PHP计算两个点的距离实现

两种方法，一个代码计算，一个redis计算

代码计算

```php /** * [getDistance description]根据两点的经纬度计算距离 * @param [type] $latitudeOne [description]第一个点的纬度 * @param [type] $longitudeOne [description]第一个点的经度 * @param [type] $latitudeTwo [description]第二个点的纬度 * @param [type] $longitudeTwo [description]第二个点的经度 * @return [type] [description]返回距离 */ function getDistance($latitudeOne,$longitudeOne,$latitudeTwo,$longitudeTwo){ $earthRadius = 6378137; //地球半径

    $latitudeOne = ($latitudeOne * pi()) / 180;
    $longitudeOne = ($longitudeOne * pi()) / 180;

    $latitudeTwo = ($latitudeTwo * pi()) / 180;
    $longitudeTwo = ($longitudeTwo * pi()) / 180;

    $calcLongitude = $longitudeTwo - $longitudeOne;
    $calcLatitude = $latitudeTwo - $latitudeOne;

    $stepOne = pow(sin($calcLatitude / 2),2) + cos($latitudeOne) * cos($latitudeTwo) * pow(sin($calcLongitude / 2), 2);
    $stepTwo = 2 * asin(min(1,sqrt($stepOne)));
    $calculateDistance = $earthRadius * $stepTwo;

    $kilometer = round($calculateDistance / 1000,1); //得出的$calculateDistance是米为单位，这里除1000得到km,四舍五入到小数点一位数；

    return $kilometer;

}

$res = $this->getDistance(13.361389,38.115556,13.361389,38.125566); var_dump($res); //答案是1.1

redis计算
```php
$redis = new \redis();

$redis -> connect('127.0.0.1',6379);

$redis->geoAdd("address",13.361389,38.115556,'peter',13.361389,38.125566,'peter1');//添加位置
        
$redis->geoPos("address",'peter');//位置获取
        
$res = $redis->geoDist("address",'peter','peter1','km');//两点之间的距离

var_dump($res);//答案是1.1133

//ps:redis_version > 3.2

还有个redis LBS的技巧

//接redis计算代码
$potion=['WITHDIST','count'=>2,'ASC'];//空字符串 返回key,WITHCOORD 返回key和经纬度 WITHDIST 返回key和距离 count返回几条 ASC和DESC降序和升序

$res1 = $redis->geoRadius("address",13.361389,38.115556,'2','km',$potion); //m 米 km千米

var_dump($res1);

/***
array(2) {
  [0]=>
  array(2) {
    [0]=>
    string(5) "peter"
    [1]=>
    string(6) "0.0001"
  }
  [1]=>
  array(2) {
    [0]=>
    string(6) "peter1"
    [1]=>
    string(6) "1.1134"
  }
}
***/

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