[Rd] Small change to plot.xy

[ripley@stats.ox.ac.uk]

*Not* codes! Unclass perhaps.

However, why should  col=factor(c("red", "blue", "green"))
not as naturally coerce to character.

I think we do need to get the user to specify what is meant, as now.
There are lots of examples of this sort of thing in MASS, BTW.


On Fri, 22 Nov 2002, Jonathan Rougier wrote:

> Hi everyone,
>
> Is there any reason why we should not automatically coerce a factor
> supplied as an argument to col in a plotting function?  The following
> modification (to R-1.6.1) seems pretty harmless
>
> > plot.xy
> function (xy, type, pch = 1, lty = "solid", col = par("fg"),
>     bg = NA, cex = 1, ...)
> {
>     if (is.factor(col))
>         col <- codes(col)
>     .Internal(plot.xy(xy, type, pch, lty, col, bg, cex, ...))
> }
> <environment: namespace:base>
>
> and I think it is natural and not really wrong to want to type, say,
>
> > data(iris)
> > pairs(iris[, 1:4], col = iris[, 5])
>
> and get the colours.
>
> Cheers, Jonathan.
>
> --
> Jonathan Rougier                       Science Laboratories
> Department of Mathematical Sciences    South Road
> University of Durham                   Durham DH1 3LE
> tel: +44 (0)191 374 2361, fax: +44 (0)191 374 7388
> http://www.maths.dur.ac.uk/stats/people/jcr/jcr.html
>
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-- 
Brian D. Ripley,                  ripley@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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