Appendix C — Theme

Every chapter in this book has its own late 90s ggplot2 theme to match its simulated data (Game Boy greens for Alleyway, silver comic book cans for OK Soda, and so on). The themes and the small helpers the book uses live in the fmggp2 package, so every chapter loads the same tested code.

C.1 Installing fmggp2

Install the development version of fmggp2 from GitHub:

# install.packages("pak")
pak::pak("mjfrigaard/fmggp2")

C.2 Using a theme

Each chapter sets its theme once in the setup chunk with ggplot2::theme_set(), so every graph in the chapter picks it up and we don’t have to add the theme to each plot:

ggplot2::theme_set(fmggp2::theme_gameboy(base_size = 14))

We can also add a theme to a single graph like any other ggplot2 theme. Below we simulate a few home PCs from 1998 and add theme_netscape():

set.seed(1998)
home_pcs <- tibble(mhz = runif(60, min = 200, max = 450)) |>
  mutate(price = 600 + 3 * mhz + rnorm(60, mean = 0, sd = 150))
ggplot(home_pcs, aes(x = mhz, y = price)) +
  geom_point() +
  labs(title = "Home PCs in 1998", caption = "Simulated data",
       x = "Processor speed (MHz)", y = "Price (USD)") +
  fmggp2::theme_netscape(base_size = 14)

C.3 What the themes set

The 90s themes are built on ggplot2::theme_bw() and use features from ggplot2 4.0, so a single theme can control much more than the background and fonts:

• Colors: the plot background, the frame around the plot, the panel, and the grid lines all come from a palette sampled from the 90s reference.

• Fonts: most themes pair Arial body text with a title display font that fits the reference (Impact for Blockbuster, Gill Sans for NetWare, Comic Sans for GeoCities).

• Discrete palettes: palette.fill.discrete and palette.colour.discrete set the colors for categorical variables, so mapping a variable to fill or color uses the theme’s colors automatically.

• Continuous palettes: four themes (theme_freshprince(), theme_bopit(), theme_geocities(), and theme_surge()) also set palette.fill.continuous, which colors heatmaps, 2D histograms, and hexagon bins.

• Default geoms: element_geom() sets the default fill, colour, and font for layers like geom_bar() and geom_point(), so a graph with no color mapping still matches the theme.

TipOrdered factors

Ordered factors use the viridis scale by default, which overrides the theme’s discrete palette. If a graph doesn’t pick up the theme colors, check whether the variable mapped to fill or color is an ordered factor (for example, the output of lubridate::wday(label = TRUE)). If it is, convert it with factor(x, ordered = FALSE).

C.4 Fonts

The display fonts are system fonts that ship with macOS. Each theme registers its fonts with sysfonts::font_add(). When a font file can’t be found (on Linux or Windows, for example), the theme falls back to "sans" so the graphs still render. You can also pass any font family you’ve registered yourself:

fmggp2::theme_oksoda(base_family = "sans", title_family = "sans")
fmggp2::theme_batman(base_family = "sans", title_family = "sans")

The showtext package draws the registered fonts in the graphs, so each chapter calls showtext::showtext_auto() in its setup chunk. The themes vignette lists every theme’s fonts.

C.5 Themes by chapter

The tables below list the theme used in each chapter and the 90s reference it’s built from.

C.5.1 Univariate

Chapter	Theme	Reference
Bar graphs	theme_gameboy()	Original Game Boy screen
Histograms	theme_oksoda()	OK Soda cans
Frequency polygons	theme_talkboy()	Talkboy cassette recorder
Dot plots	theme_blockbuster()	Blockbuster Video
Density plots	theme_wired()	WIRED magazine
Violin plots	theme_microdrive()	IBM Microdrive
Box plots	theme_n64()	Nintendo 64

C.5.2 Amounts

Chapter	Theme	Reference
Grouped bar graphs	theme_jurassic()	Jurassic Park (1993)
Summary bar graphs	theme_happymeal()	McDonald’s Happy Meal box
Overlapping bar graphs	theme_netware()	Novell NetWare
Heatmaps	theme_freshprince()	The Fresh Prince of Bel-Air
Waffle charts	theme_pogs()	Pogs milk caps
Cleveland dot plots	theme_walkman()	Sony Walkman Sports

C.5.3 Proportions

Chapter	Theme	Reference
Diverging bar graphs	theme_orbitz()	Orbitz drink
Stacked densities	theme_netscape()	Netscape Navigator
Mosaic plots	theme_titanic()	Titanic (1997)
Pie charts	theme_koosh()	Koosh ball
Treemaps	theme_j2me()	J2ME phone games

C.5.4 Distributions

Chapter	Theme	Reference
Overlapping histograms	theme_tamagotchi()	Tamagotchi
Overlapping frequency polygons	theme_supersoaker()	Super Soaker
Overlapping dot plots	theme_goosebumps()	Goosebumps books
Beeswarm plots	theme_tetris()	Tetris
Overlapping density plot	theme_pager()	Two way pagers
Ridgeline plots	theme_squeezit()	Squeezit drinks
Grouped box plots	theme_oregontrail()	The Oregon Trail
Grouped violin plots	theme_aim()	AOL Instant Messenger
Raincloud plots	theme_rzone()	Tiger R-Zone

C.5.5 Dates & times

Chapter	Theme	Reference
Line graphs	theme_batman()	Batman (1989)
Grouped line graphs	theme_snick()	SNICK
Bump charts	theme_visor()	Handspring Visor
Slope graphs	theme_savedbythebell()	Saved by the Bell
Stream plots	theme_hypercolor()	Hypercolor
Alluvial charts	theme_y2k()	Y2K
Instance chart	theme_gushers()	Fruit Gushers

C.5.6 Relationships

Chapter	Theme	Reference
Scatter plots	theme_doom()	Doom
Grouped scatter plots	theme_consolewars()	Console wars
Bubble charts	theme_seinfeld()	Seinfeld
Grouped bubble graph	theme_powerrangers()	Power Rangers
Parallel sets	theme_cuseeme()	CU-SeeMe
Density contours	theme_bopit()	Bop It
2D histograms	theme_geocities()	GeoCities
Hexagon bins	theme_surge()	Surge

C.6 The original book theme

The pages outside the chapters (like this appendix) use fmggp2::theme_fmggp2(), the original custom theme for this book. It combines elements from ggplot2::theme_minimal() and ggplot2::theme_void() with the Ubuntu font, thin light gray grid lines, and no axis ticks. You can view the source code here.