Group Values of Array According to Similar Keys - PHP

Question

I have an array that looks like the following:

$myArray = 
[
  ['email' => 'email1@email.com', 'value' => '123'],
  ['email' => 'email1@email.com', 'value' => '456'],
  ['email' => 'email1@email.com', 'value' => '789'],
  ['email' => 'email2@email2.com', 'value' => '123'],
  ['email' => 'email2@email2.com', 'value' => '456'],
  ...
]

What is a good way to combine the values according to unique keys (email) such that the previous array would end up like so:

[
  'email@email.com' => ['123', '456'],
  'email2@email2.com' => ['123', '456', '789'],
  ...
]

I can think of solutions, but they all seem quite inefficient :( Here is one for example:

$resultArray = array();
foreach ($myArray as $info) {
    if (!isset($resultArray[$info['email']])) {
        $resultArray[$info['email']] = array();
    }
    array_push($resultArray[$info['email']], $info['value']);
}

This doesn't sit well with me for some reason.

QUESTION

Are there better solutions?

-- Updated my Blatant Mistake - Check new (1st) array :/ --

I'm not sure what you're getting at, @Rizier123. I don't think I do... nor do I want to... — karns, Jun 09 '15 at 12:27
My point is to keep only the unique keys, but aggregate their values. — karns, Jun 09 '15 at 12:28
@b0s3 - It is actually generated in a previous step from a SQL result. However, I am not majorly concerned about that. — karns, Jun 09 '15 at 12:28
@karns If you have 2 elements with the same key your array will only have 1 element — Rizier123, Jun 09 '15 at 12:30
I agree with @Rizier123... It is possible same key in multidimensional array only — Deep Kakkar, Jun 09 '15 at 12:31
The above array is not possible http://stackoverflow.com/questions/30636179/how-does-php-index-associative-arrays/30636430#30636430 — Narendrasingh Sisodia, Jun 09 '15 at 12:32
@Rizier123 - Please read through my question more thoroughly and let me know how I could make it clearer. I know that I can't have duplicate keys. — karns, Jun 09 '15 at 12:32
@Uchiha - It is indeed possible. Notice how I don't have keys that collide. I have "email..." and "email2..." — karns, Jun 09 '15 at 12:33
Oh! My apologies everyone, the first array is incorrect * I was thinking you were talking about the answer.. Let me update the question :/ — karns, Jun 09 '15 at 12:35
@karns *I know that I can't have duplicate keys* There is your first problem. How do you want to combine all elements with the same key if they can't exist ? — Rizier123, Jun 09 '15 at 12:35
@karns *the first array is incorrect* Are you serious right now?! — Rizier123, Jun 09 '15 at 12:44
@Rizier123 - I am. Am I screwed in the head? It must be too early for me. What is the issue with it if they are nested arrays now? — karns, Jun 09 '15 at 12:46
@karns Now nothing is wrong anymore... And I look like a fool which fell for the trap. (Your code is good and works, I don't think you can write it much better than that; Besides the typo with the dollar sign in your index) — Rizier123, Jun 09 '15 at 12:47
@Rizier123 - Thank you, I appreciate your patience with my ingorance :P I hope at the very least people got entertainment out of this. What do people think - should I remove this question? — karns, Jun 09 '15 at 12:50
@karns It's up to you, but I think you can go with this code which you already have (if you fix the dollar sign typo). — Rizier123, Jun 09 '15 at 12:54
`foreach ($myArray as $item) { $newArray[$item['email']][] = $item['value']; }`. [Example here](http://ideone.com/v4WE0g). — Phylogenesis, Jun 09 '15 at 12:55

score 2 · Accepted Answer · answered Jun 09 '15 at 13:08

2

All your checks and uses of array_push() can be replaced by the empty array indexer. This greatly simplifies your loop as follows:

foreach ($myArray as $item) {
    $result[$item['email']][] = $item['value'];
}

An example of this is here.

answered Jun 09 '15 at 13:08

Phylogenesis

7,775
19
27

Aha! I knew a more intelligent answer existed. I like it, but apparently the docs discourage it. – karns Jun 09 '15 at 13:10
2

@karns ... you had to work hard to finally get to this answer - enjoy! And thanx again everyone for the entertainment ;-) – Carsten Massmann Jun 09 '15 at 13:13
1

I think the docs are discouraging its use in fairly specific circumstances (where you don't necessarily know the underlying type of the array you're amending). In this case the entire array is constructed inside the loop, so I don't think that applies. – Phylogenesis Jun 09 '15 at 13:15
@cars10 - Anything to learn the language better ;) You're welcome. I think it was a result of my ignorance :D.. – karns Jun 09 '15 at 13:15
@Phylogenesis: I just noticed that your example host ideone.com seems to be blocked by our corporate firewall. Maybe I am not the only one? – Carsten Massmann Jun 09 '15 at 13:15
@cars10 That's certainly possible. – Phylogenesis Jun 09 '15 at 13:25
Good One @Phylogenesis Cleaner Way to achieve +1 – Narendrasingh Sisodia Jun 09 '15 at 13:30

score 1 · Answer 2 · answered Jun 09 '15 at 12:48

You can simply use foreach as

$myArray = 
[
  ['email' => 'email1@email.com', 'value' => '123'],
  ['email' => 'email1@email.com', 'value' => '456'],
  ['email' => 'email1@email.com', 'value' => '789'],
  ['email' => 'email2@email2.com', 'value' => '123'],
  ['email' => 'email2@email2.com', 'value' => '456'],
];
$result = array();
foreach ($myArray as $key => &$value) {
  if(isset($result[$value['email']])){
      array_push($result[$value['email']],$value['value']);
  }else{
      $result[$value['email']] = array($value['value']);
  }
}

DEMO

Group Values of Array According to Similar Keys - PHP

2 Answers2