slopegraph

R code of the ggplot2 example

library(ggplot2)
library(dplyr)
library(gapminder)

## Oceania, two countries only, is left out.
life <- gapminder |>
  filter(year %in% c(1952, 2007), continent != "Oceania") |>
  group_by(continent, year) |>
  summarise(lifeExp = mean(lifeExp), .groups = "drop")
start <- filter(life, year == 1952)
end <- filter(life, year == 2007)

## Names in the darker text colors of the continents, readable on white.
p <- ggplot(life, aes(x = factor(year), y = lifeExp, group = continent, colour = continent)) +
  geom_line(linewidth = 0.8) +
  geom_point(size = 2) +
  geom_text(data = start, aes(label = paste(continent, round(lifeExp))),
            colour = continent_text_colors[as.character(start$continent)],
            hjust = 1, nudge_x = -0.08, size = 3.2) +
  geom_text(data = end, aes(label = paste(round(lifeExp), continent)),
            colour = continent_text_colors[as.character(end$continent)],
            hjust = 0, nudge_x = 0.08, size = 3.2) +
  scale_x_discrete(position = "top", expand = expansion(add = 0.9)) +
  scale_y_continuous(NULL, breaks = NULL) +
  scale_colour_manual(values = continent_colors) +
  labs(title = "Asia gained the most life expectancy, Africa still trails",
       subtitle = "Life expectancy in years, mean over the countries of each continent",
       x = NULL,
       caption = "Data: Gapminder, via the gapminder R package") +
  theme_lex_viz(grid = "", arrows = "") +
  theme(legend.position = "none", axis.text.x = element_text(face = "bold"))