<?php $list = [ [ 'create_at' => '2023-01-02', 'currency_type' => 'ONE', 'settlement' => 3 ], [ 'create_at' => '2023-01-27', 'currency_type' => 'ONE', 'settlement' => 5 ], [ 'create_at' => '2023-01-02', 'currency_type' => 'TWO', 'settlement' => 4 ], [ 'create_at' => '2023-03-02', 'currency_type' => 'ONE', 'settlement' => 7 ], [ 'create_at' => '2023-05-02', 'currency_type' => 'ONE', 'settlement' => 6 ], ]; $new_list = [ 'ONE' => [ [ 'time' => '2022-12', 'settlement' => 0 ], [ 'time' => '2023-01', 'settlement' => 8 ], [ 'time' => '2023-02', 'settlement' => 7 ], [ 'time' => '2023-03', 'settlement' => 0 ], [ 'time' => '2023-04', 'settlement' => 0 ], [ 'time' => '2023-05', 'settlement' => 6 ], ], 'TWO' => [ [ 'time' => '2022-12', 'settlement' => 0 ], [ 'time' => '2023-01', 'settlement' => 4 ], [ 'time' => '2023-02', 'settlement' => 0 ], [ 'time' => '2023-03', 'settlement' => 0 ], [ 'time' => '2023-04', 'settlement' => 0 ], [ 'time' => '2023-05', 'settlement' => 0 ] ], ]; 如何将$list变成$new_list？规则是按currency_type分组，同一月份settlement求和，time为最近半年时间

可以按照以下步骤将$list变成$new_list：

1. 定义一个空数组$grouped_list用来存储按currency_type分组后的数据。

2. 遍历$list数组，将每个元素按currency_type分组存储到$grouped_list数组中。

3. 遍历$grouped_list数组，对于每个currency_type，按照时间顺序生成半年内的时间段，初始化一个空数组$monthly_data用来存储该时间段内的数据，并将其存储到$new_list数组中对应currency_type的位置。

4. 遍历$grouped_list数组中每个currency_type的数据，将数据按照时间分组到$monthly_data数组对应的时间段中，并对每个时间段内的settlement求和，更新$monthly_data数组。

5. 将$monthly_data数组中的数据存储到$new_list数组中对应currency_type的位置。

下面是代码实现：

$new_list = [];
$grouped_list = [];

// 按currency_type分组
foreach ($list as $item) {
    $currency_type = $item['currency_type'];
    if (!isset($grouped_list[$currency_type])) {
        $grouped_list[$currency_type] = [];
    }
    $grouped_list[$currency_type][] = $item;
}

// 处理每个currency_type
foreach ($grouped_list as $currency_type => $data) {
    // 初始化时间段数据
    $six_months_ago = strtotime('-6 months');
    $monthly_data = [];
    for ($i = 0; $i < 6; $i++) {
        $time = date('Y-m', strtotime("+$i months", $six_months_ago));
        $monthly_data[$time] = [
            'time' => $time,
            'settlement' => 0,
        ];
    }

    // 按时间分组，求和
    foreach ($data as $item) {
        $time = date('Y-m', strtotime($item['create_at']));
        if (isset($monthly_data[$time])) {
            $monthly_data[$time]['settlement'] += $item['settlement'];
        }
    }

    // 存储到$new_list中
    $new_list[$currency_type] = array_values($monthly_data);
}