Author: SPDS, uni.kn

# Color recipes

#### SPDS, uni.kn

#### 2022 11 30

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. Wrap the desired color palette in the `usecol()` function of unikn.

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

    # 0. Create data: ----

    # Example based on https://www.r-graph-gallery.com/137-spring-shapes-data-art/
    n <- 50
    groups <- 1:n
    df <- data.frame()

    set.seed(3)

    for (i in seq(1:30)){
      data = data.frame(matrix(0, n, 3))
      data[, 1] <- i
      data[, 2] <- sample(groups, nrow(data))
      data[, 3] <- prop.table(sample(c(rep(0, 100), c(1:n)), nrow(data)))
      df = rbind(df, data)}

    names(df) <- c("X","Group","Y")
    df$Group <- as.factor(df$Group)
    df <- df[c(2, 1, 3)]
    df <- df[order(df$X, df$Group) , ]
    rownames(df) <- NULL

    my_data <- df

    # 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:
    library(unikn)

    # Mix a color gradient:
    cur_col <- usecol(c(Bordeaux, "white", Petrol), n = n)
    # cur_col <- cur_col[sample(c(1:length(cur_col)), size = length(cur_col))]  # randomize

    # 2. Plotting: ----

    library(ggplot2)

    ggplot(my_data, aes(x = X, y = Y, fill = Group)) +
      geom_area() +
      scale_fill_manual(values = cur_col) +
      theme_void() +
      theme(legend.position = "none")

## Viewing and comparing color palettes

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

For easily viewing an individual 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 modify the palette (in the same ways as the `usecol()` function).

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:

- Generate random HCL palettes (and save them as a list):

    # Parameters:
    n_col <-  8   # colors in each palette
    n_pal <- 20   # length(hcl.pals())
    ptype <- NULL # c("diverging", "divergingx", "qualitative", "sequential")[4]

    s_pal <- sample(x = hcl.pals(type = ptype), size = n_pal, replace = FALSE)
    s_pal <- sort(s_pal)

    # Initialize:
    t_lbl <- paste0("See ", n_pal, " random HCL color palettes (n = ", n_col, ")")
    l_pal <- vector("list", n_pal)  # lists of palettes

    # Loop:
    for (i in 1:n_pal){

      l_pal[[i]] <- hcl.colors(n = n_col, palette = s_pal[i])

    }

- Use `seecol()` for comparing multiple color palettes:

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

## Finding similar colors

Task: Find a color that is similar to some given color.

Use the `simcol()` function for finding (and plotting/seeing) similar colors:

    simcol("forestgreen")
    #>    forestgreen    chartreuse4         green4      olivedrab     olivedrab4
    #>  "forestgreen"  "chartreuse4"       "green4"    "olivedrab"   "olivedrab4"
    #>     palegreen4   springgreen4
    #>   "palegreen4" "springgreen4"

The `simcol()` function compares a require target color (`col_target`) with a set of candidate colors (`col_candidates`, set to `colors()` by default). Color similarity is defined in terms of the colors’ pair-wise distances in RGB values. If this distance falls below some tolerance value(s) (`tol`), the corresponding `col_candidates` are shown and returned. Thus, increasing the tolerance value yields a wider range of colors:

    simcol(col_target = "orange", col_candidates = pal_unikn_pref, tol = 150)
    #>    orange     Pinky     Peach    Signal  Bordeaux
    #>  "orange" "#E0607E" "#FEA090" "#EFDC60" "#8E2043"

Specifying a vector of three `tol` values compares RGB dimensions in the order of their rank. This allows for more fine-grained similarity searches:

    simcol(col_target = Seeblau, tol = c(20, 20, 80))
    #>         Seeblau    lightskyblue   lightskyblue2         skyblue        skyblue1
    #>       "#59C7EB"  "lightskyblue" "lightskyblue2"       "skyblue"      "skyblue1"
    #>        skyblue2      steelblue1
    #>      "skyblue2"    "steelblue1"

## 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 https://www.schemecolor.com).

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

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

4. Use the `newpal()` command to define the new color palette (as an R data frame or vector).

Once a new palette has been defined, it can be inspected (with `seecol()`) or further modified and used in visualizations (with `usecol()`):

    # 1. Choose colors:
    # Google logo colors (from <https://www.schemecolor.com/google-logo-colors.php>)

    # 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)

    # Inspect color palette:
    seecol(pal_google,
           col_brd = "white", lwd_brd = 8,
           main = "Colors of the Google logo")

The vignette on Institutional colors provides additional examples for defining color palettes.

## 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", plot = FALSE)
    pal_2 <- grepal("olive", plot = FALSE)
    pal_3 <- grepal("white", plot = FALSE)

    # See individual palettes:
    # seecol(pal_1, main = "Hues of 'orange' colors()")
    # seecol(pal_2, main = "Hues of 'olive' colors()")
    seecol(pal_3, main = "Hues 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$", plot = FALSE)   # ending on "blue"
    oranges  <- grepal("orange", plot = FALSE)  # containing "orange"
    purpviol <- grepal("purple|violet", plot = FALSE)  # containing "purple" or "violet"

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

    # 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"),
           main ="Comparing custom color palettes")

## Getting shades of a color

Task: Get different shades of a specific color.

The `shades_of()` function returns a vector of colors that are shades (i.e., typically lighter or darker versions) of an initial color .

By default, `shades_of(n)` yields `n` shades ranging from `col_1 = "black"` to `col_n = "white` (i.e., `n` shades of grey):

    greys <- shades_of(10)
    seecol(greys, main = "10 shades of grey")

By adjusting `n`, the initial color `col_1`, and/or the final color `col_n`, we can conveniently create simple color ranges:

    seecol(shades_of(4, Seeblau, "black"), main = "4 shades of Seeblau")
    seecol(shades_of(5, "forestgreen"), main = "5 shades of 'forestgreen'")

Using `alpha` in the range \([0; 1]\) allows adjusting the transparency of the color gradient:

    wine_gold <- shades_of(4, Bordeaux, col_n = "gold", alpha = .75)
    seecol(wine_gold, main = "5 transparent shades from Bordeaux to gold")

## Creating color gradients

Task: Creating color gradients.

The `shades_of()` function is merely a convenient wrapper function for the `usecol()` function. Using the `pal` argument of `usecol()` allows defining more complex color gradients (e.g., by specifying more than two colors). For instance, to create a bi-polar (divergent) color palette, we could mix two main colors with “white” and then remove the middle color:

    # Create bi-polar color gradient (and remove 'white' middle color):
    divergent_gradient <- usecol(pal = c("firebrick", "white", "steelblue"), n = 7)[-4]

    seecol(divergent_gradient, main = "A bi-polar color palette")

## Resources

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

Type: | Version: | URL:
--- | --- | ---
A. unikn (R package): | Release version | https://CRAN.R-project.org/package=unikn
| Development version | https://github.com/hneth/unikn/
B. Online documentation: | Release version | https://hneth.github.io/unikn/
| Development version | https://hneth.github.io/unikn/dev/

## Vignettes

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