Week 1: Discussion Section - Answer Key

Making maps with tmap and beyond

Author

Alessandra Vidal Meza

Published

September 27, 2024

Create a Map of Easter Island with tmap

tm_shape(ei_elev) +
  tm_raster(style = "cont",
            palette = "-RdYlGn",
            title = "Elevation (m asl)") +
  tm_shape(ei_borders) + 
  tm_borders() +
  tm_shape(ei_roads) + 
  tm_lines(lwd = "strokelwd", 
           legend.lwd.show = FALSE) +
  tm_shape(volcanoes) +
  tm_symbols(shape = 24, 
             size = "elevation",
             title.size = "Volcanoes (m asl)") +
  tm_layout(main.title = "Easter Island",
            bg.color = "lightblue") +
  tm_scale_bar(position = c("left", "bottom")) +
  tm_compass(show.labels = 1)

Create an Interactive Map of Easter Island with tmap

ei_map <- tm_shape(ei_elev) +
  tm_raster(style = "cont",
            palette = "-RdYlGn",
            title = "Elevation (m asl)") +
  tm_shape(ei_borders) + 
  tm_borders() +
  tm_shape(ei_roads) + 
  tm_lines(lwd = "strokelwd", 
           legend.lwd.show = FALSE) +
  tm_shape(volcanoes) +
  tm_symbols(shape = 24, 
             size = "elevation",
             title.size = "Volcanoes (m asl)") +
  tm_layout(main.title = "Easter Island",
            bg.color = "lightblue") +
  tm_scale_bar(position = c("left", "bottom")) +
  tm_compass(show.labels = 1)

tmap_mode("view")
ei_map

Create a Map of Easter Island with ggplot2

#| message: false
#| warning: false
#| eval: false

volcanoes_point <- volcanoes %>%
  mutate(lon = unlist(map(volcanoes$geom,1)),
         lat = unlist(map(volcanoes$geom,2)))

ggplot() +
  geom_sf(data = ei_borders, color = "#212529") +
  geom_stars(data = ei_elev) +
  scale_fill_distiller(name = "Elevation (m asl)",
                       palette = "RdYlGn", na.value = "transparent") +
  geom_sf(data = ei_roads, color = "#343a40") +
  geom_point(data = volcanoes_point, 
             aes(x = lon, y = lat, size = elevation), 
             shape = 17, color = "#22577a") +
  scale_size_continuous(name = "Volcanoes (m asl)") +
  ggspatial::annotation_north_arrow(location = "tr", which_north = "true") +
  ggspatial::annotation_scale(location = "br", width_hint = 0.5) +
  labs(title = "Easter Island") +
  theme_minimal()