Creates a gif of the world in different map projections

map_projections.R

library(tidyverse)
library(sf)
library(spData)
library(gganimate)
data(world)

# see also: https://proj.org/operations/projections/index.html
projs <- list(
  "Mercator" = "+proj=merc",
  "WGS 84" = "+proj=longlat",
  "Robinson" = "+proj=robin",
  "Compact Miller" = "+proj=comill",
  "Eckert I" = "+proj=eck1",
  "Eckert II" = "+proj=eck2",
  "Eckert III" = "+proj=eck3",
  "Eckert IV" = "+proj=eck4",
  "Mollweide" = "+proj=moll", 
  "Azimuth Equidistant" = "+proj=aeqd",
  "Lambert Equal Area" = "+proj=laea",
  "Adams World in a Square 2" = "+proj=adams_ws2",
  "Sinusoidal (Sanson-Flamsteed)" = "+proj=sinu",
  "Interrupted Goode Homolosine" = "+proj=igh"
)

dd <- map_dfr(projs, function(p) {
  d <- world %>% 
    select(iso_a2, name_long, continent, geom) %>% 
    mutate(projection = p, L1 = 1:n()) %>% 
    st_transform(p)
  
  dd <- left_join(
    st_coordinates(d) %>% as_tibble(), 
    d %>% as_tibble() %>% select(-geom), 
    by = "L1"
  )
  
  res <- dd %>% 
    select(x = X, y = Y, everything()) %>% 
    mutate(id = paste0(L1, L2, L3)) %>% 
    mutate(x_orig = x, y_orig = y,
           x = (x - min(x)) / (max(x) - min(x)),
           y = (y - min(y)) / (max(y) - min(y)))
  
  res
}) %>% 
  mutate(projection = factor(projection, levels = unlist(projs)))

anim <- ggplot(dd, aes(x = x, y = y, group = id)) + 
  geom_polygon(fill = "black") +
  transition_states(projection) +
  ease_aes("cubic-in-out") +
  labs(title = "The World in '{names(projs)[projs == closest_state]}' Projektion",
       subtitle = "Projection: '{closest_state}'") +
  theme_minimal() +
  theme(axis.title=element_blank(),
        axis.text=element_blank(),
        axis.ticks=element_blank(), 
        panel.grid=element_blank(),
        plot.background=element_rect(fill = "white"))

anim_save("images/projections.gif", anim, res = 200, width = 1000, height = 1000)

Hi, I just found this while searching. Just noting that it doesn't seem to work.

In the dd section:

Error in CPL_transform(x, crs, aoi, pipeline, reverse) :
crs not found: is it missing?

Then others because that is missing.

Make sure you have the latest PROJ version installed, then it should work

I updated PROJ, but it still didn't work.

I got this message:

PROJ is currently non-operational since version 0.4.0

Sorry that I wasn't more clear. I meant the software PROJ and not the r package. See also https://proj.org/index.html

Thanks. I'll give it a go.