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I have numbers, from 0 to 8. I would like in result, all possible sets of those numbers, each set should use all numbers, each number can occur only once in a set.
I would like to see solution made in PHP that could print out result. Or, at least, I would like some refreshment in theory of combinatorics, as I have long forgotten it. What is the formula to calculate how many permutations will there be?
Example sets:
0-1-2-3-4-5-6-7-8
0-1-2-3-4-5-6-8-7
0-1-2-3-4-5-8-6-7
0-1-2-3-4-8-5-6-7
0-1-2-3-8-4-5-6-7
0-1-2-8-3-4-5-6-7
and so on...
You're looking for the permutations formula:
nPk = n!/(n-k)!
In your case, you have 9 entries and you want to choose all of them, that's 9P9 = 9! = 362880
You can find a PHP algorithm to permutate in recipe 4.26 of O'Reilly's "PHP Cookbook".
pc_permute(array(0, 1, 2, 3, 4, 5, 7, 8));
Copied in from O'Reilly:
function pc_permute($items, $perms = array( )) {
if (empty($items)) {
print join(' ', $perms) . "\n";
} else {
for ($i = count($items) - 1; $i >= 0; --$i) {
$newitems = $items;
$newperms = $perms;
list($foo) = array_splice($newitems, $i, 1);
array_unshift($newperms, $foo);
pc_permute($newitems, $newperms);
}
}
}
Since PHP 5.5 you can use Generators. Generators save a lot of memory and are way faster (more than half compared to pc_permute()). So if you have any chance of having PHP 5.5 installed, you definitely want Generators.
This snipped is ported from Python: https://stackoverflow.com/a/104436/3745311
function permutations(array $elements)
{
if (count($elements) <= 1) {
yield $elements;
} else {
foreach (permutations(array_slice($elements, 1)) as $permutation) {
foreach (range(0, count($elements) - 1) as $i) {
yield array_merge(
array_slice($permutation, 0, $i),
[$elements[0]],
array_slice($permutation, $i)
);
}
}
}
}
Sample usage:
$list = ['a', 'b', 'c'];
foreach (permutations($list) as $permutation) {
echo implode(',', $permutation) . PHP_EOL;
}
Output:
a,b,c
b,a,c
b,c,a
a,c,b
c,a,b
c,b,a
Since this question often comes up in Google Search results, here's a modified version of the accepted answer that returns all combinations in an array and passes them as a return value of the function.
function pc_permute($items, $perms = array( )) {
if (empty($items)) {
$return = array($perms);
} else {
$return = array();
for ($i = count($items) - 1; $i >= 0; --$i) {
$newitems = $items;
$newperms = $perms;
list($foo) = array_splice($newitems, $i, 1);
array_unshift($newperms, $foo);
$return = array_merge($return, pc_permute($newitems, $newperms));
}
}
return $return;
}
To use:
$value = array('1', '2', '3');
print_r(pc_permute($value));
I've something that You may like
function combination_number($k,$n){
$n = intval($n);
$k = intval($k);
if ($k > $n){
return 0;
} elseif ($n == $k) {
return 1;
} else {
if ($k >= $n - $k){
$l = $k+1;
for ($i = $l+1 ; $i <= $n ; $i++)
$l *= $i;
$m = 1;
for ($i = 2 ; $i <= $n-$k ; $i++)
$m *= $i;
} else {
$l = ($n-$k) + 1;
for ($i = $l+1 ; $i <= $n ; $i++)
$l *= $i;
$m = 1;
for ($i = 2 ; $i <= $k ; $i++)
$m *= $i;
}
}
return $l/$m;
}
function array_combination($le, $set){
$lk = combination_number($le, count($set));
$ret = array_fill(0, $lk, array_fill(0, $le, '') );
$temp = array();
for ($i = 0 ; $i < $le ; $i++)
$temp[$i] = $i;
$ret[0] = $temp;
for ($i = 1 ; $i < $lk ; $i++){
if ($temp[$le-1] != count($set)-1){
$temp[$le-1]++;
} else {
$od = -1;
for ($j = $le-2 ; $j >= 0 ; $j--)
if ($temp[$j]+1 != $temp[$j+1]){
$od = $j;
break;
}
if ($od == -1)
break;
$temp[$od]++;
for ($j = $od+1 ; $j < $le ; $j++)
$temp[$j] = $temp[$od]+$j-$od;
}
$ret[$i] = $temp;
}
for ($i = 0 ; $i < $lk ; $i++)
for ($j = 0 ; $j < $le ; $j++)
$ret[$i][$j] = $set[$ret[$i][$j]];
return $ret;
}
Here is how to use it:
To get the number of combinations:
combination_number(3,10); // returns number of combinations of ten-elements set.
