Bold the first line of strings that are assigned to y-axis text in ggplot2 in r-CodePudding

Considering the followinf dataframes as an example

DF1 <- data.frame(A = c(1, 2, 3), B = c("a", "b", "c"))
DF2 <- data.frame(Y = paste0("this is the first line thats bold ", DF1$A, "\n",
                            "this is the second line thats plain ", DF1$B),
                 X = structure(c(18903, 18965, 19081), class = "Date"))

DF2 looks like this:

> DF2
                                                                           Y          X
1 this is the first line thats bold 1\nthis is the second line thats plain a 2021-10-03
2 this is the first line thats bold 2\nthis is the second line thats plain b 2021-12-04
3 this is the first line thats bold 3\nthis is the second line thats plain c 2022-03-30

Now if I create a simple scatter plot of this data:

ggplot(DF2, aes(x = X, y = Y))   geom_point()

How can I make the first line of the y-axis text bold? so I want the this is the first line thats bold 1(2,3) be bold and the this is the second line thats plain A(B,C) to remain plain.

CodePudding user response：

ggtext package allows to format axis text as Markdown:

library(ggtext)
library(tidyverse)

DF1 <- data.frame(A = c(1, 2, 3), B = c("a", "b", "c"))
DF2 <- data.frame(
  Y = paste0(
    "this is the first line thats bold ", DF1$A, "\n",
    "this is the second line thats plain ", DF1$B
  ),
  X = structure(c(18903, 18965, 19081), class = "Date")
)


DF2 %>%
  mutate(Y = Y %>% str_replace("^", "**") %>% str_replace("\n", "**\n\n")) %>%
  ggplot(aes(x = X, y = Y))  
  geom_point()  
  theme(axis.text.y = element_markdown())

^{Created on 2022-04-27 by the reprex package (v2.0.0)}