R/rgb2hex.R

In tsieger/tsiMisc: Miscelaneous utility functions, mostly related to exploratory statistical analysis

rgb2hex <- structure(
function # Convert RGB color to text hexadecimal representation.
##description<<
##
## Convert an RGB color to '#RRGGBB' representation.
## Useful e.g. to use a mixed color (as mixed by the \code{\link[colorspace]{mixcolor}}
## function) as a color in calls to raw graphics function. See examples.
##
## see https://gist.github.com/mbannert/e9fcfa86de3b06068c83
(r, ##<< red color component, or a column 3-element vector of R,G,B values, or an object of class 'RGB'
g = NULL, ##<< optional green color component
b = NULL ##<< optional blue color component
){
  if (is.null(r)) {
    rv<-NULL
  } else if (inherits(r,'RGB')) {
    tmp<-coords(r)
    rv<-rgb(tmp[,1], tmp[,2], tmp[,3], maxColorValue = 255)
  } else if (is.matrix(r)&&ncol(r)==3) {
    tmp<-coords(RGB(r))
    rv<-rgb(tmp[,1], tmp[,2], tmp[,3], maxColorValue = 255)
  } else if (length(r)==3) {
    rv<-rgb(r[1], r[2], r[3], maxColorValue = 255)
  } else {
    rv<-rgb(r, g, b, alpha = 0, maxColorValue = 255)
  }
  return(rv)
},ex=function() {
  require(colorspace)

  col1<-RGB(t(col2rgb('yellow')))
  col2<-RGB(t(col2rgb('black')))
  mixCol<-mixcolor(.3,col1,col2)
  col<-rgb2hex(mixCol)
  plot(c(0,1,2),c(0,0,0),xlim=c(-.5,2.5),ty='p',pch=21,cex=15,col='black',
    bg=c('yellow',col,'black'),frame=FALSE,xlab='',ylab='',xaxt='n',yaxt='n')
})