PHP De-duplicate a multidimensional array

Question

Firstly, I realise this may appear as a duplicate as I have read a number of questions on a similar topic (1, 2) but I'm struggling to see how to re-architect the code base to fit my senario.

I am attempting to take an existing multi-dimensional array and remove any nodes that have a duplicate in a specific field. Here is dataset I am working with:

array(3) {
  [0]=>
  array(3) {
    ["company"]=>
    string(9) "Company A"
    ["region"]=>
    string(4) "EMEA"
    ["ctype"]=>
    string(8) "Customer"
  }
  [1]=>
  array(3) {
    ["company"]=>
    string(9) "Company A"
    ["region"]=>
    string(4) "EMEA"
    ["ctype"]=>
    string(8) "Customer"
  }
  [2]=>
  array(3) {
    ["company"]=>
    string(9) "Company C"
    ["region"]=>
    string(4) "EMEA"
    ["ctype"]=>
    string(8) "Customer"
  }
}

If this wasn't a multi-dimensional array would use in_array() to see if the dataset['company'] existed. If not I'd add it to my $unique array, something like this:

$unique = array();

foreach ($dataset as $company) {
  $company_name = $company['company'];

  if ( !in_array($company_name, $unique) ) {
    array_push($unique, $company_name);
  }
}
var_dump($unique);

But I'm unsure how to traverse the muti-dimensional array to get to the ['company'] data to see if it exists (as it is the only item I need to check to see if it already exists).

I am looking to output exactly the same data as the initial dataset, just with the duplicate removed. Please can you point me in the right direction?

u_mulder · Accepted Answer · 2015-01-13 12:10:57Z

1

Store already checked companies in some side-array:

$unique = array();
$companies = array();

foreach ($dataset as $company) {
    $company_name = $company['company'];

    if ( !in_array($company_name, $companies) ) {
        array_push($unique, $company);
        array_push($companies, $company_name);
    }
}

var_dump($unique);

answered Jan 13, 2015 at 12:10

u_mulder

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1 Comment

Sheixt Over a year ago

This seems to work! Will come back and confirm after further testing. Thanks!

markcial · Accepted Answer · 2015-01-13 12:11:26Z

1

Use array_filter with the use keyword and a pass by reference array.

>>> $data
=> [
       [
           "company" => "Company A",
           "region"  => "EMEA",
           "ctype"   => "Customer"
       ],
       [
           "company" => "Company A",
           "region"  => "EMEA",
           "ctype"   => "Customer"
       ],
       [
           "company" => "Company C",
           "region"  => "EMEA",
           "ctype"   => "Customer"
       ]
   ]
$whitelist = [];

array_filter($data, function ($item) use (&$whitelist) { 
  if (!in_array($item['company'], $whitelist)) { 
    $whitelist[] = $item['company']; 
    return true; 
  }; 
  return false; 
});

=> [
       0 => [
           "company" => "Company A",
           "region"  => "EMEA",
           "ctype"   => "Customer"
       ],
       2 => [
           "company" => "Company C",
           "region"  => "EMEA",
           "ctype"   => "Customer"
       ]
   ]

answered Jan 13, 2015 at 12:11

markcial

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3 Comments

Sheixt Over a year ago

Whilst I follow the concept of this, I'm not getting the right output. The returned data is: array(2) { [0]=> string(9) "Company A" [1]=> string(9) "Company C" }

Sheixt Over a year ago

Due to the PHP version running on the server I had to amend $whitelist = []; to $whitelist = array(); I assume this has no impact?

markcial Over a year ago

not at all, is just the same object but with different styles of declaration.

GNewton · Accepted Answer · 2015-01-13 12:13:56Z

0

What you seem to be describing is something PHP can already cater for. Have you heard of the array_unique function before? It doesn't work recursively, but while browsing through the PHP docs someone has already created a function which will work.

recursive array unique for multiarrays

function super_unique($array)
{
  $result = array_map("unserialize", array_unique(array_map("serialize", $array)));

  foreach ($result as $key => $value)
  {
    if ( is_array($value) )
    {
      $result[$key] = super_unique($value);
    }
  }

  return $result;
}

Let me know if this works, as I am currently out the office at the moment.

answered Jan 13, 2015 at 12:13

GNewton

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2 Comments

Sheixt Over a year ago

This isn't far away. It seems to de-dupe, however there is still an erroneous (empty) array at the end of the data: ` array(3) { ["company"]=> string(9) "Company A" ["region"]=> string(4) "EMEA" ["ctype"]=> string(8) "Customer" } array(3) { ["company"]=> string(9) "Company C" ["region"]=> string(4) "EMEA" ["ctype"]=> string(8) "Customer" } array(2) { [0]=> NULL [2]=> NULL }`

GNewton Over a year ago

It was a 'shot in the dark' sort of thing while i was browsing through on my laptop, as I wasn't at my normal development machine. I see in the comments above, you have found your answer. Happy coding!

Spoke44 · Accepted Answer · 2015-01-13 13:26:39Z

0

To rebuild an array without duplicates :

$result = array();
foreach($datas as $data){
  foreach($data as $key => $value){
    $result[$key][$value] = $value;
  }
}

print_r($result);

OUTPUT :

Array
(
    [company] => Array
        (
            [Company A] => Company A
            [Company C] => Company C
        )

    [region] => Array
        (
            [EMEA] => EMEA
        )

    [ctype] => Array
        (
            [Customer] => Customer
        )

)

Keeping the same architecture :

$datas = array(
  array(
    "company"=>"Company A",
    "region"=>"EMEA",
    "ctype"=>"Customer"
  ),
  array(
    "company"=>"Company A",
    "region"=>"EMEA",
    "ctype"=>"Customer"
  ),
  array(
    "company"=>"Company C",
    "region"=>"EMEA",
    "ctype"=>"Customer"
  )
);

function removeDuplicateOnField($datas, $field){
  $result = array();

  foreach($datas as $key => &$data){
      if(isset($data[$field]) AND !isset($result[$data[$field]])){
        $result[$data[$field]] = $data;
      }
      else 
        unset($datas[$key]);
  }
  return $datas;
}

$result = removeDuplicateOnField($datas, "company");

print_r($result);

edited Jan 13, 2015 at 13:26

answered Jan 13, 2015 at 12:12

Spoke44

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1 Comment

Sheixt Over a year ago

Ah, I'm looking to keep the same data structure for the output as was inserted (i.e. as the same as in the first code snippet in the question). This is because I will need to manipulate the data with the associations that exist.

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