Re: [R] hex format

From: Jan T. Kim <jtk_at_cmp.uea.ac.uk>
Date: Fri 08 Apr 2005 - 04:51:26 EST

On Thu, Apr 07, 2005 at 11:58:48AM -0500, Earl F. Glynn wrote:
> "Duncan Murdoch" <murdoch@stats.uwo.ca> wrote in message
> news:42555459.6040106@stats.uwo.ca...
> > > Seems to me the conversion from hex to decimal should be system
> independent
> > > (and makes working with colors much more convenient). Why isn't this
> system
> > > independent now?
> >
> > Presumably because nobody thought it was important enough to make it so.
> > R isn't a low level system programming language, so why should it
> > treat hex specially?
>
> 1) While generally I'd agree with your statement, manipulating colors is one
> place the ability to convert to/from hex would be quite nice.
>
> > rgb(1,0,0.5)
> [1] "#FF0080"
>
> rgb returns a hex string and then R makes manipulating this string somewhat
> difficult.

I'd like to second this opinion. It just occasionally happens that data are available in some variant of hex format, and I've had the impression that getting such data into R is a bit less convenient than it could be.

> One might want to use such color values to convert to a
> different color space, perform some sort of manipulation in that other color
> space, and then convert back to rgb.
>
> 2) I would think that one of R's mathematical abilities would be to provide
> a way to convert from any base to base 10, and from base 10 to any base. I
> haven't found this general math tool yet in R. Working with base-16 (or
> even base 2 sometimes) could be done with such a general math tool.

In fact, the ANSI C function strtol already provides conversion to any base between 2 and 36, so R's mathematical capabilities don't even need to be invoked here.

An R function strtol(x, base), x being a character variable and base an integer between 2 and 36, would probably add a bit of convenience. I've never programmed that, though -- seems that I'm one of those to whom this hasn't been important enough.

If it is done some day, I'd favour the strtol function over having as.numeric interpret the (rather C-ish) 0x prefix. I wasn't aware that this currently works on some platforms (and I'm glad it doesn't interpret the 0 prefix for octal, as C does, making 007 legal and 008 not. ;-) )

Best regards, Jan

-- 
 +- Jan T. Kim -------------------------------------------------------+
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Received on Fri Apr 08 04:02:29 2005

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