[R] col2rgb() function

[Nick Wray]

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]]