Generate combination array PHP [duplicate] - php

Question

This question already has answers here:
PHP array combinations
(8 answers)
Closed 7 years ago.
Hi Guys i have an array like this
$array1 = array('a','b','c','d)
and i want to combine with output like this
'a,b,c'
'a,b,d'
'a,c,d'
'b,c,d'
The problem is to create a function with a variable number and not multiple variable, can anybody help me?

Answer 1

Make a try
[akshay#localhost tmp]$ cat permutation_comb.php
<?php
function _perm($comb,$arr)
{
$arr_len = count($arr);
$comb = intval($comb);
if ($comb > $arr_len)
{
$p = 0;
}
elseif ($arr_len == $comb)
{
$p = 1;
}
else {
if ($comb >= $arr_len - $comb)
{
$l = $comb+1;
for ($i = $l+1 ; $i <= $arr_len ; $i++)
$l *= $i;
$m = 1;
for ($i = 2 ; $i <= $arr_len-$comb ; $i++)
$m *= $i;
}
else {
$l = ($arr_len-$comb) + 1;
for ($i = $l+1 ; $i <= $arr_len ; $i++)
$l *= $i;
$m = 1;
for ($i = 2 ; $i <= $comb ; $i++)
$m *= $i;
}
}
if(!isset($p)){ $p = $l/$m ; }
$out = array_fill(0, $p, array_fill(0, $comb, '') );
$t = array();
for ($i = 0 ; $i < $comb ; $i++)
$t[$i] = $i;
$out[0] = $t;
for ($i = 1 ; $i < $p ; $i++)
{
if ($t[$comb-1] != count($arr)-1)
{
$t[$comb-1]++;
}
else {
$xx = -1;
for ($j = $comb-2 ; $j >= 0 ; $j--)
if ($t[$j]+1 != $t[$j+1])
{
$xx = $j;
break;
}
if ($xx == -1)
break;
$t[$xx]++;
for ($j = $xx+1 ; $j < $comb ; $j++)
$t[$j] = $t[$xx]+$j-$xx;
}
$out[$i] = $t;
}
for ($i = 0 ; $i < $p ; $i++)
for ($j = 0 ; $j < $comb ; $j++)
$out[$i][$j] = $arr[$out[$i][$j]];
return $out;
}
$Input = array('a','b','c','d');
$output = array_map(function($a){ return implode(",",$a); },_perm(3, $Input));
// Input
print_r($Input);
// Combination output
print_r($output);
?>
Output
[akshay#localhost tmp]$ php permutation_comb.php
Array
(
[0] => a
[1] => b
[2] => c
[3] => d
)
Array
(
[0] => a,b,c
[1] => a,b,d
[2] => a,c,d
[3] => b,c,d
)
To get all possible combination of chars modify calling part of function like below
$output = array();
for($i=1; $i<=count($Input); $i++)
{
$output = array_merge($output, array_map(function($a){ return implode(",",$a); },_perm($i, $Input)) ) ;
}
Which results
[akshay#localhost tmp]$ php permutation_comb.php
Array
(
[0] => a
[1] => b
[2] => c
[3] => d
)
Array
(
[0] => a
[1] => b
[2] => c
[3] => d
[4] => a,b
[5] => a,c
[6] => a,d
[7] => b,c
[8] => b,d
[9] => c,d
[10] => a,b,c
[11] => a,b,d
[12] => a,c,d
[13] => b,c,d
[14] => a,b,c,d
)