识别和收集多维数组中的潜在重复项

Question

我有一个类似下面的数组，我想在其中识别重复项；

$names = array(
    array("Name" => "John Smith",      "ID" => 65), 
    array("Name" => "Richard Johnson", "ID" => 96), 
    array("Name" => "John Smith",      "ID" => 1105),
    ...
)

有很多类似的问题，但大多数只涉及在存在重复项时返回真/假值，或者只是删除重复项。如果有与此问题相同的问题，我深表歉意，我查看但找不到适合我情况的问题。

我只想识别一对包含相同“名称”值但可能不同“ID”值的数组。我知道这可能会导致重复值的结果重复，但我想我可以自己解决这个问题。我不想删除重复的值，我只想识别它们。

理想情况下，它会返回一个类似于以下（或类似）的数组；

$dupes = array(
    array(
        array("Name" => John Smith, "ID" => 65),
        array("Name" => John Smith, "ID" => 1105)
    )
)

然后我可以将其处理成更精致和用户友好的数组。

我正在考虑使用递归 in_array 函数，或者可能是第二个工作数组。有什么想法吗？

Answer 1

您为什么不直接循环并使用名称作为键创建一个新数组？在此处测试以下内容：http://phptester.net/

$names = array(
    array("Name" => 'John Smith', "ID" => 65), 
    array("Name" => 'Richard Johnson', "ID" => 96), 
    array("Name" => 'John Smith', "ID" => 1105)
);

$users = [];
foreach($names as $usersArray){
    
    $users[$usersArray['Name']]['ids'][] = $usersArray['ID'];
    
}

print_r($users);

或者简单地说：

$names = array(
    array("Name" => 'John Smith', "ID" => 65), 
    array("Name" => 'Richard Johnson', "ID" => 96), 
    array("Name" => 'John Smith', "ID" => 1105)
);

$users = [];
foreach($names as $usersArray){
    
    $users[$usersArray['Name']][] = $usersArray['ID'];
    
}

print_r($users);

Answer 2

对于这种情况，您通常需要定义一些逻辑，以根据记录中的值创建哈希以确定相等性。定义好之后，您可以使用简单的循环和关联数组来跟踪哪些记录有重复。

<?php
/**
 * Define an algorithm for equality between records.
 *
 * @param $record
 * @return string
 */
function generateHashForUserRecord($record)
{
    return sha1($record['Name']);
}

$names = [
    ['Name' => 'John Smith', 'ID' => 65],
    ['Name' => 'Richard Johnson', 'ID' => 96],
    ['Name' => 'John Smith', 'ID' => 1105]
];

// This map will be an populated with all records, keyed by hash
$hashBuffer = [];

// Buffer for hashes that are associated with more than one record
$duplicateHashes = [];

// This will be populated with the duplicate records
$duplicateRecords = [];

// Iterate through all of the records
foreach($names as $currRecord)
{
    // Generate a has for the record
    $currHash = generateHashForUserRecord($currRecord);

    // If the hash is not in the hashtable yet, create an array to hold entries with this hash
    if(!array_key_exists($currHash, $hashBuffer))
    {
        $hashBuffer[$currHash] = [];
    }
    else // If this hash is already in the buffer, we have a duplicate - add it to the  $duplicateHashes array
    {
        $duplicateHashes[$hash] = $currHash;
    }

    // Add the record to the hash buffer
    $hashBuffer[$currHash][] = $currRecord;
}

foreach($duplicateHashes as $currDuplicateHash)
{
    $duplicateRecords = array_merge($duplicateRecords, $hashBuffer[$currDuplicateHash]);
}

print_r($duplicateRecords);

这是很多丑陋的过程代码，所以将它封装在某种帮助类中可能是个好主意。

<?php

$names = [
    ['Name' => 'John Smith', 'ID' => 65],
    ['Name' => 'Richard Johnson', 'ID' => 96],
    ['Name' => 'John Smith', 'ID' => 1105]
];

$duplicateRecords = UserRecordHelper::getDuplicateRecords($names);

print_r($duplicateRecords);

class UserRecordHelper
{
    public static function getDuplicateRecords($records)
    {
        // This map will be an populated with all records, keyed by hash
        $hashBuffer = [];

        // Buffer for hashes that are associated with more than one record
        $duplicateHashes = [];

        // This will be populated with the duplicate records
        $duplicateRecords = [];


        // Iterate through all of the records
        foreach ($records as $currRecord)
        {
            // Generate a has for the record
            $currHash = self::generateHashForUserRecord($currRecord);

            // If the hash is not in the hashtable yet, create an array to hold entries with this hash
            if (!array_key_exists($currHash, $hashBuffer))
            {
                $hashBuffer[$currHash] = [];
            }
            else // If this hash is already in the buffer, we have a duplicate - add it to the  $duplicateHashes array
            {
                $duplicateHashes[$hash] = $currHash;
            }

            // Add the record to the hash buffer
            $hashBuffer[$currHash][] = $currRecord;
        }

        foreach ($duplicateHashes as $currDuplicateHash)
        {
            $duplicateRecords = array_merge($duplicateRecords, $hashBuffer[$currDuplicateHash]);
        }

        return $duplicateRecords;
    }

    public static function generateHashForUserRecord($record)
    {
        return sha1($record['Name']);
    }
}