[R] col2rgb() function

[Nick Wray]

Thanks That works nicely  Nick

On Sun, 23 Jul 2023 at 19:26, Ben Bolker <bbolker using gmail.com> wrote:

>    Does adjustcolor() help?
>
> cb8<- c("#000000", "#E69F00", "#56B4E9", "#009E73","#F0E442", "#0072B2",
>     "#D55E00", "#CC79A7")
> plot(0,0,xlim=c(1,8),ylim=c(0,1))
> points(1:8,rep(0.5,8),col=cb8,pch=19,cex=2)
> points(1:8,rep(0.75,8),col=adjustcolor(cb8, alpha.f = 0.3), pch=19,cex=2)
>
> On 2023-07-23 2:15 p.m., Nick Wray wrote:
> > Hello  I have a palette vector of colour blind colours (in hexadecimal)
> > which I’m using for plots, but they are not see-through, and as I wanted
> to
> > overlay some histograms I wanted to convert these colours to rgb, when
> you
> > can set the opacity.
> >
> > I have found the function col2rgb(), which works in the sense that it
> gives
> > a vector of numbers but these don’t work directly in rgb because they are
> > too big.  If I divide through to make them all less than 1 I don’t get
> the
> > corresponding colour-blind hue, but something somewhat off.
> >
> > Here is the colour-blind palette in a plot:
> >
> >
> > *cb8<- c("#000000", "#E69F00", "#56B4E9", "#009E73","#F0E442", "#0072B2",
> > "#D55E00", "#CC79A7")*
> >
> > *plot(0,0,xlim=c(1,8),ylim=c(0,1))*
> >
> > *points(1:8,rep(0.5,8),col=cb8,pch=19,cex=2)*
> >
> >
> >
> > so if I try to convert the red dot ("#D55E00") (number 7) I get
> >
> > *col2rgb("#D55E00"*
> >
> >    [,1]
> >
> > red    213
> >
> > green   94
> >
> > blue     0
> >
> > *points(7,0.25,col=rgb(rgb(213,94,0)),pch=19,cex=2)*
> >
> > gives me an error message and although if  I divide through
> >
> > *points(7,0.25,col=rgb(213/307,94/307,0),pch=19,cex=2)*
> >
> > gives me a reddish dot, but not the same as in the colour-blind palette
> >
> >
> >
> > Somewhat mystified.  Can anyone help?? Thanks Nick Wray
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

	[[alternative HTML version deleted]]