To get all possible combinations:
$mySet = array("A","B","C","D","E","F");
array_combination(3, $mySet); // returns all possible combinations of 3 elements of six-elements set.
Hope You make use of that.
I've ported the Python itertools code listed here (using generators). The advantage over the solutions posted so far is that it allows you to specify r (permutation size).
function permutations($pool, $r = null) {
$n = count($pool);
if ($r == null) {
$r = $n;
}
if ($r > $n) {
return;
}
$indices = range(0, $n - 1);
$cycles = range($n, $n - $r + 1, -1); // count down
yield array_slice($pool, 0, $r);
if ($n <= 0) {
return;
}
while (true) {
$exit_early = false;
for ($i = $r;$i--;$i >= 0) {
$cycles[$i]-= 1;
if ($cycles[$i] == 0) {
// Push whatever is at index $i to the end, move everything back
if ($i < count($indices)) {
$removed = array_splice($indices, $i, 1);
array_push($indices, $removed[0]);
}
$cycles[$i] = $n - $i;
} else {
$j = $cycles[$i];
// Swap indices $i & -$j.
$i_val = $indices[$i];
$neg_j_val = $indices[count($indices) - $j];
$indices[$i] = $neg_j_val;
$indices[count($indices) - $j] = $i_val;
$result = [];
$counter = 0;
foreach ($indices as $indx) {
array_push($result, $pool[$indx]);
$counter++;
if ($counter == $r) break;
}
yield $result;
$exit_early = true;
break;
}
}
if (!$exit_early) {
break; // Outer while loop
}
}
}
It works for me, but no promises!
Example usage:
$result = iterator_to_array(permutations([1, 2, 3, 4], 3));
foreach ($result as $row) {
print implode(", ", $row) . "\n";
}
This is my version of class. This class builds and returns permutated array as result
class Permutation {
private $result;
public function getResult() {
return $this->result;
}
public function permute($source, $permutated=array()) {
if (empty($permutated)){
$this->result = array();
}
if (empty($source)){
$this->result[] = $permutated;
} else {
for($i=0; $i<count($source); $i++){
$new_permutated = $permutated;
$new_permutated[] = $source[$i];
$new_source = array_merge(array_slice($source,0,$i),array_slice($source,$i+1));
$this->permute($new_source, $new_permutated);
}
}
return $this;
}
}
$arr = array(1,2,3,4,5);
$p = new Permutation();
print_r($p->permute($arr)->getResult());
The last three lines to test my class.
This is a simple recursive function that prints all permutations (written in pseudocode)
function rec(n, k) {
if (k == n) {
for i = 0 to n-1
print(perm[i], ' ');
print('\n');
}
else {
for i = 0 to n-1 {
if (not used[i]) {
used[i] = true;
perm[k] = i;
rec(n, k+1);
used[i] = false;
}
}
}
}
And it is called like this:
rec(9, 0);
Lexicographical order. There is no recursion. Almost no limits for array length.
There is no sort. It's running rather fast. It's easy to understand.
Minus: it gives a notice, but you can add a condition to start compare with the second element or error_reporting(0).
$a = array(
1,
2,
3,
4,
5
);
$b = array_reverse($a);
print_r($a);
//here need "br"
while ($a != $b)
{
foreach(array_reverse($a, true) as $k => $v)
{
if ($v < $a[$k + 1])
{
foreach(array_reverse($a, true) as $ka => $val)
{
if ($val > $v) break;
}
$ch = $a[$k];
$a[$k] = $a[$ka];
$a[$ka] = $ch;
$c = array_slice($a, 0, $k + 1);
print_r($a = array_merge($c, array_reverse(array_slice($a, $k + 1))));
//here need "br"
break;
}
}
}
You're basically talking about permutations where both n and k are 9 so you'll have 9! different permutations; see this: http://en.wikipedia.org/wiki/Permutation.
