Now that we know the latitude and longitude of the user’s current location and the range we are going to search, i.e. a center point and radius, the maximum and minimum values of longitude and latitude.
First declare a function to calculate the range of latitude and longitude
/**
* Calculate the range based on the latitude, longitude and radius
* @param string $latitude
* @param String $longitude
* @param float $radius
* @return Array
*/
private function calcScope($latitude, $longitude, $radius) {
$degree = (24901 * 1609) / 360.0;
$dpmLatitude = 1 / $degree;
$radiusLatitude = $dpmLatitude * $radius;
$minLatitude = $latitude - $radiusLatitude; // min latitude
$maxLatitude = $latitude + $radiusLatitude; // max latitude
$mpdLongitude = $degree * cos($latitude * (PI / 180));
$dpmLongitude = 1 / $mpdLongitude;
$radiusLongitude = $dpmLongitude * $radius;
$minLongitude = $longitude - $radiusLongitude; // min longitude
$maxLongitude = $longitude + $radiusLongitude; // max longitude
$scope = array(
'minLatitude' => $minLatitude,
'maxLatitude' => $maxLatitude,
'minLongitude' => $minLongitude,
'maxLongitude' => $maxLongitude
);
return $scope;
} The returned array contains the maximum and minimum latitude and longitude that meet the conditions
Then we can find all the records that meet the conditions from the database
/**
* search those latitude, longitude are within range
* @param String $latitude
* @param String $longitude
* @param float $radius
* @return Array
*/
public function searchByLatAndLng($latitude, $longitude, $radius) {
$scope = $this->calcScope($latitude, $longitude, $radius); // get the min and max for latitude and logitude
$sql = 'SELECT id, type, latitude, longitude FROM last_location WHERE `latitude` < '.$scope['maxLatitude'].' and `latitude` > '.$scope['minLatitude'].' and `longitude` < '.$scope['maxLongitude'].' and `longitude` > '.$scope['minLongitude'];
$sth = $dbh->query($sql);
$result = $sth->fetchAll(PDO::FETCH_ASSOC);
return $result;
} Now we have the result that are within the range, we could calculate the actual distance.
/**
* calculate the distance (KM)
* @param string $lat1 latitude 1
* @param String $lng1 longitude 1
* @param String $lat2 latitude 2
* @param String $lng2 longitude 2
* @return float return the distance in km
*/
public function calcDistance($lat1, $lng1, $lat2, $lng2) {
$lat1 = doubleval($lat1);
$lng1 = doubleval($lng1);
$lat2 = doubleval($lat2);
$lng2 = doubleval($lng2);
/** calculation by google */
$theta = $lng1 - $lng2;
$dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta));
$dist = acos($dist);
$dist = rad2deg($dist);
$miles = $dist * 60 * 1.1515;
return ($miles * 1.609344);
}