col2rgb
Color to RGB Conversion
R color to RGB (red/green/blue) conversion.
Usage
col2rgb(col, alpha = FALSE)Arguments
- col
vector of any of the three kinds of R color specifications, i.e., either a color name (as listed by
colors()), a hexadecimal string of the form"#rrggbb"or"#rrggbbaa"(seergb), or a positive integerimeaningpalette()[i].- alpha
logical value indicating whether the alpha channel (opacity) values should be returned.
Details
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.
Value
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.
See Also
The newer, more flexible interface, convertColor().
Examples
library(grDevices)
# NOT RUN {
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])
}
# }