Here is my proposal, hope a little bit clearer than accepted answer.
function permutate($elements, $perm = array(), &$permArray = array())
{
if(empty($elements))
{
array_push($permArray,$perm); return;
}
for($i=0;$i<=count($elements)-1;$i++)
{
array_push($perm,$elements[$i]);
$tmp = $elements; array_splice($tmp,$i,1);
permutate($tmp,$perm,$permArray);
array_pop($perm);
}
return $permArray;
}
and usage:
$p = permutate(array('a','b','c'));
foreach($p as $perm)
print join(",",$perm)."|\n";
//function call
print_r(combinations([1,2,3,4,5,6,7,8,9,10,11,12,13]));
/**
* #param $mainArray
* #param int $size - optional
* #param array $combinations - optional
* #return mixed
*/
function combinations($mainArray, $size = 3, $combinations = [])
{
if (empty($combinations)) {
$combinations = $mainArray;
}
if ($size == 1) {
return str_replace('-','',$combinations);;
}
$newCombination = array();
foreach ($mainArray as $key => $val){
foreach ($combinations as $char) {
if(in_array($val, explode('-', $char))){
continue;
}
$newCombination[] = $val . '-' . $char;
}
}
return combinations($mainArray, $size - 1, $newCombination);
}
//========================= Next solution ==================================
function sampling($chars, $size, $combinations = array()) {
# if it's the first iteration, the first set
# of combinations is the same as the set of characters
if (empty($combinations)) {
$combinations = $chars;
}
# we're done if we're at size 1
if ($size == 1) {
return $combinations;
}
# initialise array to put new values in
$new_combinations = array();
# loop through existing combinations and character set to create strings
foreach ($combinations as $combination) {
foreach ($chars as $char) {
$new_combinations[] = $combination .'-'. $char ;
}
}
# call same function again for the next iteration
return $this->sampling($chars, $size - 1, $new_combinations);
}
function array_has_dupes($array) {
return count($array) !== count(array_unique($array));
}
function total() {
// Generate ticket price
$arrfinal = array();
// combinations
$chars = array(1,2,3,4,5,6,7,8,9,10,11,12,13); // for 10 digits
$combinations = $this->sampling($chars, 3);
//print_r($combinations); //exit;
foreach($combinations as $key => $val)
{
$arr = explode('-', $val);//str_split($val);
if(!$this->array_has_dupes($arr)){
$arrfinal[] = str_replace('-', '', $val);
}
}
echo '<pre>'; print_r($arrfinal); echo '</pre>';
}
Simple solution using recursion
function filterElement($element){
if(is_array($element[0])){
return $element[0];
}
# base case
return $element;
}
function permutation($input, $path){
// base case 1
if(count($input) == 0){
return [$path];
}
$output = [];
foreach($input as $index => $num){ # 1, 2,3, 4
$copyPath = $path; # copy the path - []
$copyPath[] = $num; # append the number [1]
# remove the current number
$inputLocal = $input;
unset($inputLocal[$index]); # [2, 3, 4]
$permute = permutation($inputLocal, $copyPath); # call [2, 3, 4], [1]
# for all element find add to output
foreach($permute as $ele){
# filter ouput
$output[] = filterElement($ele);
}
}
return $output;
}
print_r(permutation([1,2,3,4], []));
output
Array
(
[0] => Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
[1] => Array
(
[0] => 1
[1] => 2
[2] => 4
[3] => 3
)
[2] => Array
(
[0] => 1
[1] => 3
[2] => 2
[3] => 4
)
[3] => Array
(
[0] => 1
[1] => 3
[2] => 4
[3] => 2
)
[4] => Array
(
[0] => 1
[1] => 4
[2] => 2
[3] => 3
)
[5] => Array
(
[0] => 1
[1] => 4
[2] => 3
[3] => 2
)
[6] => Array
(
[0] => 2
[1] => 1
[2] => 3
[3] => 4
)
[7] => Array
(
[0] => 2
[1] => 1
[2] => 4
[3] => 3
)
[8] => Array
(
[0] => 2
[1] => 3
[2] => 1
[3] => 4
)
[9] => Array
(
[0] => 2
[1] => 3
[2] => 4
[3] => 1
)
[10] => Array
(
[0] => 2
[1] => 4
[2] => 1
[3] => 3
)
[11] => Array
(
[0] => 2
[1] => 4
[2] => 3
[3] => 1
)
[12] => Array
(
[0] => 3
[1] => 1
[2] => 2
[3] => 4
)
[13] => Array
(
[0] => 3
[1] => 1
[2] => 4
[3] => 2
)
[14] => Array
(
[0] => 3
[1] => 2
[2] => 1
[3] => 4
)
[15] => Array
(
[0] => 3
[1] => 2
[2] => 4
[3] => 1
)
[16] => Array
(
[0] => 3
[1] => 4
[2] => 1
[3] => 2
)
[17] => Array
(
[0] => 3
[1] => 4
[2] => 2
[3] => 1
)
[18] => Array
(
[0] => 4
[1] => 1
[2] => 2
[3] => 3
)
[19] => Array
(
[0] => 4
[1] => 1
[2] => 3
[3] => 2
)
[20] => Array
(
[0] => 4
[1] => 2
[2] => 1
[3] => 3
)
[21] => Array
(
[0] => 4
[1] => 2
[2] => 3
[3] => 1
)
[22] => Array
(
[0] => 4
[1] => 3
[2] => 1
[3] => 2
)
[23] => Array
(
[0] => 4
[1] => 3
[2] => 2
[3] => 1
)
)
I need a PHP code to find longest contiguous sequence of characters in the string. So if b is coming together for maximum number of times your program should echo b and count
Example string:
aaabababbbbbaaaaabbbbbbbbaa
Output must be:
b 8
Using
- preg_match_all to get sequences of repeating characters,
- array_map along with strlen to get the string length of each sequence
- max to get the biggest value in the array.
