The document discusses how to add formatted text like italics, bold, colors and images to ggplot2 visualizations using the ggtext and gridtext packages. It provides examples of labeling bars and points with formatted text, adding correlation values alongside a scatter plot faceted by species, and controlling font properties and alignments. The key package that enables rich text formatting in plots is gridtext.

1. Spruce up your ggplot2 visualizations
with formatted text
Claus O. Wilke
The University of Texas at Austin
https://wilkelab.org/ggtext
@clauswilke clauswilke

2. A common problem:
Mixing italics and normal text in ggplot

3. https://stackoverflow.com/questions/39282293/r-ggplot2-using-italics-and-non-italics-in-the-same-category-label

4. bactname OTUname name value
Staphylococcaceae OTU 1 Staphylococcaceae (OTU 1) -0.5
Moraxella OTU 2 Moraxella (OTU 2) 0.5
Streptococcus OTU 3 Streptococcus (OTU 3) 2.0
Acinetobacter OTU 4 Acinetobacter (OTU 4) 3.0

5. bactname OTUname name value
Staphylococcaceae OTU 1 Staphylococcaceae (OTU 1) -0.5
Moraxella OTU 2 Moraxella (OTU 2) 0.5
Streptococcus OTU 3 Streptococcus (OTU 3) 2.0
Acinetobacter OTU 4 Acinetobacter (OTU 4) 3.0
data %>%
ggplot(aes(name, value)) +
geom_col() + coord_flip()

6. bactname OTUname name value
Staphylococcaceae OTU 1 Staphylococcaceae (OTU 1) -0.5
Moraxella OTU 2 Moraxella (OTU 2) 0.5
Streptococcus OTU 3 Streptococcus (OTU 3) 2.0
Acinetobacter OTU 4 Acinetobacter (OTU 4) 3.0
data %>%
ggplot(aes(name, value)) +
geom_col() + coord_flip()

7. https://stackoverflow.com/questions/39282293/r-ggplot2-using-italics-and-non-italics-in-the-same-category-label

8. How should we specify formatted text?

9. data %>%
ggplot(aes(name, value)) +
geom_col() + coord_flip() +
ggtitle("species names are *in italics*")

10. data %>%
ggplot(aes(name, value)) +
geom_col() + coord_flip() +
ggtitle("species names are *in italics*")
library(ggtext) # remotes::install_github('wilkelab/ggtext')

11. data %>%
ggplot(aes(name, value)) +
geom_col() + coord_flip() +
ggtitle("species names are *in italics*") +
theme(plot.title = element_markdown())
library(ggtext) # remotes::install_github('wilkelab/ggtext')

12. data %>% mutate(
name = glue("*{bactname}* ({OTUname})") # library(glue)
)

13. data %>% mutate(
name = glue("*{bactname}* ({OTUname})") # library(glue)
)
bactname OTUname name value
Staphylococcaceae OTU 1 *Staphylococcaceae* (OTU 1) -0.5
Moraxella OTU 2 *Moraxella* (OTU 2) 0.5
Streptococcus OTU 3 *Streptococcus* (OTU 3) 2.0
Acinetobacter OTU 4 *Acinetobacter* (OTU 4) 3.0

14. data %>% mutate(
name = glue("*{bactname}* ({OTUname})")
) %>%
ggplot(aes(name, value)) +
geom_col() + coord_flip() +
theme(axis.text.y = element_markdown())

15. Your plots are boring.
Don’t you ever use color?

16. data %>% mutate(
color = c("#009E73", "#D55E00", "#0072B2", "#000000"),
name = glue("<i style='color:{color}'>{bactname}</i> ({OTUname})")
) %>%

17. data %>% mutate(
color = c("#009E73", "#D55E00", "#0072B2", "#000000"),
name = glue("<i style='color:{color}'>{bactname}</i> ({OTUname})")
) %>%
ggplot(aes(name, value, fill = color)) +
geom_col(alpha = 0.5) + coord_flip() +
scale_fill_identity() +
theme(axis.text.y = element_markdown())

