[R] col2rgb() function

[Nick Wray]

Thanks v useful to know Nick

On Sun, 23 Jul 2023 at 21:13, Achim Zeileis <Achim.Zeileis using uibk.ac.at>
wrote:

> Just one addition which may or may not be useful: The color palette you
> use is also known as "Okabe-Ito" and it is the default set of colors in
> the palette.colors() function. This function also has an optional alpha
> argument. So if you want to generate these colors with an alpha of 0.3 you
> can also do:
>
> palette.colors(8, alpha = 0.3)
>
> or more explicitly
>
> palette.colors(8, palette = "Okabe-Ito", alpha = 0.3)
>
> On Sun, 23 Jul 2023, Nick Wray wrote:
>
> > 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]]
> >
> > ______________________________________________
> > 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.
> >

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