title: Find whether point lies in specified polygon MongoDB
body: <p>I have following mongoDB document which represents current vehicle position by it's "GPS" field</p>
  
  <pre><code>{
          "_id" : ObjectId("565564e2f3e3f5bd2bdfad18"),
          "vehicleId" : 6521,
          "time" : 1448389800,
          "GPS" : "18.55419790592852,73.80579963326454",
          "readings" : {
                  "RPM" : {
                          "value" : 1000
                  },
                  "Speed" : {
                          "value" : 40
                  }
          }
  }
  </code></pre>
  
  <p>I need to find whether this entry falls inside the polygon specified by co-ordinates:</p>
  
  <pre><code>{lat: 18.554321, lng: 73.805231},
  {lat: 18.553838, lng: 73.804936},
  {lat: 18.553584, lng: 73.806524},
  {lat: 18.554240, lng: 73.806546},
  {lat: 18.554321, lng: 73.805231}
  </code></pre>
  
  <p>by refering GPS field present in document.</p>
  
  <p>I tried with following query but I am not getting any result: </p>
  
  <pre><code>db.data26.find(
     {
       "GPS": {
         $geoWithin: {
            $geometry: {
               type : "Polygon" ,
               coordinates: [ [ [ 73.805231, 18.554321 ], [ 73.804936, 18.553838 ], [ 73.806524, 18.553584 ], [ 73.806546, 18.554240 ], [ 73.805231, 18.554321 ] ] ]
            }
         }
       }
     }
  );
  </code></pre>
  
  <p>Any help will be appreciated</p>