Color recipes


2020 12 18


This vignette shows how various color-related tasks can be solved by the tools provided by unikn. (For a general introduction of the unikn colors, color palettes, and color functions, see the vignette on Colors and color functions. The vignette on text provides information on creating text boxes and decorations.)

The following recipes illustrate how plotting functions in R can use the colors and color palettes provided by the unikn package. Additional examples show how we can use the seecol(), usecol(), newpal(), and grepal() functions for solving color-related tasks.

Please install and/or load the unikn package to get started:

# install.packages('unikn')  # install unikn from CRAN client
library('unikn')             # loads the package

Using colors in base R

Task: Using unikn colors in visualizations created by base R graphics.

When creating base R visualizations (e.g., using plot() for creating a scatterplot), use the usecol() function in combination with any color palette (e.g., pal_unikn) as the col argument:

my_col <- usecol(pal_unikn, alpha = .50)  # with transparency

plot(x = runif(99), y = runif(99), type = "p", 
     pch = 16, cex = 4,
     col = my_col,
     main = "99 transparent dots", axes = FALSE, xlab = NA, ylab = NA)

Using colors in ggplot2

Task: Using unikn colors in visualizations created by the ggplot2 package.

When using the ggplot() function of ggplot2 (e.g., for creating an area plot), use the usecol() function for defining a color palette (of the desired length and transparency) that is then provided as the values of the scale_color_manual() or scale_fill_manual() functions:

  1. Use the usecol() function of unikn to define a color palette.

  2. Provide this palette as the values of the ggplot2 functions scale_color_manual() or scale_fill_manual().

# 0. Data: ---- 
# Example based on 
n <- 50
names <- paste("G_", seq(1, n), sep = "")
df <- data.frame()

for (i in seq(1:30)){
    data <- data.frame(matrix(0, n, 3))
    data[, 1] <- i
    data[, 2] <- sample(names, nrow(data))
    data[, 3] <- prop.table(sample( c(rep(0, 100), c(1:n)), nrow(data)))
    df <- rbind(df, data)}
colnames(df) <- c("X","group","Y")
df <- df[order(df$X, df$group) , ]

# 1. Colors: ---- 
# A. using RColorBrewer: 
# library(RColorBrewer)

# cur_col <- brewer.pal(11, "Paired") 
# cur_col <- colorRampPalette(cur_col)(n)
# cur_col <- cur_col[sample(c(1:length(cur_col)), size = length(cur_col))]  # randomize

# B. using unikn colors:

cur_col <- usecol(pal = pal_unikn, n = n)
# cur_col <- cur_col[sample(c(1:length(cur_col)), size = length(cur_col))]  # randomize

# 2. Plotting: ---- 


ggplot(df, aes(x = X, y = Y, fill = group)) + 
  geom_area(alpha = 1, color = Grau, size = .01 ) +
  scale_fill_manual(values = cur_col) +
  theme_void() +
  theme(legend.position = "none")


Viewing and comparing color palettes

Task: View (the colors and details of) a color palette.

For easily viewing a new color palette (e.g., provided by the new HCL color palettes hcl.pals() of R), use the palette as the pal argument of the seecol() function:

col_pal <- hcl.colors(10, "Vik")  # some color palette

seecol(col_pal)  # see its colors and details 

Note that the other arguments of the seecol() function — especially n and alpha — can further modify the palette.

Task: Compare (the colors and range of) multiple color palettes.

For comparing multiple color palettes (e.g., 20 random color palettes of hcl.pals()), provide them as a list in the pal argument of the seecol() function.

For instance, let’s create and compare a set of 20 random HCL palettes:

seecol(pal = l_pal, 
       pal_names = s_pal,
       col_brd = "white", lwd_brd = 1,
       title = t_lbl)

Creating new color palettes

Task: Create a new color palette (with color names).

The general steps for creating an new color palette (with dedicated color names) are:

  1. Choose some colors (and their R color names, or as RGB/HEX/HCL values, e.g., from sites like

  2. Define the colors as an R vector (of type character).

  3. Define their names as a second R vector (of type character).

  4. Use the newpal() command to define the new color palette.

  5. Use the seepal() command to inspect the new color palette.

# 1. Choose colors:
# Google logo colors (from <>)

# 2. Define colors (as vector):
color_google <- c("#4285f4", "#34a853", "#fbbc05", "#ea4335")

# 3. Define color names (as vector):
names_google <- c("blueberry", "sea green", "selective yellow", "cinnabar")

# 4. Define color palette:
pal_google <- newpal(color_google, names_google)

# 5. Inspect color palette:
       col_brd = "white", lwd_brd = 8,
       title = "Colors of the Google logo")

The new palette pal_google can now be used in R graphics and modified in various ways (e.g., by the usecol() function).

Finding colors by name

Task: Find colors by matching their names to a pattern (as a regular expression).

Here are some additional examples for using the grepal() function for finding colors by their names (or a pattern):

# Get color palettes matching a pattern:
pal_1 <- grepal("orange")
pal_2 <- grepal("olive")
pal_3 <- grepal("white")

# See individual palettes:
# seecol(pal_1, title = "Shades of 'orange' colors()")
# seecol(pal_2, title = "Shades of 'olive' colors()")
seecol(pal_3, title = "Shades of 'white' colors()", col_bg = "grey90")

Providing a list of color palettes to the pal argument of the seecol() function allows comparing multiple color palettes:

# See multiple color palettes:
seecol(pal = list(pal_1, pal_2, pal_3), 
       pal_names = c("orange", "olive", "white"), 
       col_bg = "grey90")

The last example illustrates that (a) the pattern argument of grepal() can use regular expressions, and that (b) the x argument of grepal() works with vectors or data frames (e.g., the unikn color palettes).

Let’s compare different types of “blue”, “orange”, and “purple or violet” provided by the grDevices vector of named colors() with various shades of “blau”, “pink”, “peach” and “bordeaux” provided by unikn color palettes:

# Search colors() with specific patterns (in their names): 
blues    <- grepal("blue$")   # ending on "blue"
oranges  <- grepal("orange")  # containing "orange"
purpviol <- grepal("purple|violet")  # containing "purple" or "violet"

# Search unikn palettes for color names: 
blaus_1 <- grepal("blau", pal_unikn)
blaus_2 <- grepal("blau", pal_karpfenblau)
pinks <- grepal("pink", pal_pinky)
peach <- grepal("peach", pal_peach)
baux  <- grepal("bordeaux", pal_bordeaux)

# See multiple color palettes: 
seecol(list(blues, oranges, purpviol, 
            c(blaus_1, blaus_2, pinks, peach, baux)),
       pal_names = c("blues", "oranges", "purpviol", "unikn colors"),
       title ="Comparing custom color palettes")


The following versions of unikn and corresponding resources are currently available:

Type: Version: URL:
A. unikn (R package): Release version
  Development version
B. Online documentation: Release version
  Development version


The following vignettes provide instructions and examples for using the unikn colors, color palettes, and functions:


Nr. Vignette Content
1. Colors Colors and color functions
2. Color recipes Recipes for color-related tasks
3. Institutional colors Creating color palettes for other institutions
4. Text Text boxes and decorations