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<?php $array = [ ['city' => 'NewYork', 'cash' => '1000'], ['city' => 'Philadelphia', 'cash' => '2300'], ['city' => 'NewYork', 'cash' => '2000'] ]; $result = []; foreach ($array as $a) { if (!isset($result[$a['city']])) { $result[$a['city']] = $a; // store temporary city-keyed result array (avoid Notices) } else { $result[$a['city']]['cash'] += $a['cash']; // add current value to previous value } } var_export(array_values($result)); // remove temporary keys

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