calculate the trip distance and duration from the actual location data

compass/app/Jobs/TripComplete.php

@@ -176,6 +176,31 @@ class TripComplete extends Job implements SelfHandling, ShouldQueue
       ];
     }
 
+    // If there is trip data, recalculate the distance and duration based on the actual data
+    if(count($features)) {
+      $startTime = strtotime($features[0]->properties['timestamp']);
+      $endTime = strtotime($features[count($features)-1]->properties['timestamp']);
+      $duration = $endTime - $startTime;
+      $params['trip']['properties']['duration']['properties']['num'] = $duration;
+      Log::debug("Overriding duration to $duration");
+
+      $points = array_map(function($f){
+        return $f->geometry->coordinates;
+      }, $features);
+      $simple = $this->_ramerDouglasPeucker($points, 0.0001);
+      $last = false;
+      $distance = 0;
+      foreach($simple as $p) {
+        if($last) {
+          $distance += $this->_gc_distance($p[1], $p[0], $last[1], $last[0]);
+        }
+        $last = $p;
+      }
+      if($distance) {
+        $params['trip']['properties']['distance']['properties']['num'] = $distance;
+        Log::debug("Overriding distance to $distance");
+      }
+    }
 
     // echo "Micropub Params\n";
     // print_r($params);
@@ -218,4 +243,102 @@ class TripComplete extends Job implements SelfHandling, ShouldQueue
     }
   }
 
+
+
+
+
+
+  // TODO: move this to a library p3k/Geo
+
+
+  // http://www.loughrigg.org/rdp/
+
+  //The author has placed this work in the Public Domain, thereby relinquishing all copyrights.
+  //You may use, modify, republish, sell or give away this work without prior consent.
+  //This implementation comes with no warranty or guarantee of fitness for any purpose.
+
+  //=========================================================================
+  //An implementation of the Ramer-Douglas-Peucker algorithm for reducing
+  //the number of points on a polyline
+  //see http://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm
+  //=========================================================================
+
+  //Finds the perpendicular distance from a point to a straight line.
+  //The coordinates of the point are specified as $ptX and $ptY.
+  //The line passes through points l1 and l2, specified respectively with their
+  //coordinates $l1x and $l1y, and $l2x and $l2y
+  public function _perpendicularDistance($ptX, $ptY, $l1x, $l1y, $l2x, $l2y)
+  {
+      $result = 0;
+      if ($l2x == $l1x)
+      {
+          //vertical lines - treat this case specially to avoid divide by zero
+          $result = abs($ptX - $l2x);
+      }
+      else
+      {
+          $slope = (($l2y-$l1y) / ($l2x-$l1x));
+          $passThroughY = (0-$l1x)*$slope + $l1y;
+          $result = (abs(($slope * $ptX) - $ptY + $passThroughY)) / (sqrt($slope*$slope + 1));
+      }
+      return $result;
+  }
+
+  //RamerDouglasPeucker
+  //Reduces the number of points on a polyline by removing those that are closer to the line
+  //than the distance $epsilon.
+  //The polyline is provided as an array of arrays, where each internal array is one point on the polyline,
+  //specified by easting (x-coordinate) with key "0" and northing (y-coordinate) with key "1".
+  //It is assumed that the coordinates and distance $epsilon are given in the same units.
+  //The result is returned as an array in a similar format.
+  //Each point returned in the result array will retain all its original data, including its E and N
+  //values along with any others.
+  public function _ramerDouglasPeucker($pointList, $epsilon)
+  {
+      if(count($pointList) == 0)
+        return array();
+
+      // Find the point with the maximum distance
+      $dmax = 0;
+      $index = 0;
+      $totalPoints = count($pointList);
+      for ($i = 1; $i < ($totalPoints - 1); $i++)
+      {
+          $d = $this->_perpendicularDistance($pointList[$i][0], $pointList[$i][1],
+                                     $pointList[0][0], $pointList[0][1],
+                                     $pointList[$totalPoints-1][0], $pointList[$totalPoints-1][1]);
+
+          if ($d > $dmax)
+          {
+              $index = $i;
+              $dmax = $d;
+          }
+      }
+
+      $resultList = array();
+
+      // If max distance is greater than epsilon, recursively simplify
+      if ($dmax >= $epsilon)
+      {
+          // Recursive call
+          $recResults1 = $this->_ramerDouglasPeucker(array_slice($pointList, 0, $index + 1), $epsilon);
+          $recResults2 = $this->_ramerDouglasPeucker(array_slice($pointList, $index, $totalPoints - $index), $epsilon);
+
+          // Build the result list
+          $resultList = array_merge(array_slice($recResults1, 0, count($recResults1) - 1),
+                                    array_slice($recResults2, 0, count($recResults2)));
+      }
+      else
+      {
+          $resultList = array($pointList[0], $pointList[$totalPoints-1]);
+      }
+      // Return the result
+      return $resultList;
+  }
+
+  function _gc_distance($lat1, $lng1, $lat2, $lng2) {
+    return ( 6378100 * acos( cos( deg2rad($lat1) ) * cos( deg2rad($lat2) ) * cos( deg2rad($lng2) - deg2rad($lng1) ) + sin( deg2rad($lat1) ) * sin( deg2rad($lat2) ) ) );
+  }
+
+
 }