| col2rgb {grDevices} | R Documentation |
R color to RGB (red/green/blue) conversion.
col2rgb(col, alpha = FALSE)
col |
vector of any of the three kinds of R color specifications,
i.e., either a color name (as listed by |
alpha |
logical value indicating whether the alpha channel (opacity) values should be returned. |
NA (as integer or character) and "NA" mean transparent.
Values of col not of one of these types are coerced: real
vectors are coerced to integer and other types to character. (factors
are coerced to character: in all other cases the class is
ignored when doing the coercion.)
Zero and negative values of col are an error.
An integer matrix with three or four (for alpha = TRUE) rows
and number of columns the length of col. If col has
names these are used as the column names of the return value.
Martin Maechler and the R core team.
The newer, more flexible interface, convertColor().
col2rgb("peachpuff")
col2rgb(c(blu = "royalblue", reddish = "tomato")) # note: colnames
col2rgb(1:8) # the ones from the palette() (if the default)
col2rgb(paste0("gold", 1:4))
col2rgb("#08a0ff")
## all three kinds of color specifications:
col2rgb(c(red = "red", hex = "#abcdef"))
col2rgb(c(palette = 1:3))
##-- NON-INTRODUCTORY examples --
grC <- col2rgb(paste0("gray", 0:100))
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)