added method to aggrerate by key

lib/torque/provider.jsonarray.js

@@ -22,6 +22,35 @@
 
   json.prototype = {
 
+    //
+    // return the data aggregated by key:
+    // {
+    //  key0: 12,
+    //  key1: 32
+    //  key2: 25
+    // }
+    //
+    aggregateByKey: function(rows) {
+      function getKeys(row) {
+        var HEADER_SIZE = 3;
+        var valuesCount = row.data[2];
+        var keys = {};
+        for (var s = 0; s < valuesCount; ++s) {
+          keys[row.data[HEADER_SIZE + s]] = row.data[HEADER_SIZE + valuesCount + s];
+        }
+        return keys;
+      }
+      var keys = {};
+      for (r = 0; r < rows.length; ++r) {
+        var rowKeys = getKeys(rows[r]);
+        for(var k in rowKeys) {
+          keys[k] = keys[k] || 0;
+          keys[k] += rowKeys[k];
+        }
+      }
+      return keys;
+    },
+
     /**
      *
      */
@@ -131,6 +160,26 @@
       return this.options.url;
     },
 
+
+    getTile: function(coord, zoom, callback) {
+      var template = this.url();
+      template = template
+        .replace('{x}', coord.x)
+        .replace('{y}', coord.y)
+        .replace('{z}', zoom);
+
+      var self = this;
+      var fetchTime = Profiler.metric('jsonarray:fetch time');
+      fetchTime.start();
+      torque.net.get(template, function (data) {
+        fetchTime.end();
+        if(data) {
+          data = JSON.parse(data.responseText);
+        }
+        callback(data);
+      });
+    },
+
     /**
      * `coord` object like {x : tilex, y: tiley } 
      * `zoom` quadtree zoom level