50 Colors

library(rtemis)
library(ggplot2)
theme_set(theme(text = element_text(family = "Helvetica")))

Colors in R can be defined in many different ways:

Using names: colors() gives all available options
Using a hexadecimal RGB code in the form #RRGGBBAA, e.g. #FF0000FF for opaque red. Here, the max value is “FF” which corresponds to 255.
Using the rgb(red, green, blue, alpha) function (outputs a hex number)
Using the hsv(h, s, v, alpha) function for the HSV color system (also outputs a hex number)
Using integers: these index the output of palette(), whose defaults can be changed by the user (e.g. palette("cyan", "blue", "magenta", "red"))

50.1 Color names

There is a long list of color names R understands, and can be listed using colors().

They can be passed directly as characters.

Shades of gray are provided as gray0/grey0 (white) to gray100/grey100 (black).

An extra wide PDF with all built-in R colors is available here:

50.2 Hexadecimal codes

Hexadecimal color codes are characters starting with the pound sign, followed by 4 pairs of hex codes representing Red, Green, Blue, and Alpha values. Since RGB values go from 0 to 255, hex goes from 00 to FF. You can convert decimal to hex using as.hexmode():

as.hexmode(0)

[1] "0"

as.hexmode(127)

[1] "7f"

as.hexmode(255)

[1] "ff"

The last two values for the alpha setting are optional: if not included, defaults to max, i.e. opaque.

50.3 RGB

rgb(0, 0, 1)

[1] "#0000FF"

Note the default maxColorValue = 1, set to 255 to use the usual RGB range of 0 to 255:

rgb(0, 0, 255, maxColorValue = 255)

[1] "#0000FF"

50.4 HSV

Color can also be parameterized using the hue, saturation, and value system (HSV). Each range from 0 to 1.
Simplistically: Hue controls the color. Saturation 1 is max color and 0 is white. Value 1 is max color and 0 is black.

hsv(1, 1, 1)

[1] "#FF0000"

50.5 Transparency

An easy way to add transparency to any color is using adjustcolor():

For example, to get 50% transparent blue:

adjustcolor("blue", alpha.f = 0.5)

[1] "#0000FF80"

“FF” is hex for 255, and “80” in hex is 128, therefore you can also define the above color as “#0000FF80”, i.e. 0 red, 0 green, 255 blue, 128 alpha.