Consider the following example:
$string = "aaabababbbbbaaaaabbbbbbbbaa";
preg_match_all('#(\w)\1+#',$string,$matches);
print_r($matches);
Will output
Array
(
[0] => Array
(
[0] => aaa
[1] => bbbbb
[2] => aaaaa
[3] => bbbbbbbb
[4] => aa
)
[1] => Array
(
[0] => a
[1] => b
[2] => a
[3] => b
[4] => a
)
)
Next we get the sizes for each string of repeating characters
$sizes = array_map('strlen', $matches[0]);
print_r($sizes);
Will output
Array
(
[0] => 3
[1] => 5
[2] => 5
[3] => 8
[4] => 2
)
Now let's get the biggest value of the $sizes array
print max($sizes);
Will give us
8
We need the key for the max value to pick up the letter
$maxKey = array_keys($sizes, max($sizes));
print $matches[1][$maxKey[0]];
Will output
b
Since you're looking for continuous sequences:
$string = 'aaabababbbbbaaaaabbbbbbbbaa';
$count = strlen($string);
if ($count > 0)
{
$mostFrequentChar = $curChar = $string[0];
$maxFreq = $curFreq = 1;
for ($i = 1; $i < $count; $i++)
{
if ($string[$i] == $curChar)
{
$curFreq++;
if ($curFreq > $maxFreq)
{
$mostFrequentChar = $curChar;
$maxFreq = $curFreq;
}
}
else
{
$curChar = $string[$i];
$curFreq = 1;
}
}
}
echo $mostFrequentChar . ' ' . $maxFreq;
$string = 'aaabababbbbbaaaaabbbbbbbbaa';
$occurrence = [];
$count = strlen($string);
for ($x = 0; $x < $count; $x++) {
if(isset($ocurrence[$string[$x]])) {
$ocurrence[$string[$x]]++;
} else {
$ocurrence[$string[$x]] = 0;
}
}
var_dump($occurrence);
This should do the trick.
<?php
$x = "aaaaaaabbbbbbbaaaacccccccaaaaaaaaaaaaaaaaabbbbbbaaaaadddddddddddddddddddddddddddddddddd";
$count = strlen($x);
$y =array();
$n =0;
$d =1;
$first = $x{1};
for($j = $d;$j < $count;$j++)
{
if($x{$j} == $first )
{
$y[$j] = $x{$j};
$first = $x{$j};
}
elseif($x{$j} != $first )
{
$y[$j] = ",".$x{$j};
$first = $x{$j};
}
}
$xy = implode("",$y);
$xy1 = explode(",",$xy);
$c_count = count($xy1);
$dg = 1;
for($g = 0;$g < $c_count;$g++)
{
$cnt = strlen($xy1[$g]);
$cntm = $xy1[$g];
$replace = $cntm{1};
if($cnt > $dg)
{
$ab = str_replace($cntm,$replace,$cntm);
$dg = $cnt.".".$ab ;
}
}
echo $dg;
?>
This question already has answers here:
PHP array combinations
(8 answers)
Closed 7 years ago.
Hi Guys i have an array like this
$array1 = array('a','b','c','d)
and i want to combine with output like this
'a,b,c'
'a,b,d'
'a,c,d'
'b,c,d'
The problem is to create a function with a variable number and not multiple variable, can anybody help me?
Make a try
[akshay#localhost tmp]$ 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
)
I have numbers, from 0 to 8. I would like in result, all possible sets of those numbers, each set should use all numbers, each number can occur only once in a set.
I would like to see solution made in PHP that could print out result. Or, at least, I would like some refreshment in theory of combinatorics, as I have long forgotten it. What is the formula to calculate how many permutations will there be?
