadley
>
> On Fri, Sep 18, 2015 at 4:25 PM, Alex Deckmyn <alex.deckmyn at meteo.be>
> wrote:
> > Hi,
> >
> > For an update of the maps package, I have run into a bug caused by the
> locale-depent behaviour of order().
> > In a certain function, the polygon names of the world map are lexically
> sorted with order() prior to being sent to a C routine. That routine
> expects them to be sorted according to ASCII rules, but that is not the
> result I get. The main culprit is the colon used to identify sub-regions.
> For instance, in my locale (en_GB_UTF-8), I get
> >
> > "uk:northen ireland" < "ukrain" < "uk:scotland"
> >
> > which is not the order expected by C. I guess some language settings
> would also cause other unexpected results.
> >
> > Apart from the pain of fixing uk/ukrain ambiguities, is there a safe way
> to fix this order() in a package? An obvious solution seems to be
> >
> > lcc <- Sys.getlocale("LC_COLLATE")
> > Sys.setlocale("LC_COLLATE","C")
> > ord.nam <- order(nam)
> > Sys.setlocale("LC_COLLATE",lcc)
> >
> > This seems to work fine on my linux PC, but I am not sure about other
> platforms (Windows, OS-X...), though the "C" locale should be standard. Is
> this safe? Or is there a better way to get the right ordering?
> >
> > Alex
> >
> > ---
> > Dr. Alex Deckmyn e-mail: alex.deckmyn at meteo.be
> > Royal Meteorological Institute http://www.meteo.be
> > Ringlaan 3, 1180 Ukkel, Belgium tel. (32)(2)3730646
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-package-devel at r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-package-devel
>
>
>
> --
> http://had.co.nz/
>
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