Color to RGB Conversion

Description

“Any R color” to RGB (red/green/blue) conversion.

Usage

col2rgb(col)

Arguments

Details

For integer colors, 0 is shorthand for the current par("bg"), and NA means “nothing” which effectively does not draw the corresponding item.

For character colors, "NA" is equivalent to NA above.

Value

an integer matrix with three rows and number of columns the length (and names if any) as col.

Author(s)

Martin Maechler

See Also

rgb, colors, palette, etc.

Examples

col2rgb("peachpuff")
col2rgb(c(blu = "royalblue", reddish = "tomato")) # names kept

col2rgb(1:8)# the ones from the palette() :
pp <- palette(); names(pp) <- pp # add & use names :
stopifnot(col2rgb(1:8) ==
    print(col2rgb(pp)))

col2rgb(paste("gold", 1:4, sep=""))

stopifnot(col2rgb("#08a0ff") == c(8, 160, 255))
## all three kind of colors mixed :
col2rgb(c(red="red", palette= 1:3, hex="#abcdef"))

##-- NON-INTRODUCTORY examples --

grC <- col2rgb(paste("gray",0:100,sep=""))
stopifnot(grC["red",] == grC["green",],
          grC["red",] == grC["blue",],
          grC["red", 1:4] == c(0,3,5,8))
table(print(diff(grC["red",])))# `2' or `3': almost equidistant
## The `named' grays are in between {"slate gray" is not gray, strictly}
col2rgb(c(g66="gray66", darkg= "dark gray", g67="gray67",
          g74="gray74", gray =      "gray", g75="gray75",
          g82="gray82", light="light gray", g83="gray83"))

crgb <- col2rgb(cc <- colors())
colnames(crgb) <- cc
t(crgb)## The whole table

ccodes <- c(256^(2:0) %*% crgb)## = internal codes
## How many names are `aliases' of each other:
table(tcc <- table(ccodes))
length(uc <- unique(sort(ccodes))) # 502
## All the multiply named colors:
mult <- uc[tcc >= 2]
cl <- lapply(mult, function(m) cc[ccodes == m])
names(cl) <- apply(col2rgb(sapply(cl, function(x)x[1])),
                   2, function(n)paste(n, collapse=","))
str(cl)
## Not run: 
 if(require(xgobi)) { ## Look at the color cube dynamically :
   tc <- t(crgb[, !duplicated(ccodes)])
   table(is.gray <- tc[,1] == tc[,2] & tc[,2] == tc[,3])# (397, 105)
   xgobi(tc, color = c("gold", "gray")[1 + is.gray])
 }

## End(Not run)