如何相互置换两个数组键

Question

如何将一个数组中的每个值与另一个数组组合以创建一个结构，该结构将成为 table 的来源。例如，我们有数组：

$a = array(
  'animal' => ['horse', 'donkey', 'elephant'],
  'food' => ['grass', 'hay', 'acorn'],
);

And the effect I need is:

$result = array(
  'horse' = array(
    'grass' => [ 'animal' => 'horse', 'food' => 'grass'],
    'hay' => [ 'animal' => 'horse', 'food' => 'hay'],
    'acorn' => [ 'animal' => 'horse', 'food' => 'acorn'],
  },
  'donkey' = array(
    'grass' => [ 'animal' => 'donkey', 'food' => 'grass'],
    'hay' => [ 'animal' => 'donkey', 'food' => 'hay'],
    'acorn' => [ 'animal' => 'donkey', 'food' => 'acorn'],
  },
  'elephant' = array(
    'grass' => [ 'animal' => 'elephant', 'food' => 'grass'],
    'hay' => [ 'animal' => 'elephant', 'food' => 'hay'],
    'acorn' => [ 'animal' => 'elephant', 'food' => 'acorn'],
  },
);

但我的问题是是否可以将算法泛化到任意高维度。

Answer 1

就算法而言，我会说自己尝试一些东西。

也就是说，我建议从嵌套的 foreach 循环开始：

$result = array();

foreach ($a['animal'] as $val) {
    $result[$val] = array();
    foreach ($a['food'] as $val2) {
        $result[$val][$val2] = array('animal' => $val, 'food' => $val2);
    }
}

然后可能将此代码扩展为 modular/customizable。

如何相互置换两个数组键

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