Example sets:
0-1-2-3-4-5-6-7-8
0-1-2-3-4-5-6-8-7
0-1-2-3-4-5-8-6-7
0-1-2-3-4-8-5-6-7
0-1-2-3-8-4-5-6-7
0-1-2-8-3-4-5-6-7
and so on...
You're looking for the permutations formula:
nPk = n!/(n-k)!
In your case, you have 9 entries and you want to choose all of them, that's 9P9 = 9! = 362880
You can find a PHP algorithm to permutate in recipe 4.26 of O'Reilly's "PHP Cookbook".
pc_permute(array(0, 1, 2, 3, 4, 5, 7, 8));
Copied in from O'Reilly:
function pc_permute($items, $perms = array( )) {
if (empty($items)) {
print join(' ', $perms) . "\n";
} else {
for ($i = count($items) - 1; $i >= 0; --$i) {
$newitems = $items;
$newperms = $perms;
list($foo) = array_splice($newitems, $i, 1);
array_unshift($newperms, $foo);
pc_permute($newitems, $newperms);
}
}
}
Since PHP 5.5 you can use Generators. Generators save a lot of memory and are way faster (more than half compared to pc_permute()). So if you have any chance of having PHP 5.5 installed, you definitely want Generators.
This snipped is ported from Python: https://stackoverflow.com/a/104436/3745311
function permutations(array $elements)
{
if (count($elements) <= 1) {
yield $elements;
} else {
foreach (permutations(array_slice($elements, 1)) as $permutation) {
foreach (range(0, count($elements) - 1) as $i) {
yield array_merge(
array_slice($permutation, 0, $i),
[$elements[0]],
array_slice($permutation, $i)
);
}
}
}
}
Sample usage:
$list = ['a', 'b', 'c'];
foreach (permutations($list) as $permutation) {
echo implode(',', $permutation) . PHP_EOL;
}
Output:
a,b,c
b,a,c
b,c,a
a,c,b
c,a,b
c,b,a
Since this question often comes up in Google Search results, here's a modified version of the accepted answer that returns all combinations in an array and passes them as a return value of the function.
function pc_permute($items, $perms = array( )) {
if (empty($items)) {
$return = array($perms);
} else {
$return = array();
for ($i = count($items) - 1; $i >= 0; --$i) {
$newitems = $items;
$newperms = $perms;
list($foo) = array_splice($newitems, $i, 1);
array_unshift($newperms, $foo);
$return = array_merge($return, pc_permute($newitems, $newperms));
}
}
return $return;
}
To use:
$value = array('1', '2', '3');
print_r(pc_permute($value));
I've something that You may like
function combination_number($k,$n){
$n = intval($n);
$k = intval($k);
if ($k > $n){
return 0;
} elseif ($n == $k) {
return 1;
} else {
if ($k >= $n - $k){
$l = $k+1;
for ($i = $l+1 ; $i <= $n ; $i++)
$l *= $i;
$m = 1;
for ($i = 2 ; $i <= $n-$k ; $i++)
$m *= $i;
} else {
$l = ($n-$k) + 1;
for ($i = $l+1 ; $i <= $n ; $i++)
$l *= $i;
$m = 1;
for ($i = 2 ; $i <= $k ; $i++)
$m *= $i;
}
}
return $l/$m;
}
function array_combination($le, $set){
$lk = combination_number($le, count($set));
$ret = array_fill(0, $lk, array_fill(0, $le, '') );
$temp = array();
for ($i = 0 ; $i < $le ; $i++)
$temp[$i] = $i;
$ret[0] = $temp;
for ($i = 1 ; $i < $lk ; $i++){
if ($temp[$le-1] != count($set)-1){
$temp[$le-1]++;
} else {
$od = -1;
for ($j = $le-2 ; $j >= 0 ; $j--)
if ($temp[$j]+1 != $temp[$j+1]){
$od = $j;
break;
}
if ($od == -1)
break;
$temp[$od]++;
for ($j = $od+1 ; $j < $le ; $j++)
$temp[$j] = $temp[$od]+$j-$od;
}
$ret[$i] = $temp;
}
for ($i = 0 ; $i < $lk ; $i++)
for ($j = 0 ; $j < $le ; $j++)
$ret[$i][$j] = $set[$ret[$i][$j]];
return $ret;
}
Here is how to use it:
To get the number of combinations:
combination_number(3,10); // returns number of combinations of ten-elements set.
To get all possible combinations:
$mySet = array("A","B","C","D","E","F");
array_combination(3, $mySet); // returns all possible combinations of 3 elements of six-elements set.
