我有一个关于MySQL的几何数据类型多边形（polygon）的典型问题。
我的多边形数据以纬度和经度数组的形式存在，例如：
[["x":37.628134, "y":-77.458334],
["x":37.629867, "y":-77.449021],
["x":37.62324, "y":-77.445416],
["x":37.622424, "y":-77.457819]]
我有一个具有纬度和经度坐标的点（顶点），例如：
$location = new vertex($_GET["longitude"], $_GET["latitude"]);
现在我想找出这个顶点（点）是否在多边形内部。 我该如何在php中实现？
这是我从另一种语言转换为 PHP 的一个函数:
$vertices_x = array(37.628134, 37.629867, 37.62324, 37.622424); // x-coordinates of the vertices of the polygon
$vertices_y = array(-77.458334,-77.449021,-77.445416,-77.457819); // y-coordinates of the vertices of the polygon
$points_polygon = count($vertices_x) - 1; // number vertices - zero-based array
$longitude_x = $_GET["longitude"]; // x-coordinate of the point to test
$latitude_y = $_GET["latitude"]; // y-coordinate of the point to test
if (is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)){
echo "Is in polygon!";
}
else echo "Is not in polygon";
function is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)
{
$i = $j = $c = 0;
for ($i = 0, $j = $points_polygon ; $i < $points_polygon; $j = $i++) {
if ( (($vertices_y[$i] > $latitude_y != ($vertices_y[$j] > $latitude_y)) &&
($longitude_x < ($vertices_x[$j] - $vertices_x[$i]) * ($latitude_y - $vertices_y[$i]) / ($vertices_y[$j] - $vertices_y[$i]) + $vertices_x[$i]) ) )
$c = !$c;
}
return $c;
}
补充：
如果你需要更多的功能，我建议你使用polygon.php类，可以在这里找到。
使用你的顶点创建这个类，并将你的测试点作为输入调用isInside函数，以解决你的问题。
上面流行的答案存在拼写错误。在其他地方，这段代码已经被整理过了。更正后的代码如下：
<?php
/**
From: http://www.daniweb.com/web-development/php/threads/366489
Also see http://en.wikipedia.org/wiki/Point_in_polygon
*/
$vertices_x = array(37.628134, 37.629867, 37.62324, 37.622424); // x-coordinates of the vertices of the polygon
$vertices_y = array(-77.458334,-77.449021,-77.445416,-77.457819); // y-coordinates of the vertices of the polygon
$points_polygon = count($vertices_x); // number vertices
$longitude_x = $_GET["longitude"]; // x-coordinate of the point to test
$latitude_y = $_GET["latitude"]; // y-coordinate of the point to test
//// For testing. This point lies inside the test polygon.
// $longitude_x = 37.62850;
// $latitude_y = -77.4499;
if (is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)){
echo "Is in polygon!";
}
else echo "Is not in polygon";
function is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)
{
$i = $j = $c = 0;
for ($i = 0, $j = $points_polygon-1 ; $i < $points_polygon; $j = $i++) {
if ( (($vertices_y[$i] > $latitude_y != ($vertices_y[$j] > $latitude_y)) &&
($longitude_x < ($vertices_x[$j] - $vertices_x[$i]) * ($latitude_y - $vertices_y[$i]) / ($vertices_y[$j] - $vertices_y[$i]) + $vertices_x[$i]) ) )
$c = !$c;
}
return $c;
}
?>
With PHP
function pointInPolygon($point, $polygon, $pointOnVertex = true) {
$this->pointOnVertex = $pointOnVertex;
// Transform string coordinates into arrays with x and y values
$point = $this->pointStringToCoordinates($point);
$vertices = array();
foreach ($polygon as $vertex) {
$vertices[] = $this->pointStringToCoordinates($vertex);
}
// Check if the lat lng sits exactly on a vertex
if ($this->pointOnVertex == true and $this->pointOnVertex($point, $vertices) == true) {
return "vertex";
}
// Check if the lat lng is inside the polygon or on the boundary
$intersections = 0;
$vertices_count = count($vertices);
for ($i=1; $i < $vertices_count; $i++) {
$vertex1 = $vertices[$i-1];
$vertex2 = $vertices[$i];
if ($vertex1['y'] == $vertex2['y'] and $vertex1['y'] == $point['y'] and $point['x'] > min($vertex1['x'], $vertex2['x']) and $point['x'] < max($vertex1['x'], $vertex2['x'])) { // Check if point is on an horizontal polygon boundary
return "boundary";
}
if ($point['y'] > min($vertex1['y'], $vertex2['y']) and $point['y'] <= max($vertex1['y'], $vertex2['y']) and $point['x'] <= max($vertex1['x'], $vertex2['x']) and $vertex1['y'] != $vertex2['y']) {
$xinters = ($point['y'] - $vertex1['y']) * ($vertex2['x'] - $vertex1['x']) / ($vertex2['y'] - $vertex1['y']) + $vertex1['x'];
if ($xinters == $point['x']) { // Check if lat lng is on the polygon boundary (other than horizontal)
return "boundary";
}
if ($vertex1['x'] == $vertex2['x'] || $point['x'] <= $xinters) {
$intersections++;
}
}
}
// If the number of edges we passed through is odd, then it's in the polygon.
