PHP merge arrays with identical key / values

Question

If Im looking to merge this PHP array into one into the lowest ID in array(1649). So that I would see only

  array:1 [
    1649 => array:2 [
      "firstName"   => "jack"
      "lastName"    => "straw"
      "mergedWith"  array:3 [
         "id" =>'1650'
         "id" =>'1651'
         "id" =>'1652'
      ]
    ]
  ]

Instead of this...

  array:4 [
    1649 => array:2 [
      "firstName" => "jack"
      "lastName" => "straw"
    ]
    1650 => array:2 [
      "firstName" => "jack"
      "lastName" => "straw"
    ]
    1651 => array:2 [
      "firstName" => "jack"
      "lastName" => "straw"
    ]
    1652 => array:2 [
      "firstName" => "jack"
      "lastName" => "straw"
     ]
  ]

I have a loop running that can pull out duplicates and find the lowest ID in the group, but not sure of the right way to collapse them into one.

The code I show are the results of a search that has identified id's with duplicate entries in those particular fields. I just want to further refine it to not delete, but add a field on the end of id 1649 that says mergedWith(1650,1651,1652)

Show the code that you have and explain how the result differs from what you want. — Patrick Q, Sep 20 '18 at 20:29
does the array always have the same values but with different keys? — mrbm, Sep 20 '18 at 20:30
Create an associative array that uses the firstname/lastname as the keys. Loop through this array. Add the element to the associative array if the key doesn't exist, otherwise update the `mergedWith` column with this element's index. — Barmar, Sep 20 '18 at 20:42
This might help you: https://stackoverflow.com/questions/307674/how-to-remove-duplicate-values-from-a-multi-dimensional-array-in-php — Salvatore Q Zeroastro, Sep 20 '18 at 20:43
You should really update your question to include the information you added in your latest comment. It's a totally different ask. — M. Eriksson, Sep 20 '18 at 20:44

Don't Panic · Accepted Answer · 2018-09-20T21:00:57.247

4

One way to do it is to group by first name and last name, and then reverse the grouping to get a single id. krsort the input beforehand to make sure you get the lowest id.

krsort($input);

//group
foreach ($input as $id => $person) {
    // overwrite the id each time, but since the input is sorted by id in descending order,
    // the last one will be the lowest id
    $names[$person['lastName']][$person['firstName']] = $id;
}

// ungroup to get the result
foreach ($names as $lastName => $firstNames) {
    foreach ($firstNames as $firstName => $id) {
        $result[$id] = ['firstName' => $firstName, 'lastName' => $lastName];
    }
}

Edit: not too much different based on your updated question. Just keep all the ids instead of a single one.

krsort($input);

foreach ($input as $id => $person) {
    //                   append instead of overwrite ↓ 
    $names[$person['lastName']][$person['firstName']][] = $id;
}
foreach ($names as $lastName => $firstNames) {
    foreach ($firstNames as $firstName => $ids) {
        // $ids is already in descending order based on the initial krsort
        $id = array_pop($ids);  // removes the last (lowest) id and returns it
        $result[$id] = [
            'firstName' => $firstName,
            'lastName' => $lastName,
            'merged_with' => implode(',', $ids)
        ];
    }
}

edited Sep 20 '18 at 21:00

answered Sep 20 '18 at 20:43

Don't Panic

39,820
10
58
75

Sorry for last minute change, as I started trying some things out i realized I needed notations on the merged accounts, not just to hide or delete them – weekapaug Sep 20 '18 at 20:54
1

@weekapaug It's okay as far as my answer is concerned, with this approach the code isn't much different either way. But be careful about modifying your question too much after asking. You really should avoid invalidating existing answers. – Don't Panic Sep 20 '18 at 20:55
Agreed, I have an issue where the tab key submits before I'm done, then I scramble to both try the answers and update all at once... – weekapaug Sep 20 '18 at 20:56
@weekapaug if you accidentally submit a question before you're ready, you can always quickly delete, make your edits, then undelete. – Don't Panic Sep 20 '18 at 20:58
I am working on my stack overflow etiquette, and appreciate the understanding – weekapaug Sep 20 '18 at 20:59

score 2 · Answer 2 · answered Sep 20 '18 at 21:06

ksort($resArr);
$tempArr = array_unique($resArr, SORT_REGULAR);
foreach ($tempArr as $key => $value) {
    foreach ($resArr as $key1 => $value2) {
        if($value['firstName'] == $value2['firstName'] && $value['lastName'] == $value2['lastName']) {
            $tempArr[$key]["mergedWith"][] = $key1;
        }
    }
}
print_r($tempArr);

$resArr = array(1650 => array(
        "firstName" => "jack",
        "lastName" => "straw"
    ),1649 => array(
        "firstName" => "jack",
        "lastName" => "straw"
    )
    ,
    1651 => array(
        "firstName" => "jack",
        "lastName" => "straw"
    ),
    1652 => array(
        "firstName" => "jack",
        "lastName" => "straw"
    ),
    1653 => array(
        "firstName" => "jack1",
        "lastName" => "straw"
    ),
    1654 => array(
        "firstName" => "jack1",
        "lastName" => "straw"
));

Output
Array
(
    [1649] => Array
        (
            [firstName] => jack
            [lastName] => straw
            [mergedWith] => Array
                (
                    [0] => 1649
                    [1] => 1650
                    [2] => 1651
                    [3] => 1652
                )

        )

    [1653] => Array
        (
            [firstName] => jack1
            [lastName] => straw
            [mergedWith] => Array
                (
                    [0] => 1653
                    [1] => 1654
                )

        )

)

PHP merge arrays with identical key / values

2 Answers2