Filter/Remove 在多维数组中多次找到列值的行

Question

我需要从输入数组中删除特定列中出现重复值的行。

示例数组：

$array = [
    ['user_id' => 82, 'ac_type' => 1],
    ['user_id' => 80, 'ac_type' => 5],
    ['user_id' => 76, 'ac_type' => 1],
    ['user_id' => 82, 'ac_type' => 1],
    ['user_id' => 80, 'ac_type' => 5]
];

我想按 user_id 进行筛选以确保唯一性并获得此结果：

所以，我的输出将是这样的：

[
    ['user_id' => 82, 'ac_type' => 1],
    ['user_id' => 80, 'ac_type' => 5],
    ['user_id' => 76, 'ac_type' => 1]
]

我已经尝试过：

$result = array_unique($array, SORT_REGULAR);

和

$result = array_map("unserialize", array_unique(array_map("serialize", $array)));

和

$result = array();
foreach ($array as $k => $v) {
    $results[implode($v)] = $v;
}
$results = array_values($results);
print_r($results);

但重复的行仍然存在。

Answer 1

花了我一段时间，但这应该有效（评论中的解释）：

<?php

/* Example array */
$result = array(
    0 => array(
        "user_id" => 82,
        "ac_type" => 1
        ),
    1 => array(
        "user_id" => 80,
        "ac_type" => 5
        ),
    2 => array(
        "user_id" => 76,
        "ac_type" => 1
        ),
    3 => array(
        "user_id" => 82,
        "ac_type" => 2
        ),
    4 => array(
        "user_id" => 80,
        "ac_type" => 2
        )
);

/* Function to get the keys of duplicate values */
function get_keys_for_duplicate_values($my_arr, $clean = false) {
    if ($clean) {
        return array_unique($my_arr);
    }

    $dups = $new_arr = array();
    foreach ($my_arr as $key => $val) {
      if (!isset($new_arr[$val])) {
         $new_arr[$val] = $key;
      } else {
        if (isset($dups[$val])) {
           $dups[$val][] = $key;
        } else {
           //$dups[$val] = array($key);
           $dups[] = $key;
           // Comment out the previous line, and uncomment the following line to
           // include the initial key in the dups array.
           // $dups[$val] = array($new_arr[$val], $key);
        }
      }
    }
    return $dups;
}

/* Create a new array with only the user_id values in it */
$userids = array_combine(array_keys($result), array_column($result, "user_id"));

/* Search for duplicate values in the newly created array and return their keys */
$dubs = get_keys_for_duplicate_values($userids);

/* Unset all the duplicate keys from the original array */
foreach($dubs as $key){
    unset($result[$key]);
}

/* Re-arrange the original array keys */
$result = array_values($result);

echo '<pre>';
print_r($result);
echo '</pre>';

?>

函数取自这个问题的答案：Get the keys for duplicate values in an array

输出：

Array
(
    [0] => Array
        (
            [user_id] => 82
            [ac_type] => 1
        )

    [1] => Array
        (
            [user_id] => 80
            [ac_type] => 5
        )

    [2] => Array
        (
            [user_id] => 76
            [ac_type] => 1
        )

)

Answer 2

经过测试和工作的示例。

<?php 

$details = array('0'=> array('user_id'=>'82', 'ac_type'=>'1'), '1'=> array('user_id'=>'80', 'ac_type'=>'5'), '2'=>array('user_id'=>'76', 'ac_type'=>'1'), '3'=>array('user_id'=>'82', 'ac_type'=>'1'), '4'=>array('user_id'=>'80', 'ac_type'=>'5'));

function unique_multidim_array($array, $key) { 
$temp_array = array(); 
$i = 0; 
$key_array = array(); 

foreach($array as $val) { 
    if (!in_array($val[$key], $key_array)) { 
        $key_array[$i] = $val[$key]; 
        $temp_array[$i] = $val; 
    } 
    $i++; 
    } 
  return $temp_array; 
 } 
?> 

<?php 
$details = unique_multidim_array($details,'user_id'); 
?> 

 <pre>

 <?php print_r($details); ?>

</pre>

将输出：

Array
(
[0] => Array
    (
        [user_id] => 82
        [ac_type] => 1
    )

[1] => Array
    (
        [user_id] => 80
        [ac_type] => 5
    )

[2] => Array
    (
        [user_id] => 76
        [ac_type] => 1
    )
)

