Geocoding function

This is a very simple function to perform geocoding using the Google Maps API:

getGeoCode <- function(gcStr, key)  {
  library("RJSONIO") #Load Library
  gcStr <- gsub(' ','%20',gcStr) #Encode URL Parameters
  #Open Connection
  connectStr <- paste0('https://maps.googleapis.com/maps/api/geocode/json?address=',gcStr, "&key=",key) 
  con <- url(connectStr)
  data.json <- fromJSON(paste(readLines(con), collapse=""))
  close(con)
  #Flatten the received JSON
  data.json <- unlist(data.json)
  if(data.json["status"]=="OK")   {
    lat <- data.json["results.geometry.location.lat"]
    lng <- data.json["results.geometry.location.lng"]
    gcodes <- c(lat, lng)
    names(gcodes) <- c("Lat", "Lng")
    return (gcodes)
  }
}

Essentially, users need to get an API key from google and then use as an input (string) for the function. The function itself is very simple, and it is an adaptation of some code I found on-line (unfortunately I did not write down where I found the original version so I do not have a way to reference the source, sorry!!).

geoCodes <- getGeoCode(gcStr="11 via del piano, empoli", key)

To use the function we simply need to include an address, and it will return its coordinates in WGS84.
It can be used in a mutate call within dplyr and it is reasonably fast.

The repository is here:
https://github.com/fveronesi/RGeocode.r

Live Earthquake Map with Shiny and Google Map API

In the post Exchange data between R and the Google Maps API using Shiny I presented a very simple way to allow communication between R and javascript using Shiny.

This is an example of a practical approach for which the same system can be used. Here I created a tool to visualize seismic events, collected from USGS, in the Google Maps API using R to do some basic data preparation. The procedure to complete this experiment is pretty much identical to what I presented in the post mentioned above, so I will not repeated here.


The final map looks like this:

and it is accessible from this site, hosted on the Amazon Cloud: Earthquake

The colours of the markers depends on magnitude and they are set in R. For magnitudes below 2 the marker is green, between 2 and 4 is yellow, between 4 and 6 is orange and above 6 is red.
I also set R to export other information about the event to the json file that I then use to populate the infowindow of each marker.

The code for creating this map consists of two pieces, an index.html file (which needs to go in a folder names www) and the file server.r, available below:

Server.r

 # server.R  
 #Title: Earthquake Visualization in Shiny  
 #Copyright: Fabio Veronesi  
   
 library(sp)  
 library(rjson)  
 library(RJSONIO)  
   
    
 shinyServer(function(input, output) {  
   
 output$json <- reactive ({  
 if(length(input$Earth)>0){  
 if(input$Earth==1){  
 hour <- read.table("http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_hour.csv", sep = ",", header = T)  
 if(nrow(hour)>0){  
 lis <- list()  
 for(i in 1:nrow(hour)){  
   
 if(hour$mag[i]<=2){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_green.png"}  
 else if(hour$mag[i]>2&hour$mag[i]<=4){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_yellow.png"}  
 else if(hour$mag[i]>4&hour$mag[i]<=6){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_orange.png"}  
 else {icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_red.png"}  
   
 Date.hour <- substring(hour$time[i],1,10)  
 Time.hour <- substring(hour$time[i],12,23)  
   
 lis[[i]] <- list(i,hour$longitude[i],hour$latitude[i],icon,hour$place[i],hour$depth[i],hour$mag[i],Date.hour,Time.hour)  
 }  
   
   
 #This code creates the variable test directly in javascript for export the grid in the Google Maps API  
 #I have taken this part from:http://stackoverflow.com/questions/26719334/passing-json-data-to-a-javascript-object-with-shiny  
    paste('<script>test=',         
       RJSONIO::toJSON(lis),        
       ';setAllMap();Cities_Markers();',        
       '</script>')  
 }  
 }  
   
 else if(input$Earth==4){  
 month <- read.table("http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_month.csv", sep = ",", header = T)  
 if(nrow(month)>0){  
 lis <- list()  
 for(i in 1:nrow(month)){  
   
 if(month$mag[i]<=2){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_green.png"}  
 else if(month$mag[i]>2&month$mag[i]<=4){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_yellow.png"}  
 else if(month$mag[i]>4&month$mag[i]<=6){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_orange.png"}  
 else {icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_red.png"}  
   
 Date.month <- substring(month$time[i],1,10)  
 Time.month <- substring(month$time[i],12,23)  
   
 lis[[i]] <- list(i,month$longitude[i],month$latitude[i],icon,month$place[i],month$depth[i],month$mag[i],Date.month,Time.month)  
 }  
   
