求笛卡尔积的php代码

来源：互联网发布：淘宝达人2017还赚钱吗编辑：程序博客网时间：2024/05/19 13:14

笛卡尔（Descartes）乘积又叫直积。设A、B是任意两个集合，在集合A中任意取一个元素x，在集合B中任意取一个元素y，组成一个有序对（x，y），把这样的有序对作为新的元素，他们的全体组成的集合称为集合A和集合B的直积，记为A×B，即A×B={（x，y）|x∈A且y∈B}。

function Descartes() {  $t = func_get_args();  if(func_num_args() == 1) return call_user_func_array( __FUNCTION__, $t[0] );   $a = array_shift($t);  if(! is_array($a)) $a = array($a);  $a = array_chunk($a, 1);  do {$r = array();$b = array_shift($t);if(! is_array($b)) $b = array($b);foreach($a as $p)foreach(array_chunk($b, 1) as $q)$r[] = array_merge($p, $q);$a = $r;  }while($t);  return $r;}

示例

$arr = array(  array(a1,a2,),  b,  array(c1,c2,),  array(d1,d2,d3),  //......省略其它元素（也可以是数组），); $r = Descartes( $arr );

结果

Array(    [0] => Array        (            [0] => a1            [1] => b            [2] => c1            [3] => d1        )    [1] => Array        (            [0] => a1            [1] => b            [2] => c1            [3] => d2        )    [2] => Array        (            [0] => a1            [1] => b            [2] => c1            [3] => d3        )    [3] => Array        (            [0] => a1            [1] => b            [2] => c2            [3] => d1        )    [4] => Array        (            [0] => a1            [1] => b            [2] => c2            [3] => d2        )    [5] => Array        (            [0] => a1            [1] => b            [2] => c2            [3] => d3        )    [6] => Array        (            [0] => a2            [1] => b            [2] => c1            [3] => d1        )    [7] => Array        (            [0] => a2            [1] => b            [2] => c1            [3] => d2        )    [8] => Array        (            [0] => a2            [1] => b            [2] => c1            [3] => d3        )    [9] => Array        (            [0] => a2            [1] => b            [2] => c2            [3] => d1        )    [10] => Array        (            [0] => a2            [1] => b            [2] => c2            [3] => d2        )    [11] => Array        (            [0] => a2            [1] => b            [2] => c2            [3] => d3        ))