检查坐标是否在与其他坐标的特定距离内 [英] Check if coordinates is within a specific distance from other coordinates
问题描述
好,所以我在某些坐标上有一个目标,而在其他坐标上有一些人",并且我想检查这些人的坐标是否在距目标坐标2公里(2000m)的距离之内.
Ok, so I have a target on certain coordinates, and some 'persons' on other coordinates, and I want to check if the persons coordinates is within a 2km (2000m) distance from the target coordinates.
下面的代码只是为了说明我想要更清楚地说明,当然问题是如何做到这一点?非常感谢您提供解决方案,谢谢!
The code below is just to illustrate what I want more clear, and the question is of course how could this be done? I would really appreciate a solution to this one, thanks!
$person0 = Array('56.34342', '49.324523');
$person1 = Array('57.49544', '47.421524');
$person2 = Array('56.74612', '48.722323');
$target = Array('56.35343', '49.342343');
for (var $i = 0; $i < 4; i$++) {
CheckIfMatch($person + i$);
}
function CheckIfMatch($person) {
if($person is within 2km from target) {
echo 'Match!';
}
}
推荐答案
您可以使用Great Circle算法来做到这一点. http://en.wikipedia.org/wiki/Great-circle_distance
You can do this using Great Circle algorithms. http://en.wikipedia.org/wiki/Great-circle_distance
这是找到距离的方法.
编辑
这是您执行此操作的完整代码!
Here is the full code for you to do that!
<?php
$persons = Array();
$persons[] = Array('52.00951','4.36052');//Delft is more than 2 km from den haag
$persons[] = Array('52.03194','4.31769');//Rijswijk is less than 2 km from den haag
$persons[] = Array('52.07097','4.29945');//A place near den Haag almost 2 streets from center and my favourite coffee shop
$persons[] = Array('52.37022','4.89517');//Amsterdamn is about 60 km *DRIVING* from the hagues according to Gmaps
$target = Array('52.07050', '4.30070');//Den Haag
$i = 0;
foreach($persons as $person){
$i++;
$distance = calculate_distance($person, $target);
if($distance <= 2 ){
echo "Person $i is within 2km with a distance to taget of $distance</br>";
}else{
echo "Person $i is <b>not</b> within 2km with a distance to taget of $distance</br>";
}
}
function calculate_distance($person, $target){
$lat1 = $person[0];
$lng1 = $person[1];
$lat2 = $target[0];
$lng2 = $target[1];
$pi = 3.14159;
$rad = doubleval($pi/180.0);
$lon1 = doubleval($lng1)*$rad;
$lat1 = doubleval($lat1)*$rad;
$lon2 = doubleval($lng2)*$rad;
$lat2 = doubleval($lat2)*$rad;
$theta = $lng2 - $lng1;
$dist = acos(sin($lat1) * sin($lat2) + cos($lat1) * cos($lat2) * cos($theta));
if ($dist < 0)
$dist += $pi;
$miles = doubleval($dist * 69.1);
$inches = doubleval($miles * 63360);
$km = doubleval($dist * 115.1666667);
$dist = sprintf( "%.2f",$dist);
$miles = sprintf( "%.2f",$miles);
$inches = sprintf( "%.2f",$inches);
$km = sprintf( "%.2f",$km);
//Here you can return whatever you please
return $km;
}
?>
当然还有结果:
Person 1 is not within 2km with a distance to taget of 4.24
Person 2 is within 2km with a distance to taget of 1.21
Person 3 is within 2km with a distance to taget of 0.09
Person 4 is not within 2km with a distance to taget of 41.56
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