CODEWITHSUNDEEP
rggplot2rgb
Adonis Cedeño
Adonis Cedeño

Reputation: 167

How to know the rgb colour code for a certain named color in R?

In a ggplot2 plot, I want to use the function:

scale_fill_manual(
values = c(
'mediumorchid2',
'gold1',
'red'
)

I know the RGB code colour for 'red': #FF0000

The colors 'mediumorchid2' or 'gold1' also have this kind of code. How can I get it?

Upvotes: 2

Views: 1291

Answers (2)

duckmayr
duckmayr

Reputation: 16940

First, you're talking about the hex representation, not the RGB. The RGB representation is three numbers (either between 0 and 1 or 0 and 255) giving the red, green, and blue levels.

To get the RGB representation, you can just use the base function col2rgb():

col2rgb('mediumorchid2')
#       [,1]
# red    209
# green   95
# blue   238

I have long had a personal convenience function for getting the hex representation, as it's a task I need to do often:

col2hex <- function(x, alpha = "ff") {
    RGB <- col2rgb(x)
    return(apply(RGB, 2, function(C) {
        paste(c("#", sprintf("%02x", C), alpha), collapse = "")
    }))
}
col2hex('mediumorchid2')
# [1] "#d15feeff"

Update:

Gordon Shumway's excellent answer mentions that apparently there is a package with such a function already! I would recommend that. However, I leave my answer up both for the discussion of RGB vs. hex and in case you don't want a dependency on gplot.

Upvotes: 3

GordonShumway
GordonShumway

Reputation: 2056

The gplots package has a function named col2hex():

library(gplots)
col2hex("gold1")
"#FFD700"

Upvotes: 5

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