density plot

R code of the ggplot2 example

library(ggplot2)
library(dplyr)
library(palmerpenguins)

flippers <- penguins |>
  filter(!is.na(flipper_length_mm))

peaks <- flippers |>
  group_by(species) |>
  summarise(d = list(density(flipper_length_mm))) |>
  mutate(x = sapply(d, \(d) d$x[which.max(d$y)]),
         ## Moved right, off the Adelie curve.
         x = x + ifelse(species == "Chinstrap", 4, 0),
         y = sapply(d, \(d) max(d$y)))

p <- ggplot(flippers, aes(x = flipper_length_mm, colour = species, fill = species)) +
  geom_density(alpha = 0.25, linewidth = 0.6) +
  geom_text(data = peaks, aes(x = x, y = y, label = species), vjust = -0.6, size = 3.5) +
  scale_x_continuous(labels = lex_number, breaks = lex_break_breaks, expand = lex_break_expand) +
  scale_y_continuous(expand = expansion(mult = c(0, 0.12))) +
  labs(title = "Gentoo penguins have the longest flippers",
       x = "Flipper length (mm)", y = "Density",
       caption = "Data: palmerpenguins (Horst, Hill & Gorman 2020)") +
  theme_lex_viz(grid = "x", break_not_zero = "x") +
  theme(legend.position = "none")