Question

我有两个坐标值。我正在计算每个坐标的欧几里德距离。我想在这里申请K-最近邻居算法。

每个坐标与其他所有点的欧几里德距离

选择最接近最大点的点（从所有点开始，选择最接近最大坐标数的点）

    $result2 = mysqli_query($con,"SELECT pcount, ncount from test");
    $result1 = mysqli_query($con,"SELECT pcount, ncount from test");
    $i = 0;
                $k = 0;
    $min = 0;
    while ($row1 = @mysqli_fetch_array($result1))
    {
        $pcount = $row1['pcount'];
        $ncount = $row1['ncount'];
        echo "pcount is $pcount<br/>";
        echo "ncount is $ncount<br/></br>";
        $a[$i] = $pcount ;
        $b[$i] = $pcount ;
        $j = 0;
        $result2 = mysqli_query($con,"SELECT pcount, ncount from test");
        while ($row2 = @mysqli_fetch_array($result2))
        {
        //echo "j is $j <br/>";
        $a[$j] = $row2['pcount'];   
        $b[$j] = $row2['ncount'];
        $diff = ($a[$i] - $a[$j])^2 + ($b[$i] - $b[$j])^2;
        if( $diff != 0)
            $diff = sqrt( $diff );
            $j= $j + 1;
            echo "$diff <br>";
                        arr[$k] = $diff;
                        $k = $k + 1;
        }               
        //echo "i is $i <br/>";
            $i = $i + 1;    
    }

此处，arr[$k]包含所有点的距离差异。如何获得最接近其他最大点的点数。可能有超过1个这样的点。

Answer 1

我建议使用以下方法。

0）将db数据提取到2d数组中如下所示：

array(
    array($x1,$y1),
    array($x2,$y2),
    ...
)

1）构建数据，存储每个点到所有其他点的（方形）距离之和。

2）找到该数组中的最低值（最小值）。

3）获取具有该值的所有积分。

所以代码应如下所示：

// $a_points = array( array($x1,$y1), array($x2,$y2), ... ); // array of point coordinates

$a_sum_dists = array();
foreach ($a_points as $i => $pt1) {
    list($x1, $y1) = $pt1;
    $sum = 0;
    foreach ($a_points as $j => $pt2) {
        if ($j == $i) continue;
        list($x2, $y2) = $pt2;
        $sum += pow($x2- $x1, 2) + pow($y2- $y1, 2);
    }
    $a_sum_dists[$i] = $sum;
}
$min_sum = min($a_sum_dists);
$a_result_points = array_intersect_key(
    $a_points, 
    array_filter($a_sum_dists, function ($v) use ($min_sum) {
        return $v == $min_sum;
    })
);

Demo

处理复杂的数据结构值

1 个答案: