如何在PHP中找到数组和该数组中元素的平均值之间的最小差异

你可以试试:

    <?php
$myArray = array(4,-18,78,136,-52,14,19,-35,162,71,19,-5,-134,77,-78,-35,19);
$averageArray = "";
//Average of the array
if(count($myArray) > 0) {
    $averageArray = array_sum($myArray)  / count($myArray);
}
$diff = array();
//Diff of average value and each value in a array named diff 
if(isset($myArray)) {
    foreach($myArray as $value) {
        $diff[] = abs($averageArray - $value);
    }
}
$key = array_search(min($diff),$diff);
echo "average = " . $averageArray .' - min value :'.min($diff).' - index:'.$key .' value: '.$myArray[$key]."'n";

第一步是将算法概念化。我想到的是:求平均值，求每个元素与平均值的绝对差值，然后求最小值。平均值可由总和和长度计算。

$avg = array_sum($array) / count($array);
$diff = function ($x) use ($avg) { return abs($x - $avg); };
$answer = min(array_map($diff, $array));

为了得到最接近平均值的元素，而不是仅仅映射到差值，我们可以保留原始元素。然后，当我们找到最小值时，我们只比较差异。

function minBy(callable $f, array $xs) {
  $min = $xs[0];
  foreach ($xs as $x) {
    if ($f($x, $min) < 0) $min = $x;
  }
  return $min;
}
$avg = array_sum($array) / count($array);
$diff = function ($x) use ($avg) { return array($x, abs($x - $avg)); };
$byDiff = function ($x,$y) { return $x[1] - $y[1]; };
$answer = minBy($byDiff, array_map($diff, $array));

要查找数组中元素的索引(注意，这可能不是唯一的)，您可以使用array_search .

粗糙但仍在工作:

<?php
$myArray = [4,-18,78,136,-52,14,19,-35,162,71,19,-5,-134,77,-78,-35,19];
// the average: sum/count
$average = round(array_sum($myArray) / count($myArray));
foreach ($myArray as $value) {
  $diffs[] = abs($average - $value);
}
asort($diffs);
print_r($diffs);
$d = reset($diffs);
$p = array_search($d, $diffs);
echo sprintf("Average: %s, min diff: %s, diff pos: %s'n", $average, $d, $p);