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I have an array of 7 numbers (1,2,3,4,5,6,7) and I want to choose 5 of the numbers like
(1,2,3,4,5), (1,2,3,4,6), (1,2,3,4,7).
Note that (1,2,3,4,5) is equal to (4,5,3,1,2), so only one of those should be included in the output.
I would like to know if there is a function in PHP or any algorithm that can do this ?
I have no idea where to start from.
Can you help me ?
I want all the combinations of 7 given numbers ( they are taken from an array ) put into 5 slots, disregarding order.
You can use the solution found here http://stereofrog.com/blok/on/070910.
Incase the link goes down here's the code....
class Combinations implements Iterator
{
protected $c = null;
protected $s = null;
protected $n = 0;
protected $k = 0;
protected $pos = 0;
function __construct($s, $k) {
if(is_array($s)) {
$this->s = array_values($s);
$this->n = count($this->s);
} else {
$this->s = (string) $s;
$this->n = strlen($this->s);
}
$this->k = $k;
$this->rewind();
}
function key() {
return $this->pos;
}
function current() {
$r = array();
for($i = 0; $i < $this->k; $i++)
$r[] = $this->s[$this->c[$i]];
return is_array($this->s) ? $r : implode('', $r);
}
function next() {
if($this->_next())
$this->pos++;
else
$this->pos = -1;
}
function rewind() {
$this->c = range(0, $this->k);
$this->pos = 0;
}
function valid() {
return $this->pos >= 0;
}
protected function _next() {
$i = $this->k - 1;
while ($i >= 0 && $this->c[$i] == $this->n - $this->k + $i)
$i--;
if($i < 0)
return false;
$this->c[$i]++;
while($i++ < $this->k - 1)
$this->c[$i] = $this->c[$i - 1] + 1;
return true;
}
}
foreach(new Combinations("1234567", 5) as $substring)
echo $substring, ' ';
12345 12346 12347 12356 12357 12367 12456 12457 12467 12567 13456 13457 13467 13567 14567 23456 23457 23467 23567 24567 34567
<?php
echo "<pre>";
$test = array("test_1","test_2","test_3");
// Get Combination
$return = uniqueCombination($test);
//Sort
sort($return);
//Pretty Print
print_r(array_map(function($v){ return implode(",", $v); }, $return));
function uniqueCombination($in, $minLength = 1, $max = 2000) {
$count = count($in);
$members = pow(2, $count);
$return = array();
for($i = 0; $i < $members; $i ++) {
$b = sprintf("%0" . $count . "b", $i);
$out = array();
for($j = 0; $j < $count; $j ++) {
$b{$j} == '1' and $out[] = $in[$j];
}
count($out) >= $minLength && count($out) <= $max and $return[] = $out;
}
return $return;
}
?>
output
Array
(
[0] => test_1
[1] => test_2
[2] => test_3
[3] => test_1,test_2
[4] => test_1,test_3
[5] => test_2,test_3
[6] => test_1,test_2,test_3
)
The Math_Combinatorics in PEAR repository does exactly what you want:
A package that returns all the combinations and permutations, without
repetition, of a given set and subset size. Associative arrays are
preserved.
require_once 'Math/Combinatorics.php';
$combinatorics = new Math_Combinatorics;
$input = array(1, 2, 3, 4, 5, 6, 7);
$output = $combinatorics->combinations($input, 5); // 5 is the subset size
// 1,2,3,4,5
// 1,2,3,4,6
// 1,2,3,4,7
// 1,2,3,5,6
// 1,2,3,5,7
// 1,2,3,6,7
// 1,2,4,5,6
// 1,2,4,5,7
// 1,2,4,6,7
// 1,2,5,6,7
// 1,3,4,5,6
// 1,3,4,5,7
// 1,3,4,6,7
// 1,3,5,6,7
// 1,4,5,6,7
// 2,3,4,5,6
// 2,3,4,5,7
// 2,3,4,6,7
// 2,3,5,6,7
// 2,4,5,6,7
// 3,4,5,6,7
Another solution that bases on stack. It's quit fast but eats much memory.
Hope that helps someone.