if ($intersections % 2 != 0) {
return "inside";
} else {
return "outside";
}
}
function pointOnVertex($point, $vertices) {
foreach($vertices as $vertex) {
if ($point == $vertex) {
return true;
}
}
}
function pointStringToCoordinates($pointString) {
$coordinates = explode(" ", $pointString);
return array("x" => $coordinates[0], "y" => $coordinates[1]);
}
// Function to check lat lng
function check(){
$points = array("22.367582 70.711816", "21.43567582 72.5811816","22.367582117085913 70.71181669186944","22.275334996986643 70.88614147123701","22.36934302329968 70.77627818998701"); // Array of latlng which you want to find
$polygon = array(
"22.367582117085913 70.71181669186944",
"22.225161442616514 70.65582486840117",
"22.20736264867434 70.83229276390898",
"22.18701840565626 70.9867880031668",
"22.22452581029355 71.0918447658621",
"22.382709129816103 70.98884793969023",
"22.40112042636022 70.94078275414336",
"22.411912121843205 70.7849142238699",
"22.367582117085913 70.71181669186944"
);
// The last lat lng must be the same as the first one's, to "close the loop"
foreach($points as $key => $point) {
echo "(Lat Lng) " . ($key+1) . " ($point): " . $this->pointInPolygon($point, $polygon) . "<br>";
}
}
With MySql
CREATE TABLE `TestPoly` (
`id` int(11) NOT NULL,
`name` varchar(255) NOT NULL,
`pol` polygon NOT NULL
)
SET @g = 'POLYGON((22.367582117085913 70.71181669186944, 22.225161442616514 70.65582486840117, 22.20736264867434 70.83229276390898, 22.18701840565626 70.9867880031668, 22.22452581029355 71.0918447658621, 22.382709129816103 70.98884793969023, 22.40112042636022 70.94078275414336, 22.411912121843205 70.7849142238699, 22.367582117085913 70.71181669186944))';
INSERT INTO TestPoly (pol) VALUES (ST_GeomFromText(@g))
set @p = GeomFromText('POINT(22.4053386588057 70.86240663480157)');
select * FROM TestPoly where ST_Contains(pol, @p);
$vertices_x = array(37.628134, 37.629867, 37.62324, 37.622424); // x-coordinates of the vertices of the polygon
$vertices_y = array(-77.458334,-77.449021,-77.445416,-77.457819); // y-coordinates of the vertices of the polygon
$points_polygon = count($vertices_x); // number vertices = number of points in a self-closing polygon
$longitude_x = $_GET["longitude"]; // x-coordinate of the point to test
$latitude_y = $_GET["latitude"]; // y-coordinate of the point to test
if (is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)){
echo "Is in polygon!";
}
else echo "Is not in polygon";
function is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)
{
$i = $j = $c = $point = 0;
for ($i = 0, $j = $points_polygon ; $i < $points_polygon; $j = $i++) {
$point = $i;
if( $point == $points_polygon )
$point = 0;
if ( (($vertices_y[$point] > $latitude_y != ($vertices_y[$j] > $latitude_y)) &&
($longitude_x < ($vertices_x[$j] - $vertices_x[$point]) * ($latitude_y - $vertices_y[$point]) / ($vertices_y[$j] - $vertices_y[$point]) + $vertices_x[$point]) ) )
$c = !$c;
}
return $c;
}
CREATE TABLE `polygons` (
`id` INT(11) NOT NULL AUTO_INCREMENT,
`polygon` POLYGON NOT NULL,
`country` VARCHAR(50) NULL DEFAULT NULL,
PRIMARY KEY (`id`),
SPATIAL INDEX `polygon` (`polygon`)
)
COLLATE='utf8mb4_0900_ai_ci'
ENGINE=InnoDB
AUTO_INCREMENT=652
;
