Cartesian Product of N arrays - php

Question

I have a PHP array which looks like this example:
$array[0][0] = 'apples';
$array[0][1] = 'pears';
$array[0][2] = 'oranges';
$array[1][0] = 'steve';
$array[1][1] = 'bob';
And I would like to be able to produce from this a table with every possible combination of these, but without repeating any combinations (regardless of their position), so for example this would output
Array 0 Array 1
apples steve
apples bob
pears steve
pears bob
But I would like for this to be able to work with as many different arrays as possible.

Answer 1

this is called "cartesian product", php man page on arrays http://php.net/manual/en/ref.array.php shows some implementations (in comments).
and here's yet another one:
function array_cartesian() {
$_ = func_get_args();
if(count($_) == 0)
return array(array());
$a = array_shift($_);
$c = call_user_func_array(__FUNCTION__, $_);
$r = array();
foreach($a as $v)
foreach($c as $p)
$r[] = array_merge(array($v), $p);
return $r;
}
$cross = array_cartesian(
array('apples', 'pears', 'oranges'),
array('steve', 'bob')
);
print_r($cross);

Answer 2

You are looking for the cartesian product of the arrays, and there's an example on the php arrays site: http://php.net/manual/en/ref.array.php

Answer 3

Syom copied http://www.php.net/manual/en/ref.array.php#54979 but I adapted it this to become an associative version:
function array_cartesian($arrays) {
$result = array();
$keys = array_keys($arrays);
$reverse_keys = array_reverse($keys);
$size = intval(count($arrays) > 0);
foreach ($arrays as $array) {
$size *= count($array);
}
for ($i = 0; $i < $size; $i ++) {
$result[$i] = array();
foreach ($keys as $j) {
$result[$i][$j] = current($arrays[$j]);
}
foreach ($reverse_keys as $j) {
if (next($arrays[$j])) {
break;
}
elseif (isset ($arrays[$j])) {
reset($arrays[$j]);
}
}
}
return $result;
}

Answer 4

I needed to do the same and I tried the previous solutions posted here but could not make them work. I got a sample from this clever guy http://www.php.net/manual/en/ref.array.php#54979. However, his sample did not managed the concept of no repeating combinations. So I included that part. Here is my modified version, hope it helps:
$data = array(
array('apples', 'pears', 'oranges'),
array('steve', 'bob')
);
$res_matrix = $this->array_cartesian_product( $data );
foreach ( $res_matrix as $res_array )
{
foreach ( $res_array as $res )
{
echo $res . " - ";
}
echo "<br/>";
}
function array_cartesian_product( $arrays )
{
$result = array();
$arrays = array_values( $arrays );
$sizeIn = sizeof( $arrays );
$size = $sizeIn > 0 ? 1 : 0;
foreach ($arrays as $array)
$size = $size * sizeof( $array );
$res_index = 0;
for ( $i = 0; $i < $size; $i++ )
{
$is_duplicate = false;
$curr_values = array();
for ( $j = 0; $j < $sizeIn; $j++ )
{
$curr = current( $arrays[$j] );
if ( !in_array( $curr, $curr_values ) )
{
array_push( $curr_values , $curr );
}
else
{
$is_duplicate = true;
break;
}
}
if ( !$is_duplicate )
{
$result[ $res_index ] = $curr_values;
$res_index++;
}
for ( $j = ( $sizeIn -1 ); $j >= 0; $j-- )
{
$next = next( $arrays[ $j ] );
if ( $next )
{
break;
}
elseif ( isset ( $arrays[ $j ] ) )
{
reset( $arrays[ $j ] );
}
}
}
return $result;
}
The result would be something like this:
apples - steve
apples - bob
pears - steve
pears - bob
oranges - steve
oranges - bob
If you the data array is something like this:
$data = array(
array('Amazing', 'Wonderful'),
array('benefit', 'offer', 'reward'),
array('Amazing', 'Wonderful')
);
Then it will print something like this:
Amazing - benefit - Wonderful
Amazing - offer - Wonderful
Amazing - reward - Wonderful
Wonderful - benefit - Amazing
Wonderful - offer - Amazing
Wonderful - reward - Amazing

Answer 5

foreach($parentArray as $value) {
foreach($subArray as $value2) {
$comboArray[] = array($value, $value2);
}
}
Don't judge me..

Answer 6

This works I think - although after writing it I realised it's pretty similar to what others have put, but it does give you an array in the format requested. Sorry for the poor variable naming.
$output = array();
combinations($array, $output);
print_r($output);
function combinations ($array, & $output, $index = 0, $p = array()) {
foreach ( $array[$index] as $i => $name ) {
$copy = $p;
$copy[] = $name;
$subIndex = $index + 1;
if (isset( $array[$subIndex])) {
combinations ($array, $output, $subIndex, $copy);
} else {
foreach ($copy as $index => $name) {
if ( !isset($output[$index])) {
$output[$index] = array();
}
$output[$index][] = $name;
}
}
}
}

Answer 7

#user187291
I modified this to be
function array_cartesian() {
$_ = func_get_args();
if (count($_) == 0)
return array();
$a = array_shift($_);
if (count($_) == 0)
$c = array(array());
else
$c = call_user_func_array(__FUNCTION__, $_);
$r = array();
foreach($a as $v)
foreach($c as $p)
$r[] = array_merge(array($v), $p);
return $r;
}
so it returns that all-important empty array (the same result as no combinations) when you pass 0 arguments.
Only noticed this because I'm using it like
$combos = call_user_func_array('array_cartesian', $array_of_arrays);

Answer 8

function array_comb($arrays)
{
$result = array();
$arrays = array_values($arrays);
$sizeIn = sizeof($arrays);
$size = $sizeIn > 0 ? 1 : 0;
foreach ($arrays as $array)
$size = $size * sizeof($array);
for ($i = 0; $i < $size; $i ++)
{
$result[$i] = array();
for ($j = 0; $j < $sizeIn; $j ++)
array_push($result[$i], current($arrays[$j]));
for ($j = ($sizeIn -1); $j >= 0; $j --)
{
if (next($arrays[$j]))
break;
elseif (isset ($arrays[$j]))
reset($arrays[$j]);
}
}
return $result;
}

Answer 9

I had to make combinations from product options. This solution uses recursion and works with 2D array:
function options_combinations($options) {
$result = array();
if (count($options) <= 1) {
$option = array_shift($options);
foreach ($option as $value) {
$result[] = array($value);
}
} else {
$option = array_shift($options);
$next_option = options_combinations($options);
foreach ($next_option as $next_value) {
foreach ($option as $value) {
$result[] = array_merge($next_value, array($value));
}
}
}
return $result;
}
$options = [[1,2],[3,4,5],[6,7,8,9]];
$c = options_combinations($options);
foreach ($c as $combination) {
echo implode(' ', $combination)."\n";
}

Answer 10

Elegant implementation based on native Python function itertools.product
function direct_product(array ...$arrays)
{
$result = [[]];
foreach ($arrays as $array) {
$tmp = [];
foreach ($result as $x) {
foreach ($array as $y) {
$tmp[] = array_merge($x, [$y]);
}
}
$result = $tmp;
}
return $result;
}