Hope You make use of that.
I've ported the Python itertools code listed here (using generators). The advantage over the solutions posted so far is that it allows you to specify r (permutation size).
function permutations($pool, $r = null) {
$n = count($pool);
if ($r == null) {
$r = $n;
}
if ($r > $n) {
return;
}
$indices = range(0, $n - 1);
$cycles = range($n, $n - $r + 1, -1); // count down
yield array_slice($pool, 0, $r);
if ($n <= 0) {
return;
}
while (true) {
$exit_early = false;
for ($i = $r;$i--;$i >= 0) {
$cycles[$i]-= 1;
if ($cycles[$i] == 0) {
// Push whatever is at index $i to the end, move everything back
if ($i < count($indices)) {
$removed = array_splice($indices, $i, 1);
array_push($indices, $removed[0]);
}
$cycles[$i] = $n - $i;
} else {
$j = $cycles[$i];
// Swap indices $i & -$j.
$i_val = $indices[$i];
$neg_j_val = $indices[count($indices) - $j];
$indices[$i] = $neg_j_val;
$indices[count($indices) - $j] = $i_val;
$result = [];
$counter = 0;
foreach ($indices as $indx) {
array_push($result, $pool[$indx]);
$counter++;
if ($counter == $r) break;
}
yield $result;
$exit_early = true;
break;
}
}
if (!$exit_early) {
break; // Outer while loop
}
}
}
It works for me, but no promises!
Example usage:
$result = iterator_to_array(permutations([1, 2, 3, 4], 3));
foreach ($result as $row) {
print implode(", ", $row) . "\n";
}
This is my version of class. This class builds and returns permutated array as result
class Permutation {
private $result;
public function getResult() {
return $this->result;
}
public function permute($source, $permutated=array()) {
if (empty($permutated)){
$this->result = array();
}
if (empty($source)){
$this->result[] = $permutated;
} else {
for($i=0; $i<count($source); $i++){
$new_permutated = $permutated;
$new_permutated[] = $source[$i];
$new_source = array_merge(array_slice($source,0,$i),array_slice($source,$i+1));
$this->permute($new_source, $new_permutated);
}
}
return $this;
}
}
$arr = array(1,2,3,4,5);
$p = new Permutation();
print_r($p->permute($arr)->getResult());
The last three lines to test my class.
This is a simple recursive function that prints all permutations (written in pseudocode)
function rec(n, k) {
if (k == n) {
for i = 0 to n-1
print(perm[i], ' ');
print('\n');
}
else {
for i = 0 to n-1 {
if (not used[i]) {
used[i] = true;
perm[k] = i;
rec(n, k+1);
used[i] = false;
}
}
}
}
And it is called like this:
rec(9, 0);
Lexicographical order. There is no recursion. Almost no limits for array length.
There is no sort. It's running rather fast. It's easy to understand.
Minus: it gives a notice, but you can add a condition to start compare with the second element or error_reporting(0).
$a = array(
1,
2,
3,
4,
5
);
$b = array_reverse($a);
print_r($a);
//here need "br"
while ($a != $b)
{
foreach(array_reverse($a, true) as $k => $v)
{
if ($v < $a[$k + 1])
{
foreach(array_reverse($a, true) as $ka => $val)
{
if ($val > $v) break;
}
$ch = $a[$k];
$a[$k] = $a[$ka];
$a[$ka] = $ch;
$c = array_slice($a, 0, $k + 1);
print_r($a = array_merge($c, array_reverse(array_slice($a, $k + 1))));
//here need "br"
break;
}
}
}
You're basically talking about permutations where both n and k are 9 so you'll have 9! different permutations; see this: http://en.wikipedia.org/wiki/Permutation.
Here is my proposal, hope a little bit clearer than accepted answer.