In detail:
function _combine($numbers, $length)
{
$combinations = array();
$stack = array();
// every combinations can be ordered
sort($numbers);
// startup
array_push($stack, array(
'store' => array(),
'options' => $numbers,
));
while (true) {
// pop a item
$item = array_pop($stack);
// end of stack
if (!$item) {
break;
}
// valid store
if ($length <= count($item['store'])) {
$combinations[] = $item['store'];
continue;
}
// bypass when options are not enough
if (count($item['store']) + count($item['options']) < $length) {
continue;
}
foreach ($item['options'] as $index => $n) {
$newStore = $item['store'];
$newStore[] = $n;
// every combine can be ordered
// so accept only options which is greater than store numbers
$newOptions = array_slice($item['options'], $index + 1);
// push new items
array_push($stack, array(
'store' => $newStore,
'options' => $newOptions,
));
}
}
return $combinations;
}
Improved this answer to work with associative array as well:
function uniqueCombination($values, $minLength = 1, $maxLength = 2000) {
$count = count($values);
$size = pow(2, $count);
$keys = array_keys($values);
$return = [];
for($i = 0; $i < $size; $i ++) {
$b = sprintf("%0" . $count . "b", $i);
$out = [];
for($j = 0; $j < $count; $j ++) {
if ($b[$j] == '1') {
$out[$keys[$j]] = $values[$keys[$j]];
}
}
if (count($out) >= $minLength && count($out) <= $maxLength) {
$return[] = $out;
}
}
return $return;
}
Eg:
print_r(uniqueCombination([
'a' => 'xyz',
'b' => 'pqr',
]);
Result:
Array
(
[0] => Array
(
[b] => pqr
)
[1] => Array
(
[a] => xyz
)
[2] => Array
(
[a] => xyz
[b] => pqr
)
)
It will still work for non-associative arrays:
print_r(uniqueCombination(['a', 'b']);
Result:
Array
(
[0] => Array
(
[1] => b
)
[1] => Array
(
[0] => a
)
[2] => Array
(
[0] => a
[1] => b
)
)
New solution which optimizes speed and memory for combining algorithm
Mindset: generate combinations K numbers of Array of numbers. New solution will use K 'for' statements. One 'for' One number.
Such as: $K = 5 mean that 5 of 'for' statements is used
$total = count($array);
$i0 = -1;
for ($i1 = $i0 + 1; $i1 < $total; $i1++) {
for ($i2 = $i1 + 1; $i2 < $total; $i2++) {
for ($i3 = $i2 + 1; $i3 < $total; $i3++) {
for ($i4 = $i3 + 1; $i4 < $total; $i4++) {
for ($i5 = $i4 + 1; $i5 < $total; $i5++) {
$record = array();
for ($i = 1; $i <= $k; $i++) {
$t = "i$i";
$record[] = $array[$$t];
}
$callback($record);
}
}
}
}
}
And detail of code that generated the real code that will be execute by eval() function
function combine($array, $k, $callback)
{
$total = count($array);
$init = '
$i0 = -1;
';
$sample = '
for($i{current} = $i{previous} + 1; $i{current} < $total; $i{current}++ ) {
{body}
}
';
$do = '
$record = array();
for ($i = 1; $i <= $k; $i++) {
$t = "i$i";
$record[] = $array[$$t];
}
$callback($record);
';
$for = '';
for ($i = $k; $i >= 1; $i--) {
switch ($i) {
case $k:
$for = str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $do], $sample);
break;
case 1:
$for = $init . str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $for], $sample);
break;
default:
$for = str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $for], $sample);
break;
}
}
// execute
eval($for);
}
How to combine K numbers of Array
$k = 5;
$array = array(1, 2, 3, 4, 5, 6, 7);
$callback = function ($record) {
echo implode($record) . "\n";
};
combine($array, $k, $callback);
I found the other answers here confusing or overly complicated, so I wrote my own. I think this is a simple solution with a recursive method. The basic idea is that you go through your array and for each item decide whether or not it is in the combination (actually, you don't decide, you recursively try both ways). You make this choice for the first item and then combine it with the recursively generated combinations of the rest of the array. This solution fills a result array with every combination of your array as a sub-array. It uses the items in order and it preserves associations, including with numeric keys.
function combinations(array $items, int $numToChoose, array &$results, $comb = []): void {
if (count($items) < $numToChoose) {
throw new \Exception("Asked to choose $numToChoose items from an array of length ". count($items));
}
// if nothing left to choose, we have a complete combination
if ($numToChoose === 0) {
$results[] = $comb;
return;
}
// if we have to choose everything at this point, then we know what to do
if (count($items) == $numToChoose) {
$results[] = $comb + $items;
return;
}
// The recursive cases: either use the first element or not and find combinations of the rest
$val = reset($items);
$key = key($items);
unset($items[$key]);
// not using it
combinations($items, $numToChoose, $results, $comb);
// using it
$comb[$key] = $val;
combinations($items, $numToChoose - 1, $results, $comb);
}
// Do a test run
$combs = [];
combinations([1=>1, 2=>2, 3=>3], 2, $combs);
var_dump($perms);
This results in the output:
array(3) {
[0]=>
array(2) {
[2]=>
int(2)
[3]=>
int(3)
}
[1]=>
array(2) {
[1]=>
int(1)
[3]=>
int(3)
}
[2]=>
array(2) {
[1]=>
int(1)
[2]=>
int(2)
}
}
I needed a combining function that included subsets, so I took #Nguyen Van Vinh's answer and modified it for my needs.
