Get occurences of an object in an object array PHP

Solution:

You don't need to use any elaborate serialization or encoding to create composite keys for grouping. Just implode each row's values (assuming they all contain the same columns in the same order) to create an identifying key for the result array.

On the first encounter, store the row's data in the group and set the group's count to 1; on any subsequent encounter, increment the group's counter.

Code: (Demo)

$result = [];
foreach ($array as $row) {
    $compositeKey = implode('_', $row);
    if (!isset($result[$compositeKey])) {
        $result[$compositeKey] = $row + ['count' => 1];
    } else {
        ++$result[$compositeKey]['count'];
    }
}
var_export(array_values($result));
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Output:

array (
  0 => 
  array (
    'manufacturer' => 'KInd',
    'brand' => 'ABC',
    'used' => 'true',
    'count' => 2,
  ),
  1 => 
  array (
    'manufacturer' => 'KInd',
    'brand' => 'ABC',
    'used' => 'false',
    'count' => 1,
  ),
)
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Other posts that leverage multiple identifying column values for grouping:

• Group/Merge rows from two 2d arrays based on 3 identifying columns and fill missing column values with null
• Group rows of data, sum number of occurrences in each group, and print data as formatted strings
• Group data in a multidimensional array based on two columns
• Group rows of a multidimensional array and form comma-separated values within each group
• Group rows by two columns, filter grouped data to only keep the lowest value, and restructure associative rows
• Group rows of data, maintain a subarray of ids within the group, and only present the lowest id in each group as the first level key
• Group multidimensional array data based on two column values and sum values of one column in each group
• how to create a pivot array in php

Solution:

If I understand you correctly, this should help

function getUniqWithCounts(array $data): array
{
    $result = [];
    foreach ($data as $item) {
        $hash = md5(serialize($item));

        if (isset($result[$hash])) {
            $result[$hash]['count']++;
            continue;
        }
        $item['count'] = 1;
        $result[$hash] = $item;
    }

    return array_values($result);
}
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