   
 #This code creates the variable test directly in javascript for export the grid in the Google Maps API  
 #I have taken this part from:http://stackoverflow.com/questions/26719334/passing-json-data-to-a-javascript-object-with-shiny  
    paste('<script>test=',         
       RJSONIO::toJSON(lis),        
       ';setAllMap();Cities_Markers();',        
       '</script>')  
 }  
 }  
   
   
 else if(input$Earth==3){  
 week <- read.table("http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_week.csv", sep = ",", header = T)  
 if(nrow(week)>0){  
 lis <- list()  
 for(i in 1:nrow(week)){  
   
 if(week$mag[i]<=2){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_green.png"}  
 else if(week$mag[i]>2&week$mag[i]<=4){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_yellow.png"}  
 else if(week$mag[i]>4&week$mag[i]<=6){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_orange.png"}  
 else {icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_red.png"}  
   
 Date.week <- substring(week$time[i],1,10)  
 Time.week <- substring(week$time[i],12,23)  
   
 lis[[i]] <- list(i,week$longitude[i],week$latitude[i],icon,week$place[i],week$depth[i],week$mag[i],Date.week,Time.week)  
 }  
   
   
 #This code creates the variable test directly in javascript for export the grid in the Google Maps API  
 #I have taken this part from:http://stackoverflow.com/questions/26719334/passing-json-data-to-a-javascript-object-with-shiny  
    paste('<script>test=',         
       RJSONIO::toJSON(lis),        
       ';setAllMap();Cities_Markers();',        
       '</script>')  
 }  
 }  
   
   
   
   
 else {  
 day <- read.table("http://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_day.csv", sep = ",", header = T)  
 if(nrow(day)>0){  
 lis <- list()  
 for(i in 1:nrow(day)){  
   
 if(day$mag[i]<=2){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_green.png"}  
 else if(day$mag[i]>2&day$mag[i]<=4){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_yellow.png"}  
 else if(day$mag[i]>4&day$mag[i]<=6){icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_orange.png"}  
 else {icon="http://maps.gstatic.com/mapfiles/ridefinder-images/mm_20_red.png"}  
   
 Date.day <- substring(day$time[i],1,10)  
 Time.day <- substring(day$time[i],12,23)  
   
 lis[[i]] <- list(i,day$longitude[i],day$latitude[i],icon,day$place[i],day$depth[i],day$mag[i],Date.day,Time.day)  
 }  
   
   
 #This code creates the variable test directly in javascript for export the grid in the Google Maps API  
 #I have taken this part from:http://stackoverflow.com/questions/26719334/passing-json-data-to-a-javascript-object-with-shiny  
    paste('<script>test=',         
       RJSONIO::toJSON(lis),        
       ';setAllMap();Cities_Markers();',        
       '</script>')  
 }  
 }  
 }  
 })  
 })  
   

Index.html

 <!DOCTYPE html>  
 <html>  
 <head>  
 <title>Earthquake Visualization in Shiny</title>  
   
 <!--METADATA-->    
 <meta name="author" content="Fabio Veronesi">  
 <meta name="copyright" content="©Fabio Veronesi">  
 <meta http-equiv="Content-Language" content="en-gb">  
 <meta charset="utf-8"/>  
   
 <style type="text/css">  
   
 html { height: 100% }  
 body { height: 100%; margin: 0; padding: 0 }  
 map-canvas { height: 100%; width:100% }  
   
 .btn {  
  background: #dde6d8;  
  background-image: -webkit-linear-gradient(top, #dde6d8, #859ead);  
  background-image: -moz-linear-gradient(top, #dde6d8, #859ead);  
  background-image: -ms-linear-gradient(top, #dde6d8, #859ead);  
  background-image: -o-linear-gradient(top, #dde6d8, #859ead);  
  background-image: linear-gradient(to bottom, #dde6d8, #859ead);  
  -webkit-border-radius: 7;  
  -moz-border-radius: 7;  
  border-radius: 7px;  
  font-family: Arial;  
  color: #000000;  
  font-size: 20px;  
  padding: 9px 20px 10px 20px;  
  text-decoration: none;  
 }  
   
 .btn:hover {  
  background: #f29f9f;  
  background-image: -webkit-linear-gradient(top, #f29f9f, #ab1111);  
  background-image: -moz-linear-gradient(top, #f29f9f, #ab1111);  
  background-image: -ms-linear-gradient(top, #f29f9f, #ab1111);  
  background-image: -o-linear-gradient(top, #f29f9f, #ab1111);  
  background-image: linear-gradient(to bottom, #f29f9f, #ab1111);  
  text-decoration: none;  
 }  
   
