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phparraysfindunique

How to find values which were found before inside multi array

i do have currently following problem. I have to check if the array contains the exact same values and if they were found before.

int(3) wasn´t found before so it is 0, int(8) wasn´t found before so it is 0, int(5) wasn´t found before so it is 0, int(8) was found before so it is 1, int(3) and int(8) was not found together so it is 0, and so on.

I already tried it with array_unique but that didn´t work as i wanted

For example:

array(7) {
  [2] => array(1) {
    [0] => int(3)
  }
  [3] => array(1) {
    [0] => int(8)
  }
  [4] => array(1) {
    [0] => int(5)
  }
  [5] => array(1) {
    [0] => int(8)
  }
  [6] => array(2) {
    [0] => int(3)
    [1] => int(8)
  }
  [7] => array(2) {
    [0] => int(2)
    [1] => int(5)
  }
  [8] => array(2) {
    [0] => int(3)
    [1] => int(8)
  }
}

it must look something like this

array(7) {
  [2] => array(1) {
    [0] => int(0)
  }
  [3] => array(1) {
    [0] => int(0)
  }
  [4] => array(1) {
    [0] => int(0)
  }
  [5] => array(1) {
    [0] => int(1)
  }
  [6] => array(1) {
    [0] => int(0)
  }
  [7] => array(1) {
    [0] => int(0)
  }
  [8] => array(1) {
    [0] => int(1)
  }
}
Solution

  • You could use array_map() and serialize():

    <?php

$data = [
    2 => [
        3,
    ],
    3 => [
        8,
    ],
    4 => [
        5,
    ],
    5 => [
        8,
    ],
    6 => [
        3,
        8,
    ],
    7 => [
        2,
        5,
    ],
    8 => [
        3,
        8,
    ],
];

$occurrences = [];

$mapped = array_map(function (array $values) use (&$occurrences) {
    // create serialized representation of the values
    // which we can use as an index 
    $index = serialize($values);

    // haven't seen these values before
    if (!array_key_exists($index, $occurrences)) {
        $occurrences[$index] = 1;

        return 0;
    }

    // increase our counter
    $occurrences[$index]++;

    return $occurrences[$index] - 1;
}, $data);

var_dump($mapped);

    For reference, see:

    For an example, see: