To sort colors by hue in R, we need to convert the colors from HEX (hexadecimal) to RGB (red-green-blue), compute the hue values and then sort them.
Example
The I Want Hue website provides a really nice tool to get a list of colors. And it has an option to sort the colors by hue values. However, if we copy two lists of colors, how can we sort the concatenated list?
hex_a = c("#d52400", "#ffa888", "#ffb46b", "#d8c93a", "#5d6319", "#72df21",
"#328100", "#b9cbbb", "#01ca42", "#00b773", "#01bdce", "#13d8fc",
"#91ceec", "#2b6294", "#0269f4", "#285cb1", "#5b3de8", "#d0bef0",
"#873fa3", "#e162ff", "#ff55ea", "#ab2080", "#f3009e", "#ff99c6",
"#ff60a6", "#ff7f97", "#a23b49")
hex_b = c("#a33f1a", "#ffa465", "#e7c352", "#60620d", "#849300", "#88da67",
"#008e25", "#019f50", "#b5cbc5", "#01b495", "#85d4cd", "#007681",
"#82d1ea", "#029bcd", "#72a7ff", "#0055f0", "#5254b3", "#63568f",
"#cc7eff", "#d000c8", "#fdabf3", "#ff63d8", "#a1317d", "#98406d",
"#c00059", "#ffa3a9", "#ff414a")
hex = c(hex_a, hex_b)> hex[1:6]
[1] "#d52400" "#ffa888" "#ffb46b" "#d8c93a" "#5d6319" "#72df21"barplot(rep(1, length(hex)), col = hex, axes = F)
From HEX to RGB colors
This is how we can apply the col2rgb function from base R (already used in my post about the conversion between HEX and RGB colors) on a vector of colors:
rgb = sapply(hex, function(x){col2rgb(x)})> rgb[,1:6]
#d52400 #ffa888 #ffb46b #d8c93a #5d6319 #72df21
[1,] 213 255 255 216 93 114
[2,] 36 168 180 201 99 223
[3,] 0 136 107 58 25 33The first row corresponds to red values, the second one to green values and the last one to blue values.
From RGB colors to hue values
This is how we can apply a custom function (that comes from my post about the conversion between RGB and HSL colors) on a vector of colors:
from_rgb_to_hue = function(rgb){
R = rgb[1] / 255
G = rgb[2] / 255
B = rgb[3] / 255
M = max(c(R, G, B))
m = min(c(R, G, B))
C = M - m
if (C == 0){
H = 0
} else {
if (M == R){
H = ((G - B) / C) %% 6
} else if (M == G){
H = ((B - R) / C) + 2
} else if (M == B){
H = ((R - G) / C) + 4
}
}
return(H * 60)
}
hue = apply(rgb, 2, function(x){from_rgb_to_hue(x)})> hue[1:6]
#d52400 #ffa888 #ffb46b #d8c93a #5d6319 #72df21
10.14085 16.13445 29.59459 54.30380 64.86486 94.42105 Sort hue values
barplot(rep(1, length(hex)), col = hex[order(hue)], axes = F)
Conclusion
To sum up, we can sort HEX colors by hue in R by converting them from HEX to RGB and then by computing the hue values. Is this blog post helpful to you?
