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<?php function reindexArray($array, $column) { return array_combine( array_map(function($x) use ($column) { return $x[$column]; }, $array), $array ); } function arrayJoin($array1, $array2, $column, $default=null) { //in PHP 5.5 it's just array_column() call: $array1 = reindexArray($array1, $column); $array2 = reindexArray($array2, $column); $blank1 = array_combine( array_keys(current($array1)), array_fill(1, count(current($array1)), $default) ); $blank2 = array_combine( array_keys(current($array2)), array_fill(1, count(current($array2)), $default) ); unset($blank1[$column], $blank2[$column]); return array_merge( array_map(function($x) use ($array1, $blank2) { return array_merge($array1[$x], $blank2); }, array_keys(array_diff_key($array1, $array2))), array_map(function($x) use ($array1, $array2) { return array_merge($array1[$x], $array2[$x]); }, array_keys(array_intersect_key($array1, $array2))), array_map(function($x) use ($array2, $blank1) { return array_merge($array2[$x], $blank1); }, array_keys(array_diff_key($array2, $array1))) ); } $array1 = array(); $array1[]=array('subscribers'=>2,'dt_date'=>'2014-02-27'); $array1[]=array('subscribers'=>2,'dt_date'=>'2014-02-25'); $array1[]=array('subscribers'=>1,'dt_date'=>'2014-02-07'); $array2 = array(); $array2[]=array('unsubscribers'=>1,'dt_date'=>'2014-02-27'); $array2[]=array('unsubscribers'=>1,'dt_date'=>'2014-02-01'); var_dump(arrayJoin($array1, $array2, 'dt_date', 0));