Using geocoding API to translate school address to coordinates

retrieveCoords.R

library(data.table)
library(jsonlite)
library(readxl)
library(curl)
# Get your API from GCP
API_KEY <- '&key=$YOUR_API_KEY'
URL <- 'https://maps.googleapis.com/maps/api/geocode/json?address='
# Data source:
# # Elementary high school: https://data.gov.tw/dataset/6087 
# # Junior high school: https://data.gov.tw/dataset/6088
# # elementary school
types <- rep('character', 7)
elem <- data.table::fread('../../elem_school_2019.csv', colClasses = types)
junior <- data.table::fread('../../junior_school_2019.csv', colClasses = types)
htypes <- rep('character', 8)
high <- data.table::fread('../../senior_school_2019.csv', colClasses = htypes)
high[, `備註` := NULL]
# new data sources
selectedCode <- data.table::fread('../../finalList.csv', 
                                  colClasses = 'character')

je <- rbind(elem, junior, high)
# remove county codes and zipcodes in address
je[, county := gsub('[0-9]|\\[|\\]', '', `縣市名稱`)] 
je[, add := gsub('^\\[[0-9]{1,}\\]', '', `地址`)]
s1_list <- je[ `代碼` %in% selectedCode$V1 ] 

for ( i in 1:dim(s1_list)[1] ){
  print(i)
  res <- fromJSON(paste(URL, s1_list[i, add], API_KEY, sep=''))
  res <- res$results
  lat <- res$geometry$location$lat[1]
  lng <- res$geometry$location$lng[1]
  
  s1_list[i, place_id := res$place_id]
  s1_list[i, latitude := lat ]
  s1_list[i, longitude := lng ]
}

# extract coordinates from school list
listCoor <- s1_list[, .(longitude, latitude)]

colnames(listCoor) <- c('x', 'y')
listCoor_kmeans <- kmeans(listCoor, 10)

s1_list[, group := listCoor_kmeans$cluster ]
data.table::fwrite(s1_list, '../../s1_school_list.csv')

# get schools' polygons
s1_list[, fullnames := paste(gsub('市$|縣$', '', county), `學校名稱`, sep = '')]
s1_list[, fullnames]

# Get school polygons from openstreetmaps
osmSearchURL <- 'https://nominatim.openstreetmap.org/search?q='
osmParameters <- '&format=geojson&polygon_geojson=1'

for ( s in 1:dim(s1_list)[1]) {
  print(paste(s, s1_list[s, fullnames]))
  querySchool <- paste(osmSearchURL, s1_list[s, fullnames], 
                       osmParameters, sep='')
  curl_download(querySchool, paste('../../schoolPolygons/', 
                                   s1_list[s, fullnames], 
                                   '.geojson', sep=''), mode = 'w')
}