如何使用PHP和Javascript在列表中获取相同的值

Question

I get a list from a table in my database. It contains latitude and longitude. I want to show these makers on Google Map. So here is what i did:

<?php
        $exe1 = "SELECT * FROM accident";
        $result1 = mysql_query($exe1, $db) or die(mysql_error());
        $location = array();


        while ($row = mysql_fetch_array($result1)) {
            if ($row["latitude"] != "NA") {
                $location[] = array(
                    $row["latitude"],
                    $row["longitude"],

                );
            } 
            }

    ?>   

Then i using JavaScript to get these geo code and push to markers:

for (var i = 0; i < locations.length; i++) {

    lat = locations[i][0];
    lng = locations[i][1];
    }

Because there are so many locations in my table, some of them are have exact same latitude and longitude. I want to show these markers which contain same lat and lng. Anyone know how to do? Appreiciate any help from you!

Answer 1

If you want to make only one same location to show;

    $location = array();
    $hit = array();
    while ($row = mysql_fetch_array($result1)) {
        if ($row["latitude"] != "NA") {
            $lat = $row["latitude"];
            $lng = $row["longitude"];
            $key = $lat . '_' . $lng;
            $location[$key] = array($lat, $lng);
            $hit[$key]++;
        } 
    }

    $list = array();
    foreach ($hit as $key => $num) {
        if ($num > 1 ) {
            $list[] = $location[$key];
        }
    }

If you want to make all the same location to show, you can do it like this:

    $location = array();
    $hit = array();
    while ($row = mysql_fetch_array($result1)) {
        if ($row["latitude"] != "NA") {
            $lat = $row["latitude"];
            $lng = $row["longitude"];
            $key = $lat . '_' . $lng;
            $location[$key][] = array($lat, $lng);
            $hit[$key]++;
        } 
    }

    $list = array();
    foreach ($hit as $key => $num) {
        if ($num > 1 ) {
            $list = array_merge($list, $location[$key]);
        }
    }