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root / class / GeoPoint.class.php @ 8e9363c4

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<?php
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require_once(dirname(__FILE__).'/utils.class.php');
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interface LatLon {
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  public function get_lat();
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  public function get_lon();
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}
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interface Collection {
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  public static function get_all();
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}
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abstract class GeoPoint implements LatLon, Collection {
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  /**  distance, by Vincenty formula
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       see http://stackoverflow.com/a/10054282
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   */
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  public function distance($other_point) {
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    $earthRadius = 6371;
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        // convert from degrees to radians
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        $latFrom = deg2rad($this->get_lat());
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        $lonFrom = deg2rad($this->get_lon());
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        $latTo = deg2rad($other_point->get_lat());
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        $lonTo = deg2rad($other_point->get_lon());
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        $lonDelta = $lonTo - $lonFrom;
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        $a = pow(cos($latTo) * sin($lonDelta), 2) +
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          pow(cos($latFrom) * sin($latTo) -
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      sin($latFrom) * cos($latTo) * cos($lonDelta), 2);
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        $b = sin($latFrom) * sin($latTo) +
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      cos($latFrom) * cos($latTo) * cos($lonDelta);
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        $angle = atan2(sqrt($a), $b);
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        return $angle * $earthRadius;
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  }
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  /** Gets only the points in a circle of $distance km arround $opint
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     @param $target a LatLon
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   */
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  public static function near_points($target, $distance) {
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    $near_points = array();
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    foreach (static::get_all() as $point) {
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      if ($point->distance($target) < $distance) {
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        $near_points[] = $point;
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      }
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    }
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    return $near_points;
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  }
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}
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?>