如何查找和删除php数组中几乎重复的行，这些行在一个键值上有所不同？

Question

我有以下阵列（阵列大）：

Array ( 
    [0] => Array ( 
       [id] => 1 
       [timestamp] => 1503050400 
       [name] => Event A 
       [value] => ) 
    [1] => Array ( 
       [id] => 2 
       [timestamp] => 1503446400 
       [name] => Event B 
       [value] => ) 
    [2] => Array ( 
       [id] => 2 
       [timestamp] => 1503446400 
       [name] => Event B 
       [value] => 71) 
    [3] => Array ( 
       [id] => 3 
       [timestamp] => 1503720000 
       [name] => Event C 
       [value] => 12) 
    [4] => Array ( 
       [id] => 3 
       [timestamp] => 1503720000 
       [name] => Event C 
       [value] => ) 

       ... 
) 

正如你可以看到，一些阵列键（行）具有相同的ID，时间戳和名称，但不同的价值。 我想找到并取消设置满足以下条件的行（$ array [$ key]）：

如果数组的键具有相同的名称，Id和时间戳，请删除此键，但只保留Value！ = NULL

看起来像这样：

foreach ($array as $key => $row) { 
    if (...) { 
    unset($array[$key]); 
    } 
else {} 

} 
print_r($array); 

输出应该是：

Array ( 
    [0] => Array ( 
       [id] => 1 
       [timestamp] => 1503050400 
       [name] => Event A 
       [value] => ) 
    [2] => Array ( 
       [id] => 2 
       [timestamp] => 1503446400 
       [name] => Event B 
       [value] => 71) 
    [3] => Array ( 
       [id] => 3 
       [timestamp] => 1503720000 
       [name] => Event C 
       [value] => 12) 

       ... 
) 

Answer 1

可以使用array_reduce()和array_filter()：

<?php 

$data = array(
    array(
     'id' => 1, 
     'timestamp' => 1503050400, 
     'name' => 'Event A', 
     'value' => null, 
    ), 
    array(
     'id' => 2, 
     'timestamp' => 1503446400, 
     'name' => 'Event B', 
     'value' => null, 
    ), 
    array(
     'id' => 2, 
     'timestamp' => 1503446400, 
     'name' => 'Event B', 
     'value' => 71, 
    ), 
    array(
     'id' => 3, 
     'timestamp' => 1503720000, 
     'name' => 'Event C', 
     'value' => 12, 
    ), 
    array(
     'id' => 3, 
     'timestamp' => 1503720000, 
     'name' => 'Event C', 
     'value' => null, 
    ), 
); 

/** 
* Reduce the array of items to an array of buckets, where 
* each bucket contains elements with the same 
* 
* - id 
* - timestamp 
* - name 
* 
* so that we can than take a look at the contents of the 
* individual buckets. 
*/ 
$buckets = array_reduce(
    $data, 
    function (array $carry, array $item) { 
     /** 
     * create an index from 
     * 
     * - id 
     * - timestamp 
     * - name 
     */ 
     $index = serialize(array(
      'id' => $item['id'], 
      'timestamp' => $item['timestamp'], 
      'name' => $item['name'], 
     )); 

     /** 
     * initialize empty bucket if we don't have one yet for this index 
     */ 
     if (!array_key_exists($index, $carry)) { 
      $carry[$index] = array(); 
     } 

     /** 
     * add item to bucket 
     */ 
     $carry[$index][] = $item; 

     return $carry; 
    }, 
    array() 
); 

/** 
* Reduce the content of the buckets to elements that match the requirements. 
*/ 
$filtered = array_reduce(
    $buckets, 
    function (array $carry, array $items) { 
     /** 
     * if we have only one item in the bucket, let's take it 
     */ 
     if (1 === count($items)) { 
      $carry[] = array_shift($items); 

      return $carry; 
     } 

     /** 
     * find all items where the value is not null 
     */ 
     $withoutNullValue = array_filter($items, function (array $item) { 
      return array_key_exists('value', $item) && null !== $item['value']; 
     }); 

     /** 
     * if we have any items where the value is not null, take all of them 
     */ 
     if (0 < count($withoutNullValue)) { 
      $carry = array_merge(
       $carry, 
       $withoutNullValue 
      ); 

      return $carry; 
     } 

     /** 
     * if all of the items have a value of null, let's just take the first 
     */ 
     $carry[] = array_shift($items); 

     return $carry; 
    }, 
    array() 
); 

var_dump($filtered); 

为了参考，见：

• http://php.net/manual/en/function.array-reduce.php
• http://php.net/manual/en/function.array-filter.php

有关示例，请参见：

• https://3v4l.org/Toq75

Answer 2

foreach ($array as $key => $row) { 
    if ($row[value]) { 
    unset($array[$key]); 
    } 
else { 
    $row[result] = $row[value]; 
    unset($row[value]); 
    } 
} 
print_r($array);