在数组中查找最接近的经度和纬度? [英] Find closest longitude and latitude in array?

问题描述

我在PHP中像下面这样在字符串中具有经度和纬度

I have a longitude and latitude as a string in PHP like below

49.648881
-103.575312

我想接受它并查看一组值以找到最接近的值.数组看起来像

And I want to take that and look in an array of values to find the closest one. The array looks like

array(
'0'=>array('item1','otheritem1details....','55.645645','-42.5323'),
'1'=>array('item1','otheritem1details....','100.645645','-402.5323')
);

我想返回具有最接近的long和lad的数组.在这种情况下，它将是第一个(是的，我知道-400是不可能的值).

I want to return the array that has the closest long and lad. In this case it would be the first one (and yes I know -400 is not a a possible value).

是否有任何快速简便的方法来做到这一点?我尝试了数组搜索，但是没有用.

Is there any quick and easy way to do this? I tried array searching but that didn't work.

差异代码

function distance($lat1, $lon1, $lat2, $lon2, $unit) { 

  $theta = $lon1 - $lon2; 
  $dist = sin(deg2rad($lat1)) * sin(deg2rad($lat2)) +  cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * cos(deg2rad($theta)); 
  $dist = acos($dist); 
  $dist = rad2deg($dist); 
  $miles = $dist * 60 * 1.1515;
  $unit = strtoupper($unit);

  if ($unit == "K") {
    return ($miles * 1.609344); 
  } else if ($unit == "N") {
      return ($miles * 0.8684);
    } else {
        return $miles;
      }
}

推荐答案

您需要先将每个项目的距离映射到参考点.

You need to map the distance of each item to the reference point first.

然后您对地图进行排序，然后您可以分辨出哪个距离最小(如果反向搜索，则距离最大):

Then you sort the map and then you can tell which has the lowest (or highest if you reverse the search) distance:

$ref = array(49.648881, -103.575312);

$items = array(
    '0' => array('item1','otheritem1details....','55.645645','-42.5323'),
    '1' => array('item1','otheritem1details....','100.645645','-402.5323')
);

$distances = array_map(function($item) use($ref) {
    $a = array_slice($item, -2);
    return distance($a, $ref);
}, $items);

asort($distances);

echo 'Closest item is: ', var_dump($items[key($distances)]);

输出:

Closest item is: array(4) {
  [0]=>
  string(5) "item1"
  [1]=>
  string(21) "otheritem1details...."
  [2]=>
  string(9) "55.645645"
  [3]=>
  string(8) "-42.5323"
}

请注意，您的经度和纬度顺序正确.

Take care you have the right order of lat and long.

距离功能(仅标题略有更改，单位已删除):

The distance function (only the header slightly changed and units have been dropped):

function distance($a, $b)
{
    list($lat1, $lon1) = $a;
    list($lat2, $lon2) = $b;

    $theta = $lon1 - $lon2;
    $dist = sin(deg2rad($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;
}

这篇关于在数组中查找最接近的经度和纬度?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！