php - 将一个数组缩减为另一个数组

Question

在 Laravel Blade 模板内，我试图减少这样的数组:

$longList = [['box' => 1, 'kg' => 2], ['box' => 2, 'kg' => 2], ['box' => 3, 'kg' => 3]];

变成这样的东西: $reducedList = [['count' => 2, 'kg' => 2], ['count' => 1, 'kg' => 3]];

这是我到目前为止所拥有的:

@php
          $variableWeights = isset($sale->variable_weight_json) ? collect(json_decode($sale->variable_weight_json, true)) : null;
          $groups = array();

          if (isset($variableWeights)) {
            $groups = $variableWeights->reduce(function($carry, $item) {
              $index = array_search($item['kg'], array_column($carry, 'weight'));
              if (isset($index)) {
                $existing = $carry[$index];
                array_splice($carry, $index, 1, [
                  'count' => $existing['count'] + 1,
                  'weight' => $item['kg']
                ]);
              } else {
                array_push($carry, [
                  'count' => 1,
                  'weight' => $item['kg'],
                ]);
              }
              return $carry;
            }, array());
          }
        @endphp

但它给了我错误 undefined offset :0

我是 php 新手。代码应该如何修正或者是否有更好的方法来达到预期的结果？

Answer 1

为什么不把它简化为像这样更简单的东西

$reducedList = [2 => 2, 3 => 1]

其中权重是索引，值是计数。

$reducedList = [];
foreach ($longList as $box) {
    if (isset($reducedList[$box['kg']]) {
        $reducedList[$box['kg']]++;
    } else {
        $reducedList[$box['kg']] = 1;
    }
}

这样您就可以避免复杂性，但仍然可以获得相同数量的信息。