How to check duplicates in array of objects by first key?

Question

I have an array of objects

[new BalanceSheet('2018', '356743', '-56913', '189632', '122733'),
 new BalanceSheet('2018', '4562343', '236913', '198732', '6552733'),
 new BalanceSheet('2017', '2234643', '55913', '19435342', '855342733')
]

And i need to throw an exception when the first key in object are duplicate another -> 2018 === 2018

I understand how i can to get the key

  class BalanceSheet  {
   public function __construct(string $year, ...) {
        $this->year = $year;    
        ...
    }
  public function getYear() {
        return $this->year;
    }

private function isDuplicateData($sheets) {
        foreach ($sheets as $key => $sheet) {
            echo $key . ' year = ' . $sheet->getYear();
        }
    }

but i don't understand what the easiest way to compare keys in isDuplicateData

If your array is sorted, you could perform a binary search. Depends on your use case. — Rocky
– Rocky, Commented May 12, 2020 at 5:04

Adam Winter · Accepted Answer · 2020-05-12 05:47:19Z

1

If all you need to do is throw an exception, then maybe create an array of the keys and apply array_unique().

    private function isDuplicateData($sheets) {
        $keys = [];
        foreach ($sheets as $key => $sheet) {
             $keys[]=$key;
        }
        if (count($keys) != count(array_unique($keys)){
            //throw exception
        }
    }

answered May 12, 2020 at 5:47

Adam Winter

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Comments

Farista Latuconsina · Accepted Answer · 2020-05-12 05:51:34Z

1

How about using php array_filter:

$objects = array(
    new BalanceSheet('2018', '356743', '-56913', '189632', '122733'),
    new BalanceSheet('2018', '4562343', '236913', '198732', '6552733'),
    new BalanceSheet('2017', '2234643', '55913', '19435342', '855342733'),
);
$known = array();
$filtered = array_filter($objects, function ($val) use (&$known) {
    // In your case the key would be years
    $unique = !in_array($val->years, $known);
    $known[] = $val->years;
    return $unique;
});

answered May 12, 2020 at 5:51

Farista Latuconsina

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Comments

user13518620 · Accepted Answer · 2020-05-12 05:25:12Z

0

You can compare length of array and length of array_diff.

count($arrayA) == count(array_diff($arrayA,$arrayB));

answered May 12, 2020 at 5:25

user13518620

Comments

Ali Ali · Accepted Answer · 2020-05-12 05:45:00Z

If you want to delete duplicates you can use the PHP function array_unique, this will check for the duplicates and delete them:

array_unique ( $sheets );

If you want to throw an exception only, you can extract and add the years to another array then check if there are any duplicates:

private function isDuplicateData($sheets) {
$isdublicate = array();
foreach ($sheets as $key => $sheet) {
            echo $key . ' year = ' . $sheet->getYear();

$isdublicate[] = $sheet->getYear();
}
for ($i = 0; $i <  count($isdublicate); $i++) 
    { 
        if ($isdublicate[abs($isdublicate[$i])] >= 0) 
            $isdublicate[abs($isdublicate[$i])] = -$isdublicate[abs($isdublicate[$i])]; 
        else
            //Here throw the exception 
    } 
}

The above for loop logic is here.

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