If you pass [1,2,3,4] to the function, it returns every unique combination and subset, sorted:
[
[1,2,3,4], [1,2,3], [1,2,4], [1,3,4], [2,3,4], [1,2], [1,3], [1,4], [2,3], [2,4], [3,4], [1], [2], [3], [4]
]
Here's the function:
function get_combinations_with_length( $numbers, $length ){
$result = array();
$stack = array();
// every combinations can be ordered
sort($numbers);
// startup
array_push($stack, array(
'store' => array(),
'options' => $numbers,
));
while (true) {
// pop a item
$item = array_pop($stack);
// end of stack
if (!$item) break;
// valid store
if ($length <= count($item['store'])) {
$result[] = $item['store'];
continue;
}
// bypass when options are not enough
if (count($item['store']) + count($item['options']) < $length) {
continue;
}
foreach ($item['options'] as $i=>$n) {
$newStore = $item['store'];
$newStore[] = $n;
// every combine can be ordered, so accept only options that are greater than store numbers
$newOptions = array_slice($item['options'], $i + 1);
// array_unshift to sort numerically, array_push to reverse
array_unshift($stack, array(
'store' => $newStore,
'options' => $newOptions,
));
}
}
return $result;
}
function get_all_combinations( $numbers ){
$length = count($numbers);
$result = [];
while ($length > 0) {
$result = array_merge($result, get_combinations_with_length( $numbers, $length ));
$length--;
}
return $result;
}
$numbers = [1,2,3,4];
$result = get_all_combinations($numbers);
echo 'START: '.json_encode( $numbers ).'<br><br>';
echo 'RESULT: '.json_encode( $result ).'<br><br>';
echo '('.count($result).' combination subsets found)';
I have an array of 7 numbers (1,2,3,4,5,6,7) and I want to choose 5 of the numbers like
(1,2,3,4,5), (1,2,3,4,6), (1,2,3,4,7).
Note that (1,2,3,4,5) is equal to (4,5,3,1,2), so only one of those should be included in the output.
I would like to know if there is a function in PHP or any algorithm that can do this ?
I have no idea where to start from.
Can you help me ?
I want all the combinations of 7 given numbers ( they are taken from an array ) put into 5 slots, disregarding order.
You can use the solution found here http://stereofrog.com/blok/on/070910.
Incase the link goes down here's the code....
class Combinations implements Iterator
{
protected $c = null;
protected $s = null;
protected $n = 0;
protected $k = 0;
protected $pos = 0;
function __construct($s, $k) {
if(is_array($s)) {
$this->s = array_values($s);
$this->n = count($this->s);
} else {
$this->s = (string) $s;
$this->n = strlen($this->s);
}
$this->k = $k;
$this->rewind();
}
function key() {
return $this->pos;
}
function current() {
$r = array();
for($i = 0; $i < $this->k; $i++)
$r[] = $this->s[$this->c[$i]];
return is_array($this->s) ? $r : implode('', $r);
}
function next() {
if($this->_next())
$this->pos++;
else
$this->pos = -1;
}
function rewind() {
$this->c = range(0, $this->k);
$this->pos = 0;
}
function valid() {
return $this->pos >= 0;
}
protected function _next() {
$i = $this->k - 1;
while ($i >= 0 && $this->c[$i] == $this->n - $this->k + $i)
$i--;
if($i < 0)
return false;
$this->c[$i]++;
while($i++ < $this->k - 1)
$this->c[$i] = $this->c[$i - 1] + 1;
return true;
}
}
foreach(new Combinations("1234567", 5) as $substring)
echo $substring, ' ';
12345 12346 12347 12356 12357 12367 12456 12457 12467 12567 13456 13457 13467 13567 14567 23456 23457 23467 23567 24567 34567
<?php
echo "<pre>";
$test = array("test_1","test_2","test_3");
// Get Combination
$return = uniqueCombination($test);
//Sort
sort($return);
//Pretty Print
print_r(array_map(function($v){ return implode(",", $v); }, $return));
function uniqueCombination($in, $minLength = 1, $max = 2000) {
$count = count($in);
$members = pow(2, $count);
$return = array();
for($i = 0; $i < $members; $i ++) {
$b = sprintf("%0" . $count . "b", $i);
$out = array();
for($j = 0; $j < $count; $j ++) {
$b{$j} == '1' and $out[] = $in[$j];
}
count($out) >= $minLength && count($out) <= $max and $return[] = $out;
}
return $return;
}
?>
output
Array
(
[0] => test_1
[1] => test_2
[2] => test_3
[3] => test_1,test_2
[4] => test_1,test_3
[5] => test_2,test_3
[6] => test_1,test_2,test_3
)
The Math_Combinatorics in PEAR repository does exactly what you want:
A package that returns all the combinations and permutations, without
repetition, of a given set and subset size. Associative arrays are
preserved.
require_once 'Math/Combinatorics.php';
$combinatorics = new Math_Combinatorics;
$input = array(1, 2, 3, 4, 5, 6, 7);
$output = $combinatorics->combinations($input, 5); // 5 is the subset size
// 1,2,3,4,5
// 1,2,3,4,6
// 1,2,3,4,7
// 1,2,3,5,6
// 1,2,3,5,7
// 1,2,3,6,7
// 1,2,4,5,6
// 1,2,4,5,7
// 1,2,4,6,7
// 1,2,5,6,7
// 1,3,4,5,6
// 1,3,4,5,7
// 1,3,4,6,7
// 1,3,5,6,7
// 1,4,5,6,7
// 2,3,4,5,6
// 2,3,4,5,7
// 2,3,4,6,7
// 2,3,5,6,7
// 2,4,5,6,7
// 3,4,5,6,7
Another solution that bases on stack. It's quit fast but eats much memory.
Hope that helps someone.
In detail:
function _combine($numbers, $length)
{
$combinations = array();
$stack = array();
// every combinations can be ordered
sort($numbers);
// startup
array_push($stack, array(
'store' => array(),
'options' => $numbers,
));
while (true) {
// pop a item
$item = array_pop($stack);
// end of stack
if (!$item) {
break;
}
// valid store
if ($length <= count($item['store'])) {
$combinations[] = $item['store'];
continue;
}
// bypass when options are not enough
if (count($item['store']) + count($item['options']) < $length) {
continue;
}
foreach ($item['options'] as $index => $n) {
$newStore = $item['store'];
$newStore[] = $n;
// every combine can be ordered
// so accept only options which is greater than store numbers
$newOptions = array_slice($item['options'], $index + 1);
// push new items
array_push($stack, array(
'store' => $newStore,
'options' => $newOptions,
));
}
}
return $combinations;
}
Improved this answer to work with associative array as well:
function uniqueCombination($values, $minLength = 1, $maxLength = 2000) {
$count = count($values);
$size = pow(2, $count);
$keys = array_keys($values);
$return = [];
for($i = 0; $i < $size; $i ++) {
$b = sprintf("%0" . $count . "b", $i);
$out = [];
for($j = 0; $j < $count; $j ++) {
if ($b[$j] == '1') {
$out[$keys[$j]] = $values[$keys[$j]];
}
}
if (count($out) >= $minLength && count($out) <= $maxLength) {
$return[] = $out;
}
}
return $return;
}
Eg:
print_r(uniqueCombination([
'a' => 'xyz',
'b' => 'pqr',
]);
Result:
Array
(
[0] => Array
(
[b] => pqr
)
[1] => Array
(
[a] => xyz
)
[2] => Array
(
[a] => xyz
[b] => pqr
)
)
It will still work for non-associative arrays:
print_r(uniqueCombination(['a', 'b']);
Result:
Array
(
[0] => Array
(
[1] => b
)
[1] => Array
(
[0] => a
)
[2] => Array
(
[0] => a
[1] => b
)
)
New solution which optimizes speed and memory for combining algorithm
Mindset: generate combinations K numbers of Array of numbers. New solution will use K 'for' statements. One 'for' One number.
Such as: $K = 5 mean that 5 of 'for' statements is used
$total = count($array);
$i0 = -1;
for ($i1 = $i0 + 1; $i1 < $total; $i1++) {
for ($i2 = $i1 + 1; $i2 < $total; $i2++) {
for ($i3 = $i2 + 1; $i3 < $total; $i3++) {
for ($i4 = $i3 + 1; $i4 < $total; $i4++) {
for ($i5 = $i4 + 1; $i5 < $total; $i5++) {
$record = array();
for ($i = 1; $i <= $k; $i++) {
$t = "i$i";
$record[] = $array[$$t];
}
$callback($record);
}
}
}
}
}
And detail of code that generated the real code that will be execute by eval() function
function combine($array, $k, $callback)
{
$total = count($array);
$init = '
$i0 = -1;
';
$sample = '
for($i{current} = $i{previous} + 1; $i{current} < $total; $i{current}++ ) {
{body}
}
';
$do = '
$record = array();
for ($i = 1; $i <= $k; $i++) {
$t = "i$i";
$record[] = $array[$$t];
}
$callback($record);
';
$for = '';
for ($i = $k; $i >= 1; $i--) {
switch ($i) {
case $k:
$for = str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $do], $sample);
break;
case 1:
$for = $init . str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $for], $sample);
break;
default:
$for = str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $for], $sample);
break;
}
}
// execute
eval($for);
}
How to combine K numbers of Array
$k = 5;
$array = array(1, 2, 3, 4, 5, 6, 7);
$callback = function ($record) {
echo implode($record) . "\n";
};
combine($array, $k, $callback);
I found the other answers here confusing or overly complicated, so I wrote my own. I think this is a simple solution with a recursive method. The basic idea is that you go through your array and for each item decide whether or not it is in the combination (actually, you don't decide, you recursively try both ways). You make this choice for the first item and then combine it with the recursively generated combinations of the rest of the array. This solution fills a result array with every combination of your array as a sub-array. It uses the items in order and it preserves associations, including with numeric keys.
