[R] General means of matching a color specification to an official R color name

Romain Francois romain.francois at dbmail.com
Wed Oct 14 13:22:25 CEST 2009


On 10/14/2009 12:26 PM, Romain Francois wrote:
>
> On 10/14/2009 12:05 AM, Barry Rowlingson wrote:
>>
>> On Tue, Oct 13, 2009 at 10:58 PM, Bryan Hanson<hanson at depauw.edu> wrote:
>>> Works perfectly! Thanks Barry. I had actually seen some suggestions on
>>> using a distance, but by then I was thinking about hcl spaces and
>>> distance
>>> isn't so as simple there. I'm too tired I think.
>>>
>>> Anyway, you've got me running again! Thanks, Bryan
>>
>> There's a CPAN module for Perl that does hcl colour similarity:
>>
>> >http://search.cpan.org/~mbarbon/Color-Similarity-HCL-0.04/lib/Color/Similarity/HCL.pm
>>
>>
>> the Perl code is pretty neat, looks easy to R-ify - released under
>> the perl license.
>>
>> Barry
>
> There are a few unexported functions in the xterm256 package to deal
> with this.
>
>  > colors()[ xterm256:::closest.character( "#aabbcc" ) ]
> [1] "gold4"

Actually that is wrong closest.character gives you the index of the 
closest xterm256 color, as in : http://frexx.de/xterm-256-notes/

sorry for the misleading answer ...

> The package pretends it writes the text using the background of
> foreground color as usually represented in R, but it actually first
> grabs the closest color (in the RGB space according to the euclidian
> metric, I have no idea whether a different space or a different metric
> would be better)
>
> This presentation might give a clue :
> http://www.agrocampus-ouest.fr/math/useR-2009//slides/Zeileis+Hornik+Murrell.pdf
>
>
> Romain
>


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Romain Francois
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