Re: [R] col2rgb() function

Sun, 23 Jul 2023 13:13:52 -0700

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 <bbol...@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

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