| col2rgb {grDevices} | R Documentation |
“Any R color” to RGB (red/green/blue) conversion.
col2rgb(col, alpha = FALSE)
col |
vector of any of the three kind of R colors, i.e., either
a color name (an element of colors()), a hexadecimal
string of the form "#rrggbb", or an integer i meaning
palette()[i]. |
alpha |
logical value indicating whether alpha channel values should be returned. |
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.
an integer matrix with three or four rows and number of columns the length
(and names if any) as col.
Martin Maechler
col2rgb("peachpuff")
col2rgb(c(blu = "royalblue", reddish = "tomato")) # names kept
col2rgb(1:8)# the ones from the palette() :
col2rgb(paste("gold", 1:4, sep=""))
col2rgb("#08a0ff")
## 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=""))
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=","))
utils::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)