Convert latitude and longitude to county fips code and create a leaflet map

lat_lng_to_fips.txt

# Convert latitude and longitude to county FIPS code from a survey and create a leaflet map

# Load your survey and define the lat/long variables as numeric
survey <- tibble::tribble(
  ~Latitude, ~Longitude, ~Name,
  44.617000, -92.556600, "<b>Hagar City, WI</b> </br> Trenton Bluff Prairie </br> Ridge Soaring </br> S to SW </br> P2",
  43.256443, -89.789153, "<b>Sauk City, WI</b>  </br> Towing </br> E or W </br> P2",
  43.036036, -89.502803, "<b>Madison, WI</b>  </br> Elver Park </br> Training Hill </br> NNE to NNW </br> P1",
  44.9369, -91.3929, "<b>Chippewa Falls, WI</b> </br> Home"
)

survey$Latitude <- as.numeric(survey$Latitude)
survey$Longitude <- as.numeric(survey$Longitude)

# Define a function to use lat/long variables to get the FIPS code data from the FCC's census using JSON
geo2fips <- function(latitude, longitude) { 
  res <- jsonlite::fromJSON(sprintf("https://geo.fcc.gov/api/census/area?lat=%f&lon=%f&format=json", 
                                    latitude, longitude))[["results"]][["county_fips"]]
  unique(res)
}

# Apply the function to each row of the dataframe (this may take awhile if you have a large dataset)
survey$fips <- mapply(geo2fips, survey$Latitude, survey$Longitude)

# Create the leaflet map with the county polgygons, population percentiles, and location markers
tracts <- tigris::tracts(state = 'WI', cb=TRUE)

fetched <- tidycensus::get_acs(geography = "county", 
                               variables = "B01003_001", 
                               state = "WI",
                               geometry = TRUE,
                               key = "XXX") # Insert your API key here (https://api.census.gov/data/key_signup.html)

pal <- leaflet::colorQuantile(palette = "viridis", domain = fetched$estimate, n = 5)

fetched %>%
  sf::st_transform(crs = "+init=epsg:4326") %>%
  leaflet::leaflet(width = "100%") %>%
  leaflet::addProviderTiles(provider = "CartoDB.Positron") %>%
  leaflet::addProviderTiles(leaflet::providers$OpenTopoMap, group='Topo') %>%
  leaflet::addPolygons(popup = ~ stringr::str_extract(NAME, "^([^,]*)"),
                       stroke = FALSE,
                       smoothFactor = 0,
                       fillOpacity = 0.4,
                       color = ~ pal(estimate)) %>%
  leaflet::addLegend("bottomright", 
                     pal = pal, 
                     values = ~ estimate,
                     title = "Population percentiles",
                     opacity = 1) %>%  # Add default OpenStreetMap map tiles
  leaflet::addMarkers(lng = survey$Longitude, lat = survey$Latitude, popup = survey$Name)