javascript - How to get the user's latitude and longitude and calculate the distance between two locations?-PHP Tutorial-php.cn

javascript - How to get the user's latitude and longitude and calculate the distance between two locations?

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Release： 2016-09-19 09:16:32

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How to get the latitude and longitude of my current location? After knowing the longitude and latitude of two places, how to calculate the distance between the two places?
I am currently working on a public account. I need to obtain the user’s latitude and longitude, and then calculate the distance between the user’s longitude and latitude and another location? How can I achieve this? Please help me, thank you!

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PHP implements the "nearby people" function, determines longitude and latitude based on IP, and calculates distance based on longitude and latitude

PHP installs the GeoIP extension and database to obtain the visitor's country/city/latitude and longitude based on the IP. Then you can use
geoip_record_by_name($_SERVER['REMOTE_ADDR'])to determine the latitude and longitude based on the user's IP.Note: geoip_record_by_name() returns The west longitude and south latitude are negative numbers.

5000 meters converted into latitude and longitude:

Latitude: 1 deg = 110852 m
Longitude: 1 deg = 111320*cos(lat) m
On the same longitude line, the difference of one latitude is about 110852 meters
On the same latitude line, the difference of one longitude About 111320*cos(lat) meters (lat is the latitude of the latitude)

<code><?php
//以当前用户经纬度为中心,查询5000米内的其他用户
$y = 5000 / 110852; //纬度的范围
$x = 5000 / (111320*cos($lat)); //经度的范围
$sql = '
    select * from user where 
    lat >= ($lat-$y) and lat <= ($lat+$y) and 
    lon >= ($lon-$x) and lon <= ($lon+$x);
';</code>

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There are two fields in the database user table, which store the user's longitude lat and latitude lon respectively.

($lat-$y) <= lat <= ($lat+$y)
($lon-$x) < ;= lon <= ($lon+$x)
This range is a rough range, just calculate the distance below and remove users who are more than 5 kilometers away.

According to the user’s longitude and latitude queried above,

Use the Haversine formula to calculate the distance between two points based on the latitude and longitude:

<code><?php
function distance($lat1, $lon1, $lat2, $lon2) {
    $R = 6371393; //地球平均半径,单位米
    $dlat = deg2rad($lat2-$lat1);
    $dlon = deg2rad($lon2-$lon1);
    $a = pow(sin($dlat/2), 2) + cos(deg2rad($lat1)) * cos(deg2rad($lat2)) * pow(sin($dlon/2), 2);
    $c = 2 * atan2(sqrt($a), sqrt(1-$a));
    $d = $R * $c;
    return round($d);
}
echo distance(0, 0, -1, 0); // 111202米</code>

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Then you can use uasort or array_multisort to list the users from nearest to far. For example, there are three users named win, osx, and lin:

<code><?php
$arr = array(
    'win' => array(
        'dis' => 1024,
        'age' => 31
    ),
    'osx' => array(
        'dis' => 512,
        'age' => 15
    ),
    'lin' => array(
        'dis' => 512,
        'age' => 25
    )
);
foreach($arr as $k => $v) {
    $sort['dis'][$k] = $v['dis'];
    $sort['age'][$k] = $v['age'];
}
//先按距离升序排序,如果距离相同,则按年龄降序排序
array_multisort($sort['dis'], SORT_ASC, $sort['age'], SORT_DESC, $arr);
echo json_encode($arr);
//{"lin":{"dis":512,"age":25},"osx":{"dis":512,"age":15},"win":{"dis":1024,"age":31}}</code>