function combinations(array $items, int $numToChoose, array &$results, $comb = []): void {
if (count($items) < $numToChoose) {
throw new \Exception("Asked to choose $numToChoose items from an array of length ". count($items));
}
// if nothing left to choose, we have a complete combination
if ($numToChoose === 0) {
$results[] = $comb;
return;
}
// if we have to choose everything at this point, then we know what to do
if (count($items) == $numToChoose) {
$results[] = $comb + $items;
return;
}
// The recursive cases: either use the first element or not and find combinations of the rest
$val = reset($items);
$key = key($items);
unset($items[$key]);
// not using it
combinations($items, $numToChoose, $results, $comb);
// using it
$comb[$key] = $val;
combinations($items, $numToChoose - 1, $results, $comb);
}
// Do a test run
$combs = [];
combinations([1=>1, 2=>2, 3=>3], 2, $combs);
var_dump($perms);
This results in the output:
array(3) {
[0]=>
array(2) {
[2]=>
int(2)
[3]=>
int(3)
}
[1]=>
array(2) {
[1]=>
int(1)
[3]=>
int(3)
}
[2]=>
array(2) {
[1]=>
int(1)
[2]=>
int(2)
}
}
I needed a combining function that included subsets, so I took #Nguyen Van Vinh's answer and modified it for my needs.
If you pass [1,2,3,4] to the function, it returns every unique combination and subset, sorted:
[
[1,2,3,4], [1,2,3], [1,2,4], [1,3,4], [2,3,4], [1,2], [1,3], [1,4], [2,3], [2,4], [3,4], [1], [2], [3], [4]
]
Here's the function:
function get_combinations_with_length( $numbers, $length ){
$result = array();
$stack = array();
// every combinations can be ordered
sort($numbers);
// startup
array_push($stack, array(
'store' => array(),
'options' => $numbers,
));
while (true) {
// pop a item
$item = array_pop($stack);
// end of stack
if (!$item) break;
// valid store
if ($length <= count($item['store'])) {
$result[] = $item['store'];
continue;
}
// bypass when options are not enough
if (count($item['store']) + count($item['options']) < $length) {
continue;
}
foreach ($item['options'] as $i=>$n) {
$newStore = $item['store'];
$newStore[] = $n;
// every combine can be ordered, so accept only options that are greater than store numbers
$newOptions = array_slice($item['options'], $i + 1);
// array_unshift to sort numerically, array_push to reverse
array_unshift($stack, array(
'store' => $newStore,
'options' => $newOptions,
));
}
}
return $result;
}
function get_all_combinations( $numbers ){
$length = count($numbers);
$result = [];
while ($length > 0) {
$result = array_merge($result, get_combinations_with_length( $numbers, $length ));
$length--;
}
return $result;
}
$numbers = [1,2,3,4];
$result = get_all_combinations($numbers);
echo 'START: '.json_encode( $numbers ).'<br><br>';
echo 'RESULT: '.json_encode( $result ).'<br><br>';
echo '('.count($result).' combination subsets found)';
I have a problem with an advanced loop, this are my arrays
$array1 = array(1,2,3);
$array2 = array(4,5);
$array3 = array(6,7,8,9);
$array4 = array(10,11);
I want to loop with the following result:
1,4,6,10
1,4,6,11
1,4,7,10
1,5,7,11
With the last: 3,5,8,11
How can I do that?
Solution for a variable number of arrays. Can probably be written a bit shorter, but I leave that to you. ;)
<?php
$array1 = array(1,2,3);
$array2 = array(4,5);
$array3 = array(6,7,8,9);
$array4 = array(10,11);
function turboArray()
{
$arrays = func_get_args();
$indexes = array_fill(0, count($arrays), 0);
function turboSubArray(&$arrays, &$indexes, $l){
for ($a = 0; $a < count($arrays[$l]); $a++){
$indexes[$l] = $a;
if ($l == count($arrays) - 1) {
for ($i = 0; $i < count($indexes); $i++)
{
echo $arrays[$i][$indexes[$i]];
if ($i == count($indexes) - 1){
echo "\n<br/>";
$indexes[$i] = 0;
if ($i == 0) return;
}
else {
echo ', ';
}
}
} else if ($l < count($indexes)) {
turboSubArray($arrays, $indexes, $l + 1);
}
}
}
$l = 0;
turboSubArray($arrays, $indexes, $l);
}
turboArray($array1, $array2, $array3, $array4);
This should do it... ?
foreach ($array1 as $first) {
foreach ($array2 as $second) {
foreach ($array3 as $third) {
foreach ($array4 as $fourth) {
echo "$first $second $third $fourth";
}
}
}
}
I got bored and decided to overengineer a bit. Enjoy.
class CrossJoin implements Iterator {
private $arrays = array();
private $index = 0;
public function __construct(/* $array1, ... */) {
foreach (func_get_args() as $arr) {
// ArrayIterator's iteration stuff is cleaner than arrays',
// and less prone to breakage when objects are passed around
if (count($arr)) $this->arrays[] = new ArrayIterator($arr);
}
// if any of the arrays were empty, a cross join should fail.
