按列值对数据行进行分组并重组为关联的多维数组

Question

我正在尝试将数组的索引数组更改为新的数组结构。我的数据如下：

$arr = array( 
     array( "year" => 1921, "name" => "bob" ),
     array( "year" => 1944, "name" => "steve" ),
     array( "year" => 1944, "name" => "doug" ),
     array( "year" => 1921, "name" => "jim" ),
);

我想重新创建一个将它们分组到同一年的新数组。我能想到的最好方法是将年份指定为键，这样任何包含该年份的行都会添加到该键，但这不是我要查找的输出。我需要的是下面列出的方式。

"data": [
    {
       "year":"1921",
       "names": [ 
            { "name":"bob" }, { "name":"jim"} 
        ]
    },
    {
        "year":1944",
        "names": [
            { "name":"steve" }, { "name":"doug "} 
        ]
    }

Answer 1

您不需要 pre-extract 唯一年份，也不需要在嵌套循环中使用条件。 只需使用临时 [=24= 将数据推入结果集中] 键，然后在完成循环后删除临时键。

这确保了唯一的年份，但允许重复名称。

代码：(Demo)

$arr = [
     ["year" => 1921, "name" => "bob"],
     ["year" => 1944, "name" => "steve"],
     ["year" => 1944, "name" => "doug"],
     ["year" => 1921, "name" => "jim"],
];

foreach ($arr as $item) {
    $result[$item['year']]['year'] = $item['year'];
    $result[$item['year']]['names'][] = ['name' => $item['name']];
}

echo json_encode(
         ['data' => array_values($result)],
         JSON_PRETTY_PRINT // for better visualization
);

输出：

{
    "data": [
        {
            "year": 1921,
            "names": [
                {
                    "name": "bob"
                },
                {
                    "name": "jim"
                }
            ]
        },
        {
            "year": 1944,
            "names": [
                {
                    "name": "steve"
                },
                {
                    "name": "doug"
                }
            ]
        }
    ]
}

按列值对数据行进行分组并重组为关联的多维数组

Group rows of data by a column value and restructure into an associative multi-dimensionsl array

php

arrays

grouping

associative-array

multidimensional-array