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Permutation of values ​​in an array

Assume an array

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
    [3] => 4
)

I want to call a function by providing two parameters (both arrays) with the following permutations -

array(1) and array(2,3,4)
array(1,2) and array(3,4)
array(1,2,3) and array (4)
array(1,3) and array(2,4)
array(1,4) and array(2,3)
array(2) and array(1,3,4)
and so on...

Of course, the actual arrays will be larger.

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3 answers

I don’t know what this "permutation" is called (it may not be a permutation), but it was promising for me to use the fact that the elements in the set are ordered (if not, then the order is index, so use the index instead of the value), so to go from right to left and combining all the left with the right combinations.

This is possible with recursion or with the stack, I usually prefer the stack.

Usage as suggested (function call encapsulation):

$funky = function($a, $b) {
    printf("(%s) and (%s)\n", implode(',', $a), implode(',', $b));
};

$paired = function($function) {
    return function(array $array) use ($function) {
        ...
    };
};


$funkyAll = $paired($funky);
$funkyAll(range(1, 5));

( ) ( ):

(1) and (2,3,4,5)    (2,4) and (1,3,5)    (1,4,5) and (2,3)
(2) and (1,3,4,5)    (2,5) and (1,3,4)    (2,3,4) and (1,5)
(3) and (1,2,4,5)    (3,4) and (1,2,5)    (2,3,5) and (1,4)
(4) and (1,2,3,5)    (3,5) and (1,2,4)    (2,4,5) and (1,3)
(5) and (1,2,3,4)    (4,5) and (1,2,3)    (3,4,5) and (1,2)
(1,2) and (3,4,5)    (1,2,3) and (4,5)    (1,2,3,4) and (5)
(1,3) and (2,4,5)    (1,2,4) and (3,5)    (1,2,3,5) and (4)
(1,4) and (2,3,5)    (1,2,5) and (3,4)    (1,2,4,5) and (3)
(1,5) and (2,3,4)    (1,3,4) and (2,5)    (1,3,4,5) and (2)
(2,3) and (1,4,5)    (1,3,5) and (2,4)    (2,3,4,5) and (1)

( gist) (array_pop array_shift):

(1) and (2,3,4,5)    (2,4) and (1,3,5)    (1,4,5) and (2,3)
(2) and (1,3,4,5)    (2,5) and (1,3,4)    (1,3,4) and (2,5)
(3) and (1,2,4,5)    (2,4,5) and (1,3)    (1,3,5) and (2,4)
(4) and (1,2,3,5)    (2,3,4) and (1,5)    (1,3,4,5) and (2)
(5) and (1,2,3,4)    (2,3,5) and (1,4)    (1,2,3) and (4,5)
(4,5) and (1,2,3)    (2,3,4,5) and (1)    (1,2,4) and (3,5)
(3,4) and (1,2,5)    (1,2) and (3,4,5)    (1,2,5) and (3,4)
(3,5) and (1,2,4)    (1,3) and (2,4,5)    (1,2,4,5) and (3)
(3,4,5) and (1,2)    (1,4) and (2,3,5)    (1,2,3,4) and (5)
(2,3) and (1,4,5)    (1,5) and (2,3,4)    (1,2,3,5) and (4)

:

$stack[] = array(array(), $array);
while (list($left, $right) = array_pop($stack)) {
    $min = end($left);
    foreach ($right as $value)
    {
        if ($value < $min) continue;
        $left2 = array_merge($left, array($value));
        $right2 = array_diff($right, $left2);
        if (!($left2 && $count = count($right2))) continue;
        $function($left2, $right2);
        --$count && $stack[] = array($left2, $right2);
    }
}

, .

, : ( , )

+2

array_pop array_merge

chk this url

http://php.net/manual/en/function.array-pop.php

sarafov URL

http://www.sonyjose.in/blog/?p=62

-

foreach($combinations as $combination)
    while(in_array($combination)){
        $arr = array_pop($combination);
        foo($fruit , $combination); 
    }
}
+1

I think this is what you need.

The code:

<?php

function combinations($arr, $n)
{
    $res = array();

    foreach ($arr[$n] as $item)
    {
        if ($n==count($arr)-1)
            $res[]=$item;
        else
        {
            $combs = combinations($arr,$n+1);

            foreach ($combs as $comb)
            {
                $res[] = "$item $comb";
            }
        }
    }
    return $res;
}

// Your ARRAY
//
// you can put as many items in each subarray as you like... 
// and as many subarrays as you like
$words = array(array('A','B'),array('C','D'), array('E','F'));

$combos = combinations($words,0);  // ALWAYS, call it with 0 as the last parameter
print_r($combos);

?>

Output:

Array
(
    [0] => A C E
    [1] => A C F
    [2] => A D E
    [3] => A D F
    [4] => B C E
    [5] => B C F
    [6] => B D E
    [7] => B D F
)

Usage: (as in your example)

$combos = combinations(array(array(1,4),array(2,3)));
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