function permutate($elements, $perm = array(), &$permArray = array())
{
if(empty($elements))
{
array_push($permArray,$perm); return;
}
for($i=0;$i<=count($elements)-1;$i++)
{
array_push($perm,$elements[$i]);
$tmp = $elements; array_splice($tmp,$i,1);
permutate($tmp,$perm,$permArray);
array_pop($perm);
}
return $permArray;
}
and usage:
$p = permutate(array('a','b','c'));
foreach($p as $perm)
print join(",",$perm)."|\n";
//function call
print_r(combinations([1,2,3,4,5,6,7,8,9,10,11,12,13]));
/**
* #param $mainArray
* #param int $size - optional
* #param array $combinations - optional
* #return mixed
*/
function combinations($mainArray, $size = 3, $combinations = [])
{
if (empty($combinations)) {
$combinations = $mainArray;
}
if ($size == 1) {
return str_replace('-','',$combinations);;
}
$newCombination = array();
foreach ($mainArray as $key => $val){
foreach ($combinations as $char) {
if(in_array($val, explode('-', $char))){
continue;
}
$newCombination[] = $val . '-' . $char;
}
}
return combinations($mainArray, $size - 1, $newCombination);
}
//========================= Next solution ==================================
function sampling($chars, $size, $combinations = array()) {
# if it's the first iteration, the first set
# of combinations is the same as the set of characters
if (empty($combinations)) {
$combinations = $chars;
}
# we're done if we're at size 1
if ($size == 1) {
return $combinations;
}
# initialise array to put new values in
$new_combinations = array();
# loop through existing combinations and character set to create strings
foreach ($combinations as $combination) {
foreach ($chars as $char) {
$new_combinations[] = $combination .'-'. $char ;
}
}
# call same function again for the next iteration
return $this->sampling($chars, $size - 1, $new_combinations);
}
function array_has_dupes($array) {
return count($array) !== count(array_unique($array));
}
function total() {
// Generate ticket price
$arrfinal = array();
// combinations
$chars = array(1,2,3,4,5,6,7,8,9,10,11,12,13); // for 10 digits
$combinations = $this->sampling($chars, 3);
//print_r($combinations); //exit;
foreach($combinations as $key => $val)
{
$arr = explode('-', $val);//str_split($val);
if(!$this->array_has_dupes($arr)){
$arrfinal[] = str_replace('-', '', $val);
}
}
echo '<pre>'; print_r($arrfinal); echo '</pre>';
}
Simple solution using recursion
function filterElement($element){
if(is_array($element[0])){
return $element[0];
}
# base case
return $element;
}
function permutation($input, $path){
// base case 1
if(count($input) == 0){
return [$path];
}
$output = [];
foreach($input as $index => $num){ # 1, 2,3, 4
$copyPath = $path; # copy the path - []
$copyPath[] = $num; # append the number [1]
# remove the current number
$inputLocal = $input;
unset($inputLocal[$index]); # [2, 3, 4]
$permute = permutation($inputLocal, $copyPath); # call [2, 3, 4], [1]
# for all element find add to output
foreach($permute as $ele){
# filter ouput
$output[] = filterElement($ele);
}
}
return $output;
}
print_r(permutation([1,2,3,4], []));
output
Array
(
[0] => Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
)
[1] => Array
(
[0] => 1
[1] => 2
[2] => 4
[3] => 3
)
[2] => Array
(
[0] => 1
[1] => 3
[2] => 2
[3] => 4
)
[3] => Array
(
[0] => 1
[1] => 3
[2] => 4
[3] => 2
)
[4] => Array
(
[0] => 1
[1] => 4
[2] => 2
[3] => 3
)
[5] => Array
(
[0] => 1
[1] => 4
[2] => 3
[3] => 2
)
[6] => Array
(
[0] => 2
[1] => 1
[2] => 3
[3] => 4
)
[7] => Array
(
[0] => 2
[1] => 1
[2] => 4
[3] => 3
)
[8] => Array
(
[0] => 2
[1] => 3
[2] => 1
[3] => 4
)
[9] => Array
(
[0] => 2
[1] => 3
[2] => 4
[3] => 1
)
[10] => Array
(
[0] => 2
[1] => 4
[2] => 1
[3] => 3
)
[11] => Array
(
[0] => 2
[1] => 4
[2] => 3
[3] => 1
)
[12] => Array
(
[0] => 3
[1] => 1
[2] => 2
[3] => 4
)
[13] => Array
(
[0] => 3
[1] => 1
[2] => 4
[3] => 2
)
[14] => Array
(
[0] => 3
[1] => 2
[2] => 1
[3] => 4
)
[15] => Array
(
[0] => 3
[1] => 2
[2] => 4
[3] => 1
)
[16] => Array
(
[0] => 3
[1] => 4
[2] => 1
[3] => 2
)
[17] => Array
(
[0] => 3
[1] => 4
[2] => 2
[3] => 1
)
[18] => Array
(
[0] => 4
[1] => 1
[2] => 2
[3] => 3
)
[19] => Array
(
[0] => 4
[1] => 1
[2] => 3
[3] => 2
)
[20] => Array
(
[0] => 4
[1] => 2
[2] => 1
[3] => 3
)
[21] => Array
(
[0] => 4
[1] => 2
[2] => 3
[3] => 1
)
[22] => Array
(
[0] => 4
[1] => 3
[2] => 1
[3] => 2
)
[23] => Array
(
[0] => 4
[1] => 3
[2] => 2
[3] => 1
)
)
I want to create an array which has two columns. The output should contain only the existing letters in the word with their amounts.