INSERT INTO `polygons` (`country`, `polygon`) VALUES ('Thailand', ST_GEOMFROMTEXT('POLYGON((102.1728516 6.1842462,101.6894531 5.7253114,101.1401367 5.6815837,101.1181641 6.2497765,100.1074219 6.4899833,96.3281250 6.4244835,96.1083984 9.8822755,98.7670898 10.1419317,99.5800781 11.8243415,98.2177734 15.1569737,98.9868164 16.3201395,97.4267578 18.4587681,98.1079102 19.7253422,99.0087891 19.7460242,100.2612305 20.2828087,100.4809570 19.4769502,101.2060547 19.4147924,100.8544922 17.4135461,102.0849609 17.9996316,102.8320313 17.7696122,103.3593750 18.3545255,104.7875977 17.4554726,104.6337891 16.4676947,105.5126953 15.6018749,105.2270508 14.3069695,102.9858398 14.2643831,102.3486328 13.5819209,103.0297852 11.0059045,103.6669922 8.5592939,102.1728516 6.1842462))'));
我将点作为PHP函数的坐标，并使用查询比较结果与MySQL函数：
SELECT TRUE FROM `polygons` WHERE `polygons`.`country` = 'Thailand' AND ST_CONTAINS(`polygons`.`polygon`, POINT($long, $lat));
结果：
我尝试改变多边形，但php函数总是会犯错，意味着我找不到其中的错误。
找到解决方案assemblysys.com/php-point-in-polygon-algorithm - 此算法与MySQL算法相同！
比较了PHP速度和MySQL（我认为PHP应该更快），但没有。比较了47k个点。
18-06-2020 21:34:45 - PHP Speed Check Start
18-06-2020 21:34:51 - FIN! PHP Check. NOT = 41085 / IN = 5512
18-06-2020 21:34:51 - MYSQL Speed Check Start
18-06-2020 21:34:58 - FIN! MYSQL Check. NOT = 41085 / IN = 5512
更新了代码以便更容易与Google Maps一起使用： 它接受类似于以下的数组：
Array
(
[0] => stdClass Object
(
[lat] => 43.685927
[lng] => -79.745829
)
[1] => stdClass Object
(
[lat] => 43.686004
[lng] => -79.745954
)
[2] => stdClass Object
(
[lat] => 43.686429
[lng] => -79.746642
)
这样使用谷歌地图会更加容易：
function is_in_polygon2($longitude_x, $latitude_y,$polygon)
{
$i = $j = $c = 0;
$points_polygon = count($polygon)-1;
for ($i = 0, $j = $points_polygon ; $i < $points_polygon; $j = $i++) {
if ( (($polygon[$i]->lat > $latitude_y != ($polygon[$j]->lat > $latitude_y)) &&
($longitude_x < ($polygon[$j]->lng - $polygon[$i]->lng) * ($latitude_y - $polygon[$i]->lat) / ($polygon[$j]->lat - $polygon[$i]->lat) + $polygon[$i]->lng) ) )
$c = !$c;
}
return $c;
}
我在php codeigniter中编写了代码，在我的控制器中创建了两个函数，如下所示：
Original Answer翻译成"最初的回答"
public function checkLatLng(){
$vertices_y = array(22.774,22.174,22.466,22.666,22.966,22.321); // x-coordinates of the vertices of the polygon (LATITUDES)
$vertices_x = array(70.190,70.090,77.118,77.618,77.418,77.757); // y-coordinates of the vertices of the polygon (LONGITUDES)
$points_polygon = count($vertices_x)-1;
$longitude_x = $this->input->get("longitude"); // Your Longitude
$latitude_y = $this->input->get("latitude"); // Your Latitude
if ($this->is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y)){
echo "Is in polygon!";
}
else
echo "Is not in polygon";
}
最初的回答
public function is_in_polygon($points_polygon, $vertices_x, $vertices_y, $longitude_x, $latitude_y){
$i = $j = $c = $point = 0;
for ($i = 0, $j = $points_polygon ; $i < $points_polygon; $j = $i++) {
$point = $i;
if( $point == $points_polygon )
$point = 0;
if ( (($vertices_y[$point] > $latitude_y != ($vertices_y[$j] > $latitude_y)) && ($longitude_x < ($vertices_x[$j] - $vertices_x[$point]) * ($latitude_y - $vertices_y[$point]) / ($vertices_y[$j] - $vertices_y[$point]) + $vertices_x[$point]) ) )
$c = !$c;
}
return $c;
}
为了您的测试目的，我传递了以下内容：
纬度=22.808059
经度=77.522014
我的多边形：
最初的回答。