R/getGeoCode.R

In RgoogleMaps: Overlays on Static Maps

getGeoCode <- structure(function#geocoding utility
### Geocode your data using, R, JSON and Google Maps' Geocoding APIs 
### see http://allthingsr.blogspot.de/2012/01/geocode-your-data-using-r-json-and.html
### and 
(
  gcStr, ##<< adddress to geocode
  JSON = FALSE, ##<< use the JSON protocol. If FALSE, we do not have to load additional libraries
  verbose=0 ##<< level of verbosity
){
  #library("RJSONIO") #Load Library
  gcStr <- enc2utf8(gsub(' ','%20',gcStr)) #Encode URL Parameters
  if (JSON){
    #Open Connection
    # connectStr <- paste('http://maps.google.com/maps/api/geocode/json?sensor=false&address=',gcStr, sep="") 
    # if (verbose) cat("fetching ", connectStr, "\n")
    # con <- url(connectStr)
    # data.json <- fromJSON(paste(readLines(con), collapse=""))
    # close(con)
    # #Flatten the received JSON
    # data.json <- unlist(data.json)
    # lat <- data.json["results.geometry.location.lat"]
    # lng <- data.json["results.geometry.location.lng"]
    
    connectStr <- paste('http://maps.google.com/maps/api/geocode/json?sensor=false&address=',gcStr, sep="") 
    if (verbose) cat("fetching ", connectStr, "\n")
    con <- url(connectStr)
    data.json <- readLines(con)
    close(con)
    
    iLoc = grep("\"location\"", data.json,fixed=TRUE)
    iLat = grep("\"lat\"", data.json,fixed=TRUE); iLat = min(iLat[iLat>iLoc])
    lat = as.numeric(gsub(",", "",gsub("\"lat\" : ", "", data.json[iLat])))
    iLng = grep("\"lng\"", data.json,fixed=TRUE); iLng = min(iLng[iLng>iLoc])
    lng = as.numeric(gsub(",", "",gsub("\"lng\" :", "", data.json[iLng])))
    
  } else {
    #Open Connection
    connectStr <- paste('http://maps.google.com/maps/api/geocode/xml?sensor=false&address=',gcStr, sep="") 
    if (verbose) cat("fetching ", connectStr, "\n")
    con <- url(connectStr)
    data.xml <- readLines(con)
    close(con)
    #browser()
    iLoc = grep("<location>", data.xml,fixed=TRUE)
    iLat = grep("<lat>", data.xml,fixed=TRUE); iLat = min(iLat[iLat>iLoc])
    lat = as.numeric(gsub("</lat>", "",gsub("<lat>", "", data.xml[iLat])))
    iLng = grep("<lng>", data.xml,fixed=TRUE); iLng = min(iLng[iLng>iLoc])
    lng = as.numeric(gsub("</lng>", "",gsub("<lng>", "", data.xml[iLng])))
  }
  gcodes <- as.numeric(c(lat, lng))
  names(gcodes) <- c("lat", "lon")
  return (gcodes)
### returns lat/lon for address
}, ex = function(){
  getGeoCode("1600 Amphitheatre Parkway, Mountain View, CA")
  getGeoCode("Brooklyn")
  #You can run this on the entire column of a data frame or a data table:
  DF = cbind.data.frame(address=c("Berlin,Germany", "Princeton,NJ", 
            "cadillac+mountain+acadia+national+park"), lat = NA, lon = NA)
  DF <- with(DF, data.frame(address, t(sapply(DF$address, getGeoCode))))
  
})