// fudge a single empty array to prevent special-casing later
if (count($this->arrays) !== func_num_args()) {
$this->arrays = array(new ArrayIterator(array()));
}
}
public function next() {
for ($i = count($this->arrays) - 1; $i >= 0; --$i) {
// carry til we don't have to anymore
$place = $this->arrays[$i];
$place->next();
if ($place->valid()) break;
}
// if $i<0, then we carried right off the edge of the list.
// don't let $arrays[0] be reset, cause that's our indicator
// that we're done.
if ($i<0) return;
++$this->index;
for (++$i; $i < count($this->arrays); ++$i) {
$this->arrays[$i]->rewind();
}
}
public function current() {
$result = array();
foreach ($this->arrays as $arr) { $result[] = $arr->current(); }
return $result;
}
public function key() { return $this->index; }
public function valid() {
return !empty($this->arrays) && $this->arrays[0]->valid();
}
public function rewind() {
foreach ($this->arrays as $arr) $arr->rewind();
$this->index = 0;
}
}
$combos = new CrossJoin(
array(1, 2, 3),
array(4, 5),
array(6, 7, 8, 9),
array(10, 11)
);
foreach ($combos as $combo) {
echo implode(', ', $combo), "\n";
}
Hope that helps:
for ($i = 0; $i < count($a1); ++i) {
for ($j = 0; $j < count($a2); ++j) {
for ($k = 0; $k < count($a3); ++k) {
for ($l = 0; $l < count($a4); ++l) {
echo $a1[$i] . ' ' . $a2[$j] . ' ' . $a3[$k] . ' ' . $a4[$l] . '\n';
}
}
}
}
Cheers!
You are looking for the PHP array_merge function.
I have an array of 7 numbers (1,2,3,4,5,6,7) and I want to choose 5 of the numbers like
(1,2,3,4,5), (1,2,3,4,6), (1,2,3,4,7).
Note that (1,2,3,4,5) is equal to (4,5,3,1,2), so only one of those should be included in the output.
I would like to know if there is a function in PHP or any algorithm that can do this ?
I have no idea where to start from.
Can you help me ?
I want all the combinations of 7 given numbers ( they are taken from an array ) put into 5 slots, disregarding order.
You can use the solution found here http://stereofrog.com/blok/on/070910.
Incase the link goes down here's the code....
class Combinations implements Iterator
{
protected $c = null;
protected $s = null;
protected $n = 0;
protected $k = 0;
protected $pos = 0;
function __construct($s, $k) {
if(is_array($s)) {
$this->s = array_values($s);
$this->n = count($this->s);
} else {
$this->s = (string) $s;
$this->n = strlen($this->s);
}
$this->k = $k;
$this->rewind();
}
function key() {
return $this->pos;
}
function current() {
$r = array();
for($i = 0; $i < $this->k; $i++)
$r[] = $this->s[$this->c[$i]];
return is_array($this->s) ? $r : implode('', $r);
}
function next() {
if($this->_next())
$this->pos++;
else
$this->pos = -1;
}
function rewind() {
$this->c = range(0, $this->k);
$this->pos = 0;
}
function valid() {
return $this->pos >= 0;
}
protected function _next() {
$i = $this->k - 1;
while ($i >= 0 && $this->c[$i] == $this->n - $this->k + $i)
$i--;
if($i < 0)
return false;
$this->c[$i]++;
while($i++ < $this->k - 1)
$this->c[$i] = $this->c[$i - 1] + 1;
return true;
}
}
foreach(new Combinations("1234567", 5) as $substring)
echo $substring, ' ';
12345 12346 12347 12356 12357 12367 12456 12457 12467 12567 13456 13457 13467 13567 14567 23456 23457 23467 23567 24567 34567
<?php
echo "<pre>";
$test = array("test_1","test_2","test_3");
// Get Combination
$return = uniqueCombination($test);
//Sort
sort($return);
//Pretty Print
print_r(array_map(function($v){ return implode(",", $v); }, $return));
function uniqueCombination($in, $minLength = 1, $max = 2000) {
$count = count($in);
$members = pow(2, $count);
$return = array();
for($i = 0; $i < $members; $i ++) {
$b = sprintf("%0" . $count . "b", $i);
$out = array();
for($j = 0; $j < $count; $j ++) {
$b{$j} == '1' and $out[] = $in[$j];
}
count($out) >= $minLength && count($out) <= $max and $return[] = $out;
}
return $return;
}
?>
output
Array
(
[0] => test_1
[1] => test_2
[2] => test_3
[3] => test_1,test_2
[4] => test_1,test_3
[5] => test_2,test_3
[6] => test_1,test_2,test_3
)
The Math_Combinatorics in PEAR repository does exactly what you want:
A package that returns all the combinations and permutations, without
repetition, of a given set and subset size. Associative arrays are
preserved.
