Make a stained glass heart with ggplot

stained_glass_heart.R

# inpired by https://github.com/IcaroBernardes/30DayChartChallenge/blob/master/2022/day10/day10.R

library(ggplot2)
library(dplyr)
library(sf)
library(ggforce) # for voroni tiles

seed <- 8675309
n_pts <- 150 ### Number of points to try to put inside the window
palette <- c(
  "pink" = "#983E82",
  "orange" = "#E2A458",
  "yellow" = "#F5DC70",
  "green" = "#59935B",
  "blue" = "#467AAC",
  "purple" = "#61589C"
)

# make heart frame
t <- seq(0, 2*pi, by=0.05) %>% c(0)
frame <- cbind(
  16*sin(t)^3,
  13*cos(t)-5*cos(2*t)-2*cos(3*t)-cos(4*t)
)

# convert to a polygon
frame_sf <- frame %>%
  list() %>% 
  sf::st_polygon()

## Create random data points in frame bounds
set.seed(seed)
points <- tibble(
  x = runif(n_pts, min = min(frame[,1]), max = max(frame[,1])),
  y = runif(n_pts, min = min(frame[,2]), max = max(frame[,2]))
)

## Creates a new sf object to hold the created points
points_sf <- sf::st_as_sf(points, coords = c("x","y"))

## Keeps only the random points that are within the frame
contained <- sf::st_contains(frame_sf, points_sf)
points <- points %>% dplyr::slice(contained[[1]])


## Applies random colors and alphas to the remaining points
set.seed(seed)
points <- points %>% 
  mutate(
    fill = sample(palette, nrow(.), T),
    alpha = runif(nrow(.), min = 0.2, max = 0.9)
  )


ggplot(points) +
  geom_voronoi_tile(aes(x = x, y = y, 
                        group = -1L, 
                        fill = I(fill),
                        alpha = I(alpha)),
                    color = "black", 
                    size = 1.5, 
                    bound = frame) +
  geom_sf(data = frame_sf, 
          size = 4, 
          color = "black", 
          fill = "transparent") +
  theme_void()

ggsave("stained_glass_heart.png", width = 4, height = 4)