Applying CMAP color schemes • cmapplot

There are 31 color palettes in the cmapplot package, across three categories: discrete, sequential, and divergent. Mirroring the underlying functionality of ggplot2, cmapplot can apply these color palettes as either discrete or continuous scales to either the color (outline) or fill attributes of a ggplot.

This table lists all palettes currently available in the package:

Discrete	Sequential	Sequential (multi-hue)	Divergent
prosperity	reds	yellow_orange_red	yellow_purple
community	oranges	green_teal_blue	orange_blue
environment	yellows	orange_red	red_teal
governance	greens	yellow_orange	purple_green
mobility	teals	yellow_green	blue_yellow
legislation	blues	green_teal	teal_orange
friday	purples	teal_blue	green_red
race	grays	red_purple

Using CMAP color palettes in plots

Discrete scales

Discrete color scales are used to assign colors to discrete bins, such as the lines in a time series line chart. Discrete scale functions work with any palette – discrete, sequential, or divergent. Add a discrete color scale by calling either the cmap_fill_discrete() or cmap_color_discrete() function in your plot construction.

Note that discrete scales will automatically interpolate additional colors if the dataset has more colors than the underlying palette. This can be helpful but is not ideal for finished graphics.

df <- dplyr::filter(grp_over_time, category == "Goods-Producing")

ggplot(data = df) +
  geom_line(mapping = aes(x = year, y = realgrp, color = cluster), 
            size = 1.25) +
  scale_x_continuous(breaks = seq(from = 2007, to = 2017, by = 2)) +
  cmap_color_discrete(palette = "community", reverse = TRUE) +
  theme_cmap() +
  ggtitle("Real GRP of goods-producing clusters over time")
#> Warning: Using `size` aesthetic for lines was deprecated in ggplot2 3.4.0.
#> ℹ Please use `linewidth` instead.
#> This warning is displayed once every 8 hours.
#> Call `lifecycle::last_lifecycle_warnings()` to see where this warning was
#> generated.

Race/ethnicity scale

In order to maintain a consistent data language, CMAP uses specific colors for displaying data based on race and ethnicity. To map these colors to each demographic group, use cmap_fill_race() or cmap_color_race().

In the arguments, specify the case-sensitive name of each group as it appears in your data. The functions can be used even if your dataset does not contain every race/ethnicity category — simply omit the parameters for the missing categories. Likewise, if your dataset already contains the default race/ethnicity categories (case-sensitive) specified in the race palette, no arguments have to be provided.

df <- dplyr::filter(
  traded_emp_by_race,
  Race != "Regional average" & variable == "SpecializedTraded"
)

ggplot(data = df) +
  geom_col(mapping = aes(x = Race, y = value, fill = Race)) +
  scale_y_continuous(labels = scales::label_percent(accuracy = 1)) +
  cmap_fill_race(white = "White",
                 black = "Black",
                 hispanic = "Hispanic",
                 asian = "Asian",
                 other = "Other") +
  theme_cmap(show.legend = FALSE) +  # Legend is redundant in this example
  ggtitle("Percent employed in specialized traded clusters, by race")

Continuous scales

Continuous color scales work with sequential and divergent palettes. Add a continuous scale by calling either the cmap_fill_continuous() or cmap_color_continuous() function in your plot construction. If you’re using a divergent palette, you can specify the midpoint where the divergence begins (default is zero).

df <- dplyr::filter(
  percentile_wages,
  cluster %in% c("Biopharmaceuticals", "Hospitality and Tourism", "Paper and Packaging")
)

ggplot(data = df) +
  geom_point(mapping = aes(x = cluster, y = wage, color = percentile),
             size = 5) +
  scale_y_continuous(labels = scales::dollar) +
  scale_x_discrete(labels = scales::label_wrap(18)) +
  coord_flip() +
  cmap_color_continuous(palette = "red_teal", middle = 50) +
  theme_cmap() +
  ggtitle("Wage percentiles for key clusters")

Highlighting categories

If you want to draw attention to a specific group in your graph, use cmap_fill_highlight() or cmap_color_highlight(). This will make your highlighted group one color and all other groups identical in another color. Specify the vector in your data that determines the groups, and then the value of the group to be singled out. Note that this must be the same vector specified in the fill/color aesthetic. The highlight and non-highlight colors have defaults, but can be changed with the color_value and color_other parameters, respectively.

More than one category can be highlighted as well, by feeding a vector of values into the the value argument. See ?cmap_fill_highlight for details.

df <- dplyr::filter(transit_ridership, year == 2019)

ggplot(data = df) +
  geom_col(mapping = aes(x = system, y = ridership, fill = system)) +
  cmap_fill_highlight(field = transit_ridership$system,
                      value = "metra") +
  theme_cmap(show.legend = FALSE) +  # Legend is redundant in this example
  ggtitle("Annual passenger trips by service, in millions")

Available color palettes

Palettes are stored in a tibble in the cmapplot_globals environment. This tibble can be accessed with get_cmapplot_global("palettes"), with specific details about any specific palette most easily accessed with fetch_pal(). Palettes can be visualized in the plot window with viz_palette() and viz_gradient().

Discrete palettes

Use these palettes with cmap_fill_discrete() or cmap_color_discrete():

The race palette is a special discrete palette, which should be used with the specific functions cmap_fill_race() or cmap_color_race():

Sequential palettes

Use these palettes with cmap_fill_continuous()/cmap_color_continuous() or cmap_fill_discrete()/cmap_color_discrete().

If you use a sequential palette for a discrete scale, the package will automatically choose colors from across the selected gradient and interpolate additional ones if needed. For example, the blues palette is shown below, interpolating nine colors from the initial palette list of seven.

Divergent palettes

Use these palettes with cmap_fill_continuous()/cmap_color_continuous() or cmap_fill_discrete()/cmap_color_discrete(). Using these palettes for a discrete scale will behave similarly to the discrete use of blues shown above.