Colors

Make transparent colors

Using rgb()

color  <- col2rgb('dodgerblue3')
alpha  <- 0.5
plot(..., col = rgb(color[1], color[2], color[3], alpha = 255 * alpha, max = 255))

Using HEX

The HEX color should be in the format #RRGGBBAA, where R is for red, G is for green, B is for blue and A is for alpha in hexadecimals.

# Hex color example of dodgerblue3 with alpha of 0.5.
color <- '#1874cd80'
plot(..., col = color)

Conversion between HEX and decimal in R

# hex to decimal
as.integer(paste0('0X', 'ff'))

## [1] 255

# decimal to hex
as.hexmode(255)

## [1] "ff"

See also r hex convertor hex_color() a hex color converter using x11_hex() from the package diagrammeR.

Palettes

A couple nice colors for graphs. See also Colorbrewer for many more examples.

Color example

palette  <- c(rgb(166, 206, 227, maxColorValue = 255),
              rgb(31 , 120, 180, maxColorValue = 255), # Blues
              rgb(178, 223, 138, maxColorValue = 255),
              rgb(51 , 160,  44, maxColorValue = 255), # Greens
              rgb(251, 154, 153, maxColorValue = 255),
              rgb(227,  26,  28, maxColorValue = 255), # Reds
              rgb(253, 191, 111, maxColorValue = 255),
              rgb(255, 127,   0, maxColorValue = 255), # Oranges
              rgb(202, 178, 214, maxColorValue = 255),
              rgb(106,  61, 154, maxColorValue = 255)) # Purples

blues   <- c('dodgerblue2', 'deepskyblue2', 'cornflowerblue',
             'dodgerblue3', 'dodgerblue4', 'darkblue')

reds    <- c('tomato2', 'indianred2', 'coral')

purples <- c('slateblue2', 'violetred2')

greens  <- c('yellowgreen', 'chartreuse3')

Create range of colors

my_palette <- colorRampPalette(c('white', 'blue'))
my_palette(10)

##  [1] "#FFFFFF" "#E2E2FF" "#C6C6FF" "#AAAAFF" "#8D8DFF" "#7171FF" "#5555FF"
##  [8] "#3838FF" "#1C1CFF" "#0000FF"

Mimic ggplot2 colors

Function from John Colby on stack overflow

gg_color_hue <- function(n) {
  hues = seq(15, 375, length = n + 1)
  hcl(h = hues, l = 65, c = 100)[1:n]
}

# The following will return the red and green of ggplot2
gg_color_hue(2)

## [1] "#F8766D" "#00BFC4"