How to modify the classic Cartesian Product Code

How can I modify the classic Cartesian product code? Cartesian product code: & lt ;? PHPfunctionDescartes () {& nbsp; $ t = func_get_args (); & nbsp; if (func_num_args () = classic Cartesian product code, how can I modify it?
Cartesian product code:


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 = 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;
}

$ Arr = array (
Array ('A1', 'A2 '),
'B ',
Array ('C1 ', 'C2 '),
Array ('d1 ', 'D2', 'd3 '),
Array ('e1 ', 'E2', 'E3 ')
// ...... Omitting other elements (or arrays ),
);

$ R = Descartes ($ arr );
Print_r ($ r );
?>

//////////////////////////////////////

Output:

Array
(
[0] => Array
(
[0] => a1
[1] => B
[2] => c1
[3] => d1
[4] => e1
)
[1] => Array
(
[0] => a1
[1] => B
[2] => c1
[3] => d1
[4] => e2
)
......
)


////////////////////
Now I only want three elements. The first element must have a1 or a2. How can I change the code?
Array
(
[0] => Array
(
[0] => a1
[1] => B
[2] => c1
)
......
[1] => Array
(
[0] => a2
[1] => c2
[2] => d3
)
......
)



------ Solution --------------------
For
$ Arr = array (
Array ('A1', 'A2 '),
'B ',
Array ('C1 ', 'C2 '),
Array ('d1 ', 'D2', 'd3 '),
Array ('e1 ', 'E2', 'E3 ')
// ...... Omitting other elements (or arrays ),
);
You must first
$ Arr = array (
'B ',
Array ('C1 ', 'C2 '),
Array ('d1 ', 'D2', 'd3 '),
Array ('e1 ', 'E2', 'E3 ')
// ...... Omitting other elements (or arrays ),
);
Evaluate the combination of M and 2
$ C = combination ($ arr, 2 );
Then the Cartesian product is obtained for the result of the combination.

$ R = array ();
Foreach ($ c as $ v)
$ R = array_merge ($ r, Descartes (array ('A1', 'A2 '), $ v [0], $ v [1]);
Print_r ($ r );

PHP code

Array(    [0] => Array        (            [0] => a1            [1] => d1            [2] => e1        )    [1] => Array        (            [0] => a1            [1] => d1            [2] => e2        )    [2] => Array        (            [0] => a1            [1] => d1            [2] => e3        )    [3] => Array        (            [0] => a1            [1] => d2            [2] => e1        )    [4] => Array        (            [0] => a1            [1] => d2            [2] => e2        )    [5] => Array        (            [0] => a1            [1] => d2            [2] => e3        )    [6] => Array        (            [0] => a1            [1] => d3            [2] => e1        )    [7] => Array        (            [0] => a1            [1] => d3            [2] => e2        )    [8] => Array        (            [0] => a1            [1] => d3            [2] => e3        )    [9] => Array        (            [0] => a2            [1] => d1            [2] => e1        )    [10] => Array        (            [0] => a2            [1] => d1            [2] => e2        )    [11] => Array        (            [0] => a2            [1] => d1            [2] => e3        )    [12] => Array        (            [0] => a2            [1] => d2            [2] => e1        )    [13] => Array        (            [0] => a2            [1] => d2            [2] => e2        )    [14] => Array        (            [0] => a2            [1] => d2            [2] => e3        )    [15] => Array        (            [0] => a2            [1] => d3            [2] => e1        )    [16] => Array        (            [0] => a2            [1] => d3            [2] => e2        )    [17] => Array        (            [0] => a2            [1] => d3            [2] => e3        )    [18] => Array        (            [0] => a1            [1] => c1            [2] => e1        )    [19] => Array        (            [0] => a1            [1] => c1            [2] => e2        )    [20] => Array        (            [0] => a1            [1] => c1            [2] => e3        )    [21] => Array        (            [0] => a1            [1] => c2            [2] => e1        )    [22] => Array        (            [0] => a1            [1] => c2            [2] => e2        )    [23] => Array        (            [0] => a1            [1] => c2            [2] => e3        )    [24] => Array        (            [0] => a2            [1] => c1            [2] => e1        )    [25] => Array        (            [0] => a2            [1] => c1            [2] => e2        )    [26] => Array        (            [0] => a2            [1] => c1            [2] => e3        )    [27] => Array        (            [0] => a2            [1] => c2            [2] => e1        )    [28] => Array        (            [0] => a2            [1] => c2            [2] => e2        )    [29] => Array        (            [0] => a2            [1] => c2            [2] => e3        )    [30] => Array        (            [0] => a1            [1] => c1            [2] => d1        )    [31] => Array        (            [0] => a1            [1] => c1            [2] => d2        )    [32] => Array        (            [0] => a1            [1] => c1            [2] => d3        )    [33] => Array        (            [0] => a1            [1] => c2            [2] => d1        )    [34] => Array        (            [0] => a1            [1] => c2            [2] => d2        )    [35] => Array        (            [0] => a1            [1] => c2            [2] => d3        )    [36] => Array        (            [0] => a2            [1] => c1            [2] => d1        )    [37] => Array        (            [0] => a2            [1] => c1            [2] => d2        )    [38] => Array        (            [0] => a2            [1] => c1            [2] => d3        )    [39] => Array        (            [0] => a2            [1] => c2            [2] => d1        )    [40] => Array        (            [0] => a2            [1] => c2            [2] => d2        )    [41] => Array        (            [0] => a2            [1] => c2            [2] => d3        )    [42] => Array        (            [0] => a1            [1] => b            [2] => e1        )    [43] => Array        (            [0] => a1            [1] => b            [2] => e2        )    [44] => Array        (            [0] => a1            [1] => b            [2] => e3        )    [45] => Array        (            [0] => a2            [1] => b            [2] => e1        )    [46] => Array        (            [0] => a2            [1] => b            [2] => e2        )    [47] => Array        (            [0] => a2            [1] => b            [2] => e3        )    [48] => Array        (            [0] => a1            [1] => b            [2] => d1        )    [49] => Array        (            [0] => a1            [1] => b            [2] => d2        )    [50] => Array        (            [0] => a1            [1] => b            [2] => d3        )    [51] => Array        (            [0] => a2            [1] => b            [2] => d1        )    [52] => Array        (            [0] => a2            [1] => b            [2] => d2        )    [53] => Array        (            [0] => a2            [1] => b            [2] => d3        )    [54] => Array        (            [0] => a1            [1] => b            [2] => c1        )    [55] => Array        (            [0] => a1            [1] => b            [2] => c2        )    [56] => Array        (            [0] => a2            [1] => b            [2] => c1        )    [57] => Array        (            [0] => a2            [1] => b            [2] => c2        ))