require_once 'Math/Combinatorics.php';
$combinatorics = new Math_Combinatorics;
$input = array(1, 2, 3, 4, 5, 6, 7);
$output = $combinatorics->combinations($input, 5); // 5 is the subset size
// 1,2,3,4,5
// 1,2,3,4,6
// 1,2,3,4,7
// 1,2,3,5,6
// 1,2,3,5,7
// 1,2,3,6,7
// 1,2,4,5,6
// 1,2,4,5,7
// 1,2,4,6,7
// 1,2,5,6,7
// 1,3,4,5,6
// 1,3,4,5,7
// 1,3,4,6,7
// 1,3,5,6,7
// 1,4,5,6,7
// 2,3,4,5,6
// 2,3,4,5,7
// 2,3,4,6,7
// 2,3,5,6,7
// 2,4,5,6,7
// 3,4,5,6,7
Another solution that bases on stack. It's quit fast but eats much memory.
Hope that helps someone.
In detail:
function _combine($numbers, $length)
{
$combinations = array();
$stack = array();
// every combinations can be ordered
sort($numbers);
// startup
array_push($stack, array(
'store' => array(),
'options' => $numbers,
));
while (true) {
// pop a item
$item = array_pop($stack);
// end of stack
if (!$item) {
break;
}
// valid store
if ($length <= count($item['store'])) {
$combinations[] = $item['store'];
continue;
}
// bypass when options are not enough
if (count($item['store']) + count($item['options']) < $length) {
continue;
}
foreach ($item['options'] as $index => $n) {
$newStore = $item['store'];
$newStore[] = $n;
// every combine can be ordered
// so accept only options which is greater than store numbers
$newOptions = array_slice($item['options'], $index + 1);
// push new items
array_push($stack, array(
'store' => $newStore,
'options' => $newOptions,
));
}
}
return $combinations;
}
Improved this answer to work with associative array as well:
function uniqueCombination($values, $minLength = 1, $maxLength = 2000) {
$count = count($values);
$size = pow(2, $count);
$keys = array_keys($values);
$return = [];
for($i = 0; $i < $size; $i ++) {
$b = sprintf("%0" . $count . "b", $i);
$out = [];
for($j = 0; $j < $count; $j ++) {
if ($b[$j] == '1') {
$out[$keys[$j]] = $values[$keys[$j]];
}
}
if (count($out) >= $minLength && count($out) <= $maxLength) {
$return[] = $out;
}
}
return $return;
}
Eg:
print_r(uniqueCombination([
'a' => 'xyz',
'b' => 'pqr',
]);
Result:
Array
(
[0] => Array
(
[b] => pqr
)
[1] => Array
(
[a] => xyz
)
[2] => Array
(
[a] => xyz
[b] => pqr
)
)
It will still work for non-associative arrays:
print_r(uniqueCombination(['a', 'b']);
Result:
Array
(
[0] => Array
(
[1] => b
)
[1] => Array
(
[0] => a
)
[2] => Array
(
[0] => a
[1] => b
)
)
New solution which optimizes speed and memory for combining algorithm
Mindset: generate combinations K numbers of Array of numbers. New solution will use K 'for' statements. One 'for' One number.
Such as: $K = 5 mean that 5 of 'for' statements is used
$total = count($array);
$i0 = -1;
for ($i1 = $i0 + 1; $i1 < $total; $i1++) {
for ($i2 = $i1 + 1; $i2 < $total; $i2++) {
for ($i3 = $i2 + 1; $i3 < $total; $i3++) {
for ($i4 = $i3 + 1; $i4 < $total; $i4++) {
for ($i5 = $i4 + 1; $i5 < $total; $i5++) {
$record = array();
for ($i = 1; $i <= $k; $i++) {
$t = "i$i";
$record[] = $array[$$t];
}
$callback($record);
}
}
}
}
}
And detail of code that generated the real code that will be execute by eval() function
function combine($array, $k, $callback)
{
$total = count($array);
$init = '
$i0 = -1;
';
$sample = '
for($i{current} = $i{previous} + 1; $i{current} < $total; $i{current}++ ) {
{body}
}
';
$do = '
$record = array();
for ($i = 1; $i <= $k; $i++) {
$t = "i$i";
$record[] = $array[$$t];
}
$callback($record);
';
$for = '';
for ($i = $k; $i >= 1; $i--) {
switch ($i) {
case $k:
$for = str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $do], $sample);
break;
case 1:
$for = $init . str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $for], $sample);
break;
default:
$for = str_replace(['{current}', '{previous}', '{body}'], [$i, $i - 1, $for], $sample);
break;
}
}
// execute
eval($for);
}
How to combine K numbers of Array
$k = 5;
$array = array(1, 2, 3, 4, 5, 6, 7);
$callback = function ($record) {
echo implode($record) . "\n";
};
combine($array, $k, $callback);
I found the other answers here confusing or overly complicated, so I wrote my own. I think this is a simple solution with a recursive method. The basic idea is that you go through your array and for each item decide whether or not it is in the combination (actually, you don't decide, you recursively try both ways). You make this choice for the first item and then combine it with the recursively generated combinations of the rest of the array. This solution fills a result array with every combination of your array as a sub-array. It uses the items in order and it preserves associations, including with numeric keys.
