排序数组，从数组计算

Question

我从数据库中的用户的纬度和经度阵列中的 ，我有我的纬度和经度

现在我想计算距离和排序从我的数据库用户与

$mylat = $_SESSION['lat']; 
$mylng = $_SESSION['lng']; 

$statement = $pdo->prepare("SELECT * FROM users"); 
$statement->execute(); 
$users = $statement->fetchAll(); 

foreach($users as $row){ 
    $dist = 0.0; 
    $x1 = $mylng; 
    $x2 = $row['lng']; 
    $y1 = $mylat; 
    $y2 = $row['lat']; 

    $dist = acos(sin($x1=deg2rad($x1))*sin($x2=deg2rad($x2))+cos($x1)*cos($x2)*cos(deg2rad($y2) - deg2rad($y1)))*(6378.137); 
    $distn = FLOOR (ROUND($dist,1) * 2)/2 ; 
} 

sort($distn); 

foreach ($users as $row) { 

$dist = 0.0; 
    $x1 = $mylng; 
    $x2 = $row['lng']; 
    $y1 = $mylat; 
    $y2 = $row['lat']; 

    $dist = acos(sin($x1=deg2rad($x1))*sin($x2=deg2rad($x2))+cos($x1)*cos($x2)*cos(deg2rad($y2) - deg2rad($y1)))*(6378.137); 
    $distn = FLOOR (ROUND($dist,1) * 2)/2 ; 

echo $row['username']; 
echo $distn; 

} 

所以在第一的foreach我计算我的每个用户的距离。 比我想排序的距离后，我的用户，并显示他们 与那里的名字和有我的距离。

user1 0.5km distance 
user2 1km distance 

但我不会工作。 感谢您的帮助:)

Answer 1

创建一个距离函数：

function getDistance ($lat, $lon) 
{ 
    global $mylng, $mylat; 
    $x1 = deg2rad($mylng); 
    $x2 = deg2rad($lon); 
    $y1 = deg2rad($mylat); 
    $y2 = deg2rad($lat); 

    $dist = acos(sin($x1)*sin($x2)+cos($x1)*cos($x2)*cos($y2 - $y1))*(6378.137); 
    return $dist; 
} 

创建一个比较函数：

function compareDistance ($user1, $user2) 
{ 
    return getDistance ($user1['lat'], $user1['lng']) - getDistance ($user2['lat'], $user2['lng']); 
} 

然后你就可以通过uasort通过您的数组：

uasort ($users, 'compareDistance'); 

有关更多信息，请参阅http://php.net/manual/en/function.uasort.php。

编辑：

您的程序可以被改写：

function getDistance ($lat, $lon) 
{ 
    global $mylng, $mylat; 

    $x1 = deg2rad($mylng); 
    $x2 = deg2rad($lon); 
    $y1 = deg2rad($mylat); 
    $y2 = deg2rad($lat); 

    $dist = acos(sin($x1)*sin($x2)+cos($x1)*cos($x2)*cos($y2 - $y1))*(6378.137); 
    return $dist; 
} 

function compareDistance ($user1, $user2) 
{ 
    return getDistance ($user1['lat'], $user1['lng']) - getDistance ($user2['lat'], $user2['lng']); 
} 

$mylat = $_SESSION['lat']; 
$mylng = $_SESSION['lng']; 

$statement = $pdo->prepare("SELECT * FROM users"); 
$statement->execute(); 
$users = $statement->fetchAll(); 

uasort ($users, 'compareDistance'); 

foreach ($users as $row) { 
    $dist = getDistance ($row['lat'], $row['lng']); 
    $distn = floor(round($dist,1) * 2)/2 ; 

    echo $row['username']. ": " . $distn . "km distance"; 
}