diagramme de Voronoï

Code R de l'exemple ggplot2

library(ggplot2)
library(dplyr)
library(ggforce)
library(HistData)

## Each pump gets the cell of the points closer to it than to any other pump.
pumps <- Snow.pumps |>
  mutate(broad = label == "Broad St")
box <- c(range(c(Snow.deaths$x, Snow.pumps$x)) + c(-0.5, 0.5),
         range(c(Snow.deaths$y, Snow.pumps$y)) + c(-0.5, 0.5))

p <- ggplot(pumps, aes(x = x, y = y)) +
  geom_voronoi_tile(aes(fill = broad, group = -1L), bound = box, colour = "#a6a6a6",
                    linewidth = 0.3) +
  geom_point(data = Snow.deaths, size = 0.5, colour = "#535353") +
  geom_point(shape = 17, size = 2.2, colour = "#9b2367") +
  annotate("segment", x = 12.8, y = 11.73, xend = 16.9, yend = 12.6, colour = "#9b2367",
           linewidth = 0.3) +
  annotate("text", x = 17, y = 12.6, label = "Broad\nStreet\npump", colour = "#9b2367",
           hjust = 0, size = 3, lineheight = 0.9) +
  scale_fill_manual(values = c(`FALSE` = NA, `TRUE` = "#9b236726")) +
  coord_fixed(expand = FALSE) +
  labs(title = "Most deaths fall in the Broad Street cell",
       subtitle = "Soho, 1854: cholera deaths, pumps, straight-line cells",
       caption = "Data: Snow 1855, via the HistData R package") +
  theme_lex_viz(grid = "", arrows = "") +
  theme(legend.position = "none", axis.text = element_blank(), axis.title = element_blank(),
        axis.line = element_blank(), axis.ticks = element_blank(),
        plot.title.position = "plot", plot.caption.position = "plot")