The wanted output of the following code
a 3
s 2
p 1
What is wrong in the following PHP code?
<?php
$alpha = array('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','z','y');
$word = "saapas";
for ( $i = 0; $i < count($word); $i++ ) {
echo $word[$i] . "\n";
$table[$word[$i]][]++; // Problem here
}
// array_unique, array_combine and some method which can sort arrays by alphabets can be useful
PHP has extensive array functions that do much of the heavy lifting for this:
$keys = range('a', 'z');
$values = array_fill(0, 26, 0);
$freq = array_combine($keys, $values);
$word = "saapas";
$len = strlen($word);
for ($i=0; $i<$len; $i++) {
$letter = strtolower($word[$i]);
if (array_key_exists($letter, $freq)) {
$freq[$letter]++;
}
}
print_r($freq);
Output:
Array
(
[a] => 3
[b] => 0
[c] => 0
[d] => 0
[e] => 0
[f] => 0
[g] => 0
[h] => 0
[i] => 0
[j] => 0
[k] => 0
[l] => 0
[m] => 0
[n] => 0
[o] => 0
[p] => 1
[q] => 0
[r] => 0
[s] => 2
[t] => 0
[u] => 0
[v] => 0
[w] => 0
[x] => 0
[y] => 0
[z] => 0
)
If you want to distinguish between uppercase and lowercase try:
$keys = array_merge(range('a', 'z'), range('A', 'Z'));
$values = array_fill(0, 52, 0);
$freq = array_combine($keys, $values);
$word = "saApas";
$len = strlen($word);
for ($i=0; $i<$len; $i++) {
$letter = $word[$i];
if (array_key_exists($letter, $freq)) {
$freq[$letter]++;
}
}
print_r($freq);
Or to count any characters:
$freq = array();
$word = "saApas";
$len = strlen($word);
for ($i=0; $i<$len; $i++) {
$letter = $word[$i];
if (array_key_exists($letter, $freq)) {
$freq[$letter]++;
} else {
$freq[$letter] = 1;
}
}
print_r($freq);
This works using your input characters array, but do you really want to build a static array for this task?
$table = array();
$count = strlen($word);
for ( $i = 0; $i < $count; $i++ ) {
$letter = $word[$i];
if ( !isset($table[$letter]) )
{
$table[$letter] = 0;
}
++$table[$letter];
}
Here's a method of doing the same thing, but utilizing PHP's native functions:
$ascii = count_chars($word, 1);
$keys = array_keys($ascii);
$chars = array_map('chr', $keys);
$charCount = array_values($ascii);
$table = array_combine($chars, $charCount);
Why complicate?
$string = 'the grey fox jumps over the lazy dog';
$words = explode(' ', $string);
foreach ($words as $key => $value)
{
$words[$key] = count_chars($value, 1);
}
echo '<pre>';
print_r($words);
echo '</pre>';
for ( $i = 0; $i < $alpha.length; $i++ ) {
$count = 0;
for($a = 0; $a < count($word); $a++)
{
if($word[$a] == $array[$i]
$count++;
}
if($count > 0)
echo $array[$i] . " " . $count . "\n";
}
So we use 2 for loops. A little inefficient that what your trying to do. One to check for each character of the alphabet. The second loop is to loop through the string and count the matches against the alphabet the first loop is on.
Edit:
Or you could add a zero to the line below and remove the echo from the loop. Which still requires another loop to display this table.
$table[$word[$i]][0]++;
try this out.it is a single iteration method and faster and simple!
<?php
$word = "saapas";
$result;
for ( $i = 0; $i < strlen($word); $i++ ) {
echo $word[$i] . "\n";
$result[$word[$i]]++; //make use of associative arrays to store the count for each alphabet.
}
foreach($result as $key => $value)//print each element inside the result array
{
print $key . " = " . $value . "<br />";
}
?>
count() doesn't quite work that way, you have to explicitly convert to an array if you want to use the count function. As for the $table array, you have an extra dimension (the []).
The following code should work (it is not optimal but should get you pointed in the right direction.)
$word = str_split("saapas");
for ( $i = 0; $i < count($word); $i++ ) {
$table[$word[$i]]++;
}
foreach ($table as $key => $value) {
print "$key $value\n";
}