18. What else can you do?

19. https://stackoverflow.com/questions/14070953/photo-
alignment-with-graph-in-r/30765590#30765590

20. labels <- c(
Interphase = "<img src='img/interphase.jpg' width='50' /><br>Interphase",
Prophase = "<img src='img/prophase.jpg' width='50' /><br>Prophase",
Metaphase = "<img src='img/metaphase.jpg' width='50' /><br>Metaphase",
Anaphase = "<img src='img/anaphase.jpg' width='50' /><br>Anaphase",
Telophase = "<img src='img/telophase.jpg' width='50' /><br>Telophase"
)
https://stackoverflow.com/questions/14070953/photo-
alignment-with-graph-in-r/30765590#30765590

21. https://stackoverflow.com/questions/14070953/photo-
alignment-with-graph-in-r/30765590#30765590
labels <- c(
Interphase = "<img src='img/interphase.jpg' width='50' /><br>Interphase",
...
)
ggplot(data, aes(phase, value, fill = cat)) +
geom_col(position = "dodge") +
scale_x_discrete(name = NULL, labels = labels) +
theme(axis.text.x = element_markdown(lineheight = 1.2))

22. https://stackoverflow.com/questions/14070953/photo-
alignment-with-graph-in-r/30765590#30765590
labels <- c(
Interphase = "<img src='img/interphase.jpg' width='50' /><br>Interphase",
...
)
ggplot(data, aes(phase, value, fill = cat)) +
geom_col(position = "dodge") +
scale_x_discrete(name = NULL, labels = labels) +
theme(axis.text.x = element_markdown(lineheight = 1.2))

23. Text boxes, backgrounds, and word-wrapping
https://wilkelab.org/ggtext

24. Does this only work for theme elements?

25. ggplot(iris, aes(Sepal.Length, Sepal.Width)) +
geom_point() + geom_smooth(method = "lm") +
facet_wrap(~Species)

26. iris_cor <- iris %>%
group_by(Species) %>%
summarize(r_square = cor(Sepal.Length, Sepal.Width)^2)
iris_cor
#> # A tibble: 3 x 2
#> Species r_square
#> <fct> <dbl>
#> 1 setosa 0.551
#> 2 versicolor 0.277
#> 3 virginica 0.209

27. iris_cor <- iris %>%
group_by(Species) %>%
summarize(r_square = cor(Sepal.Length, Sepal.Width)^2) %>%
mutate(
Sepal.Length = 8,
Sepal.Width = 4.5,
label = glue("*r*² = {round(r_square, 2)}")
)
iris_cor
#> # A tibble: 3 x 5
#> Species r_square Sepal.Length Sepal.Width label
#> <fct> <dbl> <dbl> <dbl> <glue>
#> 1 setosa 0.551 8 4.5 *r*² = 0.55
#> 2 versicolor 0.277 8 4.5 *r*² = 0.28
#> 3 virginica 0.209 8 4.5 *r*² = 0.21

28. ggplot(iris, aes(Sepal.Length, Sepal.Width)) +
geom_point() + geom_smooth(method = "lm") +
geom_richtext(
data = iris_cor, aes(label = label),
hjust = 1, vjust = 1
) +
facet_wrap(~Species)

29. The package that makes it all possible

31. text <- "Some text **in bold.**"
gp <- grid::gpar(
fontfamily = "Comic Sans MS", fontsize = 20, col = "blue"
)
g1 <- grid::textGrob(text, 0.1, 0.7, hjust = 0, gp = gp)
grid::grid.draw(g1)

32. text <- "Some text **in bold.**"
gp <- grid::gpar(
fontfamily = "Comic Sans MS", fontsize = 20, col = "blue"
)
g1 <- grid::textGrob(text, 0.1, 0.7, hjust = 0, gp = gp)
g2 <- gridtext::richtext_grob(text, 0.1, 0.4, hjust = 0, gp = gp)
grid::grid.draw(g1)
grid::grid.draw(g2)

33. https://wilkelab.org/ggtext
https://wilkelab.org/gridtext
@clauswilke
clauswilke