 </style>  
   
        
 <script type="text/javascript" src="http://google-maps-utility-library-v3.googlecode.com/svn/tags/markerclusterer/1.0/src/markerclusterer.js"></script>  
   
 <script src="https://maps.googleapis.com/maps/api/js?v=3.exp&signed_in=true&libraries=drawing"></script>  
   
 <script type="application/shiny-singletons"></script>  
 <script type="application/html-dependencies">json2[2014.02.04];jquery[1.11.0];shiny[0.11.1];ionrangeslider[2.0.2];bootstrap[3.3.1]</script>  
 <script src="shared/json2-min.js"></script>  
 <script src="shared/jquery.min.js"></script>  
 <link href="shared/shiny.css" rel="stylesheet" />  
 <script src="shared/shiny.min.js"></script>  
 <link href="shared/ionrangeslider/css/normalize.css" rel="stylesheet" />  
 <link href="shared/ionrangeslider/css/ion.rangeSlider.css" rel="stylesheet" />  
 <link href="shared/ionrangeslider/css/ion.rangeSlider.skinShiny.css" rel="stylesheet" />  
 <script src="shared/ionrangeslider/js/ion.rangeSlider.min.js"></script>  
 <link href="shared/bootstrap/css/bootstrap.min.css" rel="stylesheet" />  
 <script src="shared/bootstrap/js/bootstrap.min.js"></script>  
 <script src="shared/bootstrap/shim/html5shiv.min.js"></script>  
 <script src="shared/bootstrap/shim/respond.min.js"></script>  
   
        
      <script type="text/javascript">  
      var map = null;  
      var Gmarkers = [];  
        
   
      function Cities_Markers() {  
             
           var infowindow = new google.maps.InfoWindow({ maxWidth: 500,maxHeight:500 });  
   
           //Loop to add markers to the map based on the JSON exported from R, which is within the variable test  
           for (var i = 0; i < test.length; i++) {   
                var lat = test[i][2]  
                var lng = test[i][1]  
                var marker = new google.maps.Marker({  
                     position: new google.maps.LatLng(lat, lng),  
                     title: 'test',  
                     map: map,  
                     icon:test[i][3]  
                });  
             
           //This sets up the infowindow  
           google.maps.event.addListener(marker, 'click', (function(marker, i) {  
                return function() {  
                     infowindow.setContent('<div id="content"><p><b>Location</b> = '+  
                     test[i][4]+'<p>'+  
                     '<b>Depth</b> = '+test[i][5]+'Km <p>'+  
                     '<b>Magnitude</b> = '+test[i][6]+ '<p>'+  
                     '<b>Date</b> = '+test[i][7]+'<p>'+  
                     '<b>Time</b> = '+test[i][8]+'</div>');  
                     infowindow.open(map, marker);  
                }  
                })(marker, i));  
           Gmarkers.push(marker);  
           };  
             
   
      };  
   
      //Function to remove all the markers from the map  
      function setAllMap() {  
           for (var i = 0; i < Gmarkers.length; i++) {  
                Gmarkers[i].setMap(null);  
           }  
 }  
        
      //Initialize the map  
      function initialize() {  
           var mapOptions = {  
           center: new google.maps.LatLng(31.6, 0),  
           zoom: 3,  
           mapTypeId: google.maps.MapTypeId.TERRAIN  
      };  
   
      map = new google.maps.Map(document.getElementById('map-canvas'),mapOptions);  
        
    
 }  
   
   
 google.maps.event.addDomListener(window, 'load', initialize);  
   </script>  
        
   
 </head>  
   
   
 <body>  
   
  <div id="json" class="shiny-html-output"></div>  
   
    
  <button type="button" class="btn" id="hour" onClick="Shiny.onInputChange('Earth', 1)" style="position:absolute;top:1%;left:1%;width:100px;z-index:999">Last Hour</button>  
  <button type="button" class="btn" id="day" onClick="Shiny.onInputChange('Earth', 2)" style="position:absolute;top:1%;left:10%;width:100px;z-index:999">Last Day</button>  
  <button type="button" class="btn" id="week" onClick="Shiny.onInputChange('Earth', 3)" style="position:absolute;top:1%;left:20%;width:100px;z-index:999">Last Week</button>  
  <button type="button" class="btn" id="month" onClick="Shiny.onInputChange('Earth', 4)" style="position:absolute;top:1%;left:30%;width:100px;z-index:999">Last Month</button>  
    
  <div id="map-canvas" style="top:0%;right:0%;width:100%;height:100%;z-index:1"></div>  
    
    
    
 </body>  
 </html>  

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