Saturday, March 17, 2012

Geocode and reverse geocode your data using, R, JSON and Google Maps' Geocoding API

(Reposting the previous blog with additional module on reverse geocoding added here.)

First and foremost, I absolutely love the topic of Location Analytics (Geo-Spatial Analysis) and see tremendous business potential in not so distant future.  I would go out on a limb to predict that the Location Analytics will soon go viral in the enterprise space because it has the capability to WOW us. Look no further than your iPhone or an Android phone and count how many location aware apps you have. We all have at lease one app - Google Maps.  Mobile is one of the strongest catalyst for enterprise adoption of Location aware apps. All right, enough of business talk, let's get dirty with the code.

Over the last year and half, I have faced numerous challenges with geocoding and reverse geocoding the data that I have used to showcase my passion for location analytics.  In 2012, I decided to take thing in my control and turned to R.  Here, I am sharing a simple R script that I wrote to geo-code my data whenever I needed it, even BIG Data.

To geocode and reverse geocode my data, I use Google's Geocoding service which returns the geocoded data in a JSON. I will recommend that you register with Google Maps API and get a key if you have large amount of data and would do repeated geo coding.


getGeoCode <- function(gcStr)  {
  library("RJSONIO") #Load Library
  gcStr <- gsub(' ','%20',gcStr) #Encode URL Parameters
 #Open Connection
 connectStr <- paste('',gcStr, sep="") 
  con <- url(connectStr)
  data.json <- fromJSON(paste(readLines(con), collapse=""))
  #Flatten the received JSON
  data.json <- unlist(data.json)
  if(data.json["status"]=="OK")   {
    lat <- data.json[""]
    lng <- data.json["results.geometry.location.lng"]
    gcodes <- c(lat, lng)
    names(gcodes) <- c("Lat", "Lng")
    return (gcodes)
geoCodes <- getGeoCode("Palo Alto,California")

> geoCodes
           Lat            Lng 
  "37.4418834" "-122.1430195" 

Reverse Geocode:
reverseGeoCode <- function(latlng) {
latlngStr <-  gsub(' ','%20', paste(latlng, collapse=","))#Collapse and Encode URL Parameters
  library("RJSONIO") #Load Library
  #Open Connection
  connectStr <- paste('',latlngStrsep="")
  con <- url(connectStr)
  data.json <- fromJSON(paste(readLines(con), collapse=""))
  #Flatten the received JSON
  data.json <- unlist(data.json)
    address <- data.json["results.formatted_address"]
  return (address)
address <- reverseGeoCode(c(37.4418834, -122.1430195))

> address
"668 Coleridge Ave, Palo Alto, CA 94301, USA" 

Happy Coding!

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