horizon chart

R code of the ggplot2 example

library(ggplot2)
library(dplyr)
library(tidyr)
library(HistData)

## Each series cut into bands of 200 deaths a day, laid on top of each
## other: the darker the band, the higher the count.
band <- 200
bands <- CholeraDeaths1849 |>
  select(date, cause_of_death, deaths) |>
  expand_grid(level = 1:6) |>
  mutate(height = pmin(pmax(deaths - (level - 1) * band, 0), band)) |>
  filter(level <= ceiling(max(deaths) / band))

p <- ggplot(bands, aes(x = date, ymin = 0, ymax = height, fill = factor(level))) +
  geom_ribbon() +
  facet_wrap(~cause_of_death, ncol = 1, strip.position = "left") +
  scale_fill_manual(values = idest_seq) +
  scale_x_date(date_breaks = "2 months", labels = scales::label_date("%b", locale = "en"),
               expand = c(0, 0)) +
  scale_y_continuous("Deaths a day, within a band", breaks = c(0, 100, 200), expand = c(0, 0)) +
  labs(title = "Cholera deaths peaked on September 6, 1849",
       subtitle = "Daily deaths in England; each darker band adds 200 deaths a day; peaks: cholera 1\u2009121 on September 6, diarrhea 218 on September 10",
       x = NULL,
       caption = "Data: Farr 1852, via the HistData R package") +
  theme_lex_viz(grid = "", arrows = "") +
  theme(legend.position = "none", panel.spacing = unit(4, "mm"))