取自此处 http://php.net/manual/en/function.array-unique.php 用户贡献的注释。

Answer 3

为了获得更清晰的“最小、完整、可验证的示例”，我将在我的演示中使用以下输入数组：

$array = [
    ['user_id' => 82, 'ac_type' => 1],
    ['user_id' => 80, 'ac_type' => 5],
    ['user_id' => 76, 'ac_type' => 1],
    ['user_id' => 82, 'ac_type' => 2],
    ['user_id' => 80, 'ac_type' => 5]
];
// elements [0] and [3] have the same user_id, but different ac_type
// elements [1] and [4] have identical row data

无条件地将行推入结果数组并分配关联的一级键，然后使用 array_values() 重新索引。此方法用较晚出现的行覆盖较早的重复行。

array_column demo:

var_export(array_values(array_column($array, null, 'user_id')));

foreach demo:

$result = [];
foreach ($array as $row) {
    $result[$row['user_id']] = $row;
}
var_export(array_values($result));

输出：

[
    ['user_id' => 82, 'ac_type' => 2], // was input row [3]
    ['user_id' => 80, 'ac_type' => 5], // was input row [4]
    ['user_id' => 76, 'ac_type' => 1]  // was input row [2]
]

使用条件或空合并赋值运算符在删除重复项时保留第一个出现的行。

foreach null coalescing assignment demo:

foreach ($array as $a) {
    $result[$a['user_id']] ??= $a; // only store if first occurrence of user_id
}
var_export(array_values($result)); // re-index and print

foreach isset demo:

foreach ($array as $a) {
    if (!isset($result[$a['user_id']])) {
        $result[$a['user_id']] = $a; // only store if first occurrence of user_id
    }
}
var_export(array_values($result)); // re-index and print

输出：

[
    ['user_id' => 82, 'ac_type' => 1], // was input row [0]
    ['user_id' => 80, 'ac_type' => 5], // was input row [1]
    ['user_id' => 76, 'ac_type' => 1]  // was input row [2]
]

也可以无条件推送数据并避免某个条件，但输入和输出之间的行顺序可能不同（如果这对您很重要）。

array_reverse, array_column demo:

var_export(array_values(array_column(array_reverse($array), null, 'user_id')));

array_reduce demo:

var_export(
    array_values(
        array_reduce(
            $array,
            fn($res, $row) => array_replace([$row['user_id'] => $row], $res),
            []
        )
    )
);

foreach array_reverse demo:

$result = [];
foreach (array_reverse($array) as $row) {
    $result[$row['user_id']] = $row;
}
var_export(array_values($result));

输出：

[
    ['user_id' => 80, 'ac_type' => 5], // was input row [1]
    ['user_id' => 82, 'ac_type' => 1], // was input row [0]
    ['user_id' => 76, 'ac_type' => 1]  // was input row [2]
]

^{有关此示例中未表达的边缘情况的警告：如果您使用行值作为标识符，这些标识符在用作键时可能会损坏，则上述技术将产生不可靠的结果。例如，PHP 不允许浮点值作为键（它们会导致错误或被截断，具体取决于您的 PHP 版本）。只有在这些边缘情况下，您才会考虑使用低效的迭代调用 in_array() 来评估唯一性。}

仅当通过整行数据确定唯一性时才适合使用 array_unique(..., SORT_REGULAR)。

array_unique demo:

var_export(array_unique($array, SORT_REGULAR));

输出：

[
    ['user_id' => 82, 'ac_type' => 1], // was input row [0]
    ['user_id' => 80, 'ac_type' => 5], // was input row [1]
    ['user_id' => 76, 'ac_type' => 1]  // was input row [2]
    ['user_id' => 82, 'ac_type' => 2], // was input row [3]
]

Answer 4

$array = [
    ['user_id'=>82,'ac_type'=>1],
    ['user_id'=>80,'ac_type'=>5],
    ['user_id'=>76,'ac_type'=>1],
    ['user_id'=>82,'ac_type'=>2],
    ['user_id'=>80,'ac_type'=>6]
];

$array = array_reverse($array);

$v = array_reverse( 
    array_values( 
        array_combine( 
            array_column($array, 'user_id'),
            $array
        )
    )
);


echo '<pre>';
var_dump($v);

结果：

array(3) {
  [0]=>
  array(2) {
    ["user_id"]=>
    int(76)
    ["ac_type"]=>
    int(1)
  }
  [1]=>
  array(2) {
    ["user_id"]=>
    int(82)
    ["ac_type"]=>
    int(1)
  }
  [2]=>
  array(2) {
    ["user_id"]=>
    int(80)
    ["ac_type"]=>
    int(5)
  }
}

Filter/Remove 在多维数组中多次找到列值的行

Filter/Remove rows where column value is found more than once in a multidimensional array

php

filtering

unique

duplicates

multidimensional-array