#30DayMapChallenge 2021 - Day 28 - The Earth is not flat

adams.R

# Draw a world map with an AdamsII projection
# For #30DayMapChallenge 2021 - Day 28 - The Earth is not flat
#   -- David Friggens, November 2021

library(sf)
library(dplyr)
library(ggplot2)
library(rnaturalearth)
library(ggtext)

adams2 <- "+proj=adams_ws2"

world_medium <-
  ne_countries(scale = "medium", returnclass = "sf")

adams_world <- 
  world_medium %>%
  st_transform(crs = adams2)

adams_bbox <- 
  adams_world %>% 
  st_bbox()

adams_diamond <- 
  list(
    cbind(
      c(-180, -180, 180, 180, 180, -180, -180),
      c(0, 90, 90, 0, -89.9, -89.9, 0)
    )
  ) %>% 
  st_polygon() %>% 
  st_sfc(crs = 4326L) %>% 
  st_transform(crs = adams2)

adams_bbox <- adams_diamond %>% st_bbox()
xn <- adams_bbox["xmin"]; xx <- adams_bbox["xmax"]; yn <- adams_bbox["ymin"]; yx <- adams_bbox["ymax"];
cx_lo <- (xx + -xn) * .25 + xn
cx_hi <- (xx + -xn) * .75 + xn
cy_lo <- (yx + -yn) * .19 + yn
cy_hi <- (yx + -yn) * .74 + yn

plot_labels <- 
  tribble(
    ~x, ~y, ~label_angle, ~label_size, ~label_text,
    cx_lo, cy_hi, 45, 36, "The World is a Flat Square",
    cx_hi, cy_hi, -45, 20, "#30DayMapChallenge 2021 - Day 28 - The Earth is not flat",
    cx_lo, cy_lo, 135, 20, "Projection: Adams World in a Square II",
    cx_hi, cy_lo, -135, 20, "Map by David Friggens @dakvid"
  ) %>% 
  st_as_sf(coords = c("x", "y"),
           crs = adams2)

gg_adams <- 
  ggplot() +
  geom_sf(data = adams_diamond,
          fill = "dark blue") +
  geom_sf(data = adams_world,
          fill = "dark green", color = NA) +
  geom_richtext(data = plot_labels,
                stat = "sf_coordinates",
                family = "High Alpine",
                aes(geometry = geometry,
                    label = label_text,
                    angle = label_angle,
                    size = label_size),
                vjust = 0,
                fill = NA, label.colour = NA) +
  scale_size_identity() +
  theme_void() +
  theme(plot.background = element_rect(fill = "white", colour = NA),
        panel.background = element_rect(fill = "white", colour = NA),
        legend.position = "none")

ggsave(plot = gg_adams,
       "Day_28/Day_28_adams_square.png",
       width = 24, height = 24, dpi = 72)