PHP多维数组操作与聚合分析
PHP多维数组操作与聚合分析
PHP的数组可以嵌套任意维度。多维数组在处理复杂数据结构时很有用。今天说说多维数组的常用操作。
创建和访问多维数组。
```php
$data = [
'users' => [
['id' => 1, 'name' => '张三', 'scores' => [85, 92, 78]],
['id' => 2, 'name' => '李四', 'scores' => [90, 88, 95]],
],
];
echo $data['users'][0]['name'] . "\n";
echo $data['users'][0]['scores'][0] . "\n";
// 添加数据
$data['users'][] = ['id' => 3, 'name' => '王五', 'scores' => [70, 75, 80]];
?>
array_column提取特定列。
```php
$users = [
['id' => 1, 'name' => '张三', 'age' => 28],
['id' => 2, 'name' => '李四', 'age' => 35],
['id' => 3, 'name' => '王五', 'age' => 22],
];
$names = array_column($users, 'name');
print_r($names);
$nameMap = array_column($users, 'name', 'id');
print_r($nameMap);
?>
array_map批量处理。
```php
$prices = [100, 200, 300];
$quantities = [2, 3, 1];
$totals = array_map(fn($p, $q) => $p * $q, $prices, $quantities);
print_r($totals);
?>
array_filter过滤。
```php
$numbers = [1, 2, 3, 4, 5, 6];
$evens = array_filter($numbers, fn($n) => $n % 2 === 0);
print_r($evens);
$filtered = array_filter($users, fn($u) => $u['age'] > 25);
print_r($filtered);
?>
array_reduce聚合。
```php
$orderAmounts = [100, 250, 80, 450, 200];
$total = array_reduce($orderAmounts, fn($c, $v) => $c + $v, 0);
echo "总计: $total\n";
$items = [
['id' => 1, 'amount' => 100, 'status' => 'paid'],
['id' => 2, 'amount' => 250, 'status' => 'pending'],
['id' => 3, 'amount' => 80, 'status' => 'paid'],
];
$stats = array_reduce($items, function ($carry, $item) {
$carry[$item['status']] = ($carry[$item['status']] ?? 0) + 1;
return $carry;
}, []);
print_r($stats);
?>
多维数组排序。
```php
$products = [
['name' => '商品A', 'price' => 100, 'sales' => 50],
['name' => '商品B', 'price' => 200, 'sales' => 30],
['name' => '商品C', 'price' => 150, 'sales' => 80],
];
usort($products, fn($a, $b) => $b['sales'] <=> $a['sales']);
print_r($products);
// 多字段排序
usort($products, function ($a, $b) {
if ($a['sales'] === $b['sales']) return $a['price'] <=> $b['price'];
return $b['sales'] <=> $a['sales'];
});
?>
PHP的数组函数有两百多个，常用的就二三十个。array_map、array_filter、array_reduce是最强大的三个函数。array_column、array_chunk、array_slice在数据分片时很有用。用好这些函数，很多需要写循环的场景一行代码就搞定了