Compare two multidimensional arrays then create array of only unique

Question

I've been trying to get this for hours now.

I have two multidimensional arrays

    $newData (
    [0] => Array(
        [id] => 1
        [name] => John
        [sex] => male
    )
    [1] => Array(
        [id] => 2
        [name] => Kenny
        [sex] => male
    )
    [2] => Array(
        [id] => 3
        [name] => Sarah
        [sex] => female
    )
    [3] => Array(
        [id] => 4
        [name] => George
        [sex] => male
    )
)

$oldData (
    [0] => Array(
        [id] => 3
        [name] => Sarah
        [sex] => female
    )
    [1] => Array(
        [id] => 4
        [name] => George
        [sex] => male
    )
    [2] => Array(
        [id] => 5
        [name] => Peter
        [sex] => male
    )
    [3] => Array(
        [id] => 6
        [name] => Lexi
        [sex] => female
    )
)

I need to compare $newData and $oldData and grab only the new data that is before the first common array.

My $newData will then be:

$newData (
[0] => Array(
    [id] => 1
    [name] => John
    [sex] => male
)
[1] => Array(
    [id] => 2
    [name] => Kenny
    [sex] => male
)

)

I've tried everything from array_unique, if comparing the ID keys but nothing is working properly.

Do I need to merge them, first? map them? Bahh, I have no idea, I am so lost.

Any help would be awesome

Ram Sharma · Accepted Answer · 2015-08-18 09:47:45Z

8

I would just do a nested foreach loop. I don't know which programming language You're using, but assuming that it's PHP ($):

$tmpArray = array();

foreach($newData as $data1) {

  $duplicate = false;
  foreach($oldData as $data2) {
    if($data1['id'] === $data2['id'] && $data1['name'] === $data2['name'] && $data1['sex'] === $data2['sex']) $duplicate = true;
  }

  if($duplicate === false) $tmpArray[] = $data1;
}

You then have the desired array in the $tmpArray variable. You can make of course $newData = $tmpArray; afterwards.

edited Aug 18, 2015 at 9:47

Ram Sharma

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answered Apr 21, 2013 at 19:55

Maxim Zubarev

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3 Comments

Ryan Over a year ago

by copying your code, then changing the key names to what I currently have, it returns an empty array when I print_r $tmpArray

Maxim Zubarev Over a year ago

then You obviously mistyped something. If I try this code here pastebin.com/jJgDvLxE I get exactly the array which You wanted as a result...

Ryan Over a year ago

I might of, but I just rebuilt the code so if was easier to read for me. regardless, it works, and you just saved me from pulling all my hair out. I was way way WAY overthinking this.

Michal Rus · Accepted Answer · 2013-04-21 22:20:37Z

1

Just iterate over $newData until you find the first element from $oldData?

$cmp = $oldData[0];
$data = array();
foreach ($newData as $el) {
    if ($el['id'] === $cmp['id']
      && $el['name'] === $cmp['name']
      && $el['sex'] === $cmp['sex'])
        break;
    $data[] = $el;
}

Your new data will be stored in $data.

edited Apr 21, 2013 at 22:20

answered Apr 21, 2013 at 19:56

Michal Rus

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Comments

Community · Accepted Answer · 2017-05-23 11:54:22Z

0

How about using this? By modifying thelamborghinistory's answer,

Unset the dynamic key if there is a duplicate.

public function removeDuplicate($oldData, $newData, $key)
{
    $tmpArray = array();
    foreach ($newData as $data1) {
        $duplicate = false;
        foreach ($oldData as $data2k => $data2v) {
            if ($data1[$key] === $data2v[$key]) {
                unset($newData[$data2k]);
                $duplicate = true;
            }
        }
        if ($duplicate === true) {
            $tmpArray[] = $data1;
        } else {
            $tmpArray[] = $data1;
        }
    }
    return $tmpArray;
}

And then you have to just call,

removeDuplicate($oldData, $newData, 'name');//or whatever you want

edited May 23, 2017 at 11:54

CommunityBot

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answered Oct 21, 2016 at 6:41

Keyur

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