sfReapportion-20e.r

library(dplyr)
library(ggplot2)
library(sf)
library(sfReapportion)
library(patchwork)

# spatial points of voter addresses in Paris 20th district
data(Paris20eAddresses)

data(ParisPollingStations2012)
data(ParisIris)
data(RP_2011_CS8_Paris)

# subset geometry of polling stations (new geom, 76 polling stations)
ParisPollingStations2012 <- sf::st_as_sf(ParisPollingStations2012) %>%
  dplyr::filter(arrondisse %in% c(20)) %>%
  dplyr::mutate(id_brut_bv_reu = paste("75020_", num_bv))

# subset geometry of census tracts (old geom, 356 polygons)
# will throw a warning about polygons expected to be spatially constant
ParisIris <- sf::st_as_sf(ParisIris) %>%
  sf::st_intersection(ParisPollingStations2012)

# this is what we're reapportioning
p1 <- ggplot(ParisIris) +
  geom_sf(color = "steelblue") +
  geom_sf(data = ParisPollingStations2012, color = "tomato", fill = NA) +
  scale_size_area(max_size = 10) +
  theme_void()

p2 <- ggplot(ParisIris) +
  geom_sf(color = "steelblue") +
  geom_sf(data = ParisPollingStations2012, color = "tomato", fill = NA) +
  geom_sf(data = Paris20eAddresses, aes(size = nb_adresses), alpha = 1/4) +
  scale_size_area(max_size = 10) +
  theme_void()

ggsave("sfReapportion-20e.png", p1 + p2, width = 10, height = 8)

# subset census data to reapportion (93 distinct census tracts)
RP_2011_CS8_Paris <- dplyr::filter(RP_2011_CS8_Paris,
                                   IRIS %in% ParisIris$DCOMIRIS)

# unweighted
r1 <- sfReapportion(ParisIris, ParisPollingStations2012, RP_2011_CS8_Paris,
                    "DCOMIRIS", "ID", "IRIS")

# weighted
# will throw a warning about `weight_matrix` having only been lightly tested
r2 <- sfReapportion(ParisIris, ParisPollingStations2012,
                    RP_2011_CS8_Paris,
                    "DCOMIRIS", "ID", "IRIS",
                    weight_matrix = Paris20eAddresses,
                    weight_matrix_var = "nb_adresses")

r1 <- ggplot(left_join(ParisPollingStations2012, r1, by = "ID")) +
  geom_sf(color = "grey90", aes(fill = C11_POP15P_CS7)) +
  scale_fill_viridis_c("CS7") +
  theme_void() +
  labs(title = "Weighted by area")

r2 <- ggplot(left_join(ParisPollingStations2012, r2, by = "ID")) +
  geom_sf(color = "grey90", aes(fill = C11_POP15P_CS7)) +
  scale_fill_viridis_c("CS7") +
  theme_void() +
  labs(title = "Weighted by area + addresses")

ggsave("sfReapportion-20e-results.png", r1 + r2, width = 10, height = 8)