Densité des Comtés US

comtes_us_2018.csv

creation.R

library(tidyverse)
library(sf)

# 1 - recuperation du shapefile
download.file("https://www2.census.gov/geo/tiger/TIGER2017/COUNTY/tl_2017_us_county.zip", destfile = "tl_2017_us_county.zip")
unzip(zipfile = "tl_2017_us_county.zip")
# 2 - lecture du shapefile
counties <- st_read("tl_2017_us_county.shp", stringsAsFactors = FALSE)
# 3 - recuperation des stats par comté
download.file("https://www2.census.gov/programs-surveys/popest/datasets/2010-2018/counties/asrh/cc-est2018-alldata.csv", destfile = "cc-est2018-alldata.csv")
# 4 - lecture du fichier stat
stats_counties <- read_csv("cc-est2018-alldata.csv")
# 5 - extraction de l'année utile (YEAR 11 = 2018-07-01)
stats_counties <- stats_counties %>%
  filter(YEAR == 11) %>%
  filter(AGEGRP == 0) %>% # Population totale
  select(STATE, COUNTY, TOT_POP)
# 6 - calcul de la surface des comtés et agrégation
counties <- counties %>%
  mutate(area = st_area(.)) %>%
  left_join(stats_counties, by = c("STATEFP" = "STATE", "COUNTYFP" = "COUNTY")) %>%
  mutate(areakm2 = as.numeric(area) / 1E6) %>%# passage de m2 à km2
  mutate(densitekm2 = TOT_POP / areakm2) %>%
  select(STATEFP, COUNTYFP, COUNTYNS, NAME, NAMELSAD, TOT_POP, areakm2, densitekm2)
# 7 - export du tableau
write_csv(st_drop_geometry(counties), path = "comtes_us_2018.csv")