function combinations(array $items, int $numToChoose, array &$results, $comb = []): void {
if (count($items) < $numToChoose) {
throw new \Exception("Asked to choose $numToChoose items from an array of length ". count($items));
}
// if nothing left to choose, we have a complete combination
if ($numToChoose === 0) {
$results[] = $comb;
return;
}
// if we have to choose everything at this point, then we know what to do
if (count($items) == $numToChoose) {
$results[] = $comb + $items;
return;
}
// The recursive cases: either use the first element or not and find combinations of the rest
$val = reset($items);
$key = key($items);
unset($items[$key]);
// not using it
combinations($items, $numToChoose, $results, $comb);
// using it
$comb[$key] = $val;
combinations($items, $numToChoose - 1, $results, $comb);
}
// Do a test run
$combs = [];
combinations([1=>1, 2=>2, 3=>3], 2, $combs);
var_dump($perms);
This results in the output:
array(3) {
[0]=>
array(2) {
[2]=>
int(2)
[3]=>
int(3)
}
[1]=>
array(2) {
[1]=>
int(1)
[3]=>
int(3)
}
[2]=>
array(2) {
[1]=>
int(1)
[2]=>
int(2)
}
}
I needed a combining function that included subsets, so I took #Nguyen Van Vinh's answer and modified it for my needs.
If you pass [1,2,3,4] to the function, it returns every unique combination and subset, sorted:
[
[1,2,3,4], [1,2,3], [1,2,4], [1,3,4], [2,3,4], [1,2], [1,3], [1,4], [2,3], [2,4], [3,4], [1], [2], [3], [4]
]
Here's the function:
function get_combinations_with_length( $numbers, $length ){
$result = array();
$stack = array();
// every combinations can be ordered
sort($numbers);
// startup
array_push($stack, array(
'store' => array(),
'options' => $numbers,
));
while (true) {
// pop a item
$item = array_pop($stack);
// end of stack
if (!$item) break;
// valid store
if ($length <= count($item['store'])) {
$result[] = $item['store'];
continue;
}
// bypass when options are not enough
if (count($item['store']) + count($item['options']) < $length) {
continue;
}
foreach ($item['options'] as $i=>$n) {
$newStore = $item['store'];
$newStore[] = $n;
// every combine can be ordered, so accept only options that are greater than store numbers
$newOptions = array_slice($item['options'], $i + 1);
// array_unshift to sort numerically, array_push to reverse
array_unshift($stack, array(
'store' => $newStore,
'options' => $newOptions,
));
}
}
return $result;
}
function get_all_combinations( $numbers ){
$length = count($numbers);
$result = [];
while ($length > 0) {
$result = array_merge($result, get_combinations_with_length( $numbers, $length ));
$length--;
}
return $result;
}
$numbers = [1,2,3,4];
$result = get_all_combinations($numbers);
echo 'START: '.json_encode( $numbers ).'<br><br>';
echo 'RESULT: '.json_encode( $result ).'<br><br>';
echo '('.count($result).' combination subsets found)';
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.
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);
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
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;
}
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:
$data = array(
array('Amazing', 'Wonderful'),
array('benefit', 'offer', 'reward'),
array('Amazing', 'Wonderful')
);
Then it will print something like this:
Amazing - benefit - Wonderful
Amazing - offer - Wonderful
Amazing - reward - Wonderful
Wonderful - benefit - Amazing
Wonderful - offer - Amazing
Wonderful - reward - Amazing
foreach($parentArray as $value) {
foreach($subArray as $value2) {
$comboArray[] = array($value, $value2);
}
}
Don't judge me..
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;
}
}
}
}
#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', $array_of_arrays);
function array_comb($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 $result;
}
I had to make combinations from product options. This solution uses recursion and works with 2D array:
function options_combinations($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(' ', $combination)."\n";
}
Elegant implementation based on native Python function itertools.product
function direct_product(array ...$arrays)
{
$result = [[]];
foreach ($arrays as $array) {
$tmp = [];
foreach ($result as $x) {
foreach ($array as $y) {
$tmp[] = array_merge($x, [$y]);
}
}
$result = $tmp;
}
return $result;
}