PHP List All Combination of Elements of Array - php

I have an array:
$arr=array("A","B","C");
I want to make its all of combination as:
array("A")
array("B")
array("C")
array("A","B")
array("A","C")
array("B","C")
array("A","B","C")
i want to make an process all of this combinations but i don't want generate all combinations, store them in an array and apply function to them. Because this requires a lot of memory with large combinations. I have 40 items for this process (I have long time but i don't have enough memory).
I want to have a function like this:
function ProcessArrayCombinations($array){
foreach($array as $v){
//generate and process next combination of array
print_r($nextcombination);
}
}
Thank you.

This code recognizes the combinations as binary numbers, using the fact that there is a formula which states that the sum of all combinations possible from n elements is 2^n. Knowing its binary logarithm is integer, we can define a model where each possible binary number constructed from n digits is a set of combinations. Code is untested, if there are typos, please, let me know in comments.
function ProcessArrayCombinations($array) {
$status = array();
foreach ($array as $element) {
$status[] = false;
}
$elementCount = count($status);
$trues = 0;
while ($trues < $elementCount) {
$index = 0;
$stop = false;
while ((!$stop) && ($index < count($status)) && ($status[$index])) {
$status[$index] = false;
$trues--;
$index++;
}
$status[$index] = true;
$trues++;
//Found a new combination
//We should print elements from $array located at indexes fulfilling
//the criteria that the element having the same index in $status is true:
//for ($i = 0; $i < count($status); $i++) {
// if ($status[$i}) {
// print
// } else {
// don't print
// }
//}
}
}

I edited and used your function as below. Thank you again Lajos.
function ProcessArrayCombinations($array) {
$status = array();
foreach ($array as $element) {
$status[] = false;
}
$elementCount = count($status);
$trues = 0;
while ($trues < $elementCount) {
$index = 0;
$stop = false;
while ((!$stop) && ($index < count($status)) && ($status[$index])) {
$status[$index] = false;
$trues--;
$index++;
}
$status[$index] = true;
$trues++;
//Found a new combination
//We should print elements from $array located at indexes fulfilling
//the criteria that the element having the same index in $status is true:
for ($i = 0; $i < count($status); $i++) {
if ($status[$i]) {
echo $array[$i];
}
}
echo '<br/>';
}
}

Related

PHP: Transform string to another string

I would like to Convert simple string to another format based on below logic
Example 1 : if string is 3,4-8-7,5 then I need the set as (3,8,7),(4,8,5).
Example 2: If string is "4-5,6-4" then required set will be (4,5,4),(4,6,4).
More Clear Requirements:
if string is 5-6,7,8-2,3-1. It need to be divided first like [5] AND [(6) OR (7) OR (8)] AND [(2) OR (3)] AND [1]. Result must be All possible combination: (5,6,2,1),(5,6,3,1),(5,7,2,1),(5,7,3,1),(5,8,2,1),(5,8,3,1).
The Logic behind to building the set are we need to consider ',' as OR condition and '-' as AND condition.
I am trying my best using For loop but unable to find solution
$intermediate = array();
$arry_A = explode('-', '3,4-8-7,5');
for ($i = 0; $i < count($arry_A); $i++) {
$arry_B = explode(',', $arry_A[$i]);
for ($j = 0; $j < count($arry_B); $j++) {
if (count($intermediate) > 0) {
for ($k = 0; $k < count($intermediate); $k++) {
$intermediate[$k] = $intermediate[$k] . ',' . $arry_B[$j];
}
} elseif (count($intermediate) === 0) {
$intermediate[0] = $arry_B[$j];
}
}
}
echo $intermediate, should give final result.
Cool little exercise!
I would do it with the following code, which I will split up for readability:
I used an array as output, since it's easier to check than a string.
First, we initialize the $string and create the output array $solutions. We will calculate the maximum of possible combinations from the beginning ($results) and fill the $solutions array with empty arrays which will be filled later with the actual combinations.
$string = '3,4-8-7,5';
$solutions = array();
$results = substr_count($string,',')*2;
for($i = 0; $i < $results; $i++) {
array_push($solutions,array());
}
We will need two helper functions: checkSolutions which makes sure, that the combination does not yet exist more than $limit times. And numberOfORAfterwards which will calculate the position of an OR pattern in the $string so we can calculate how often a combination is allowed in the single steps of the walkthrough.
function checkSolutions($array,$solutions,$limit) {
$count = 0;
foreach($solutions as $solution) {
if($solution === $array) $count++;
}
if($count < $limit) return true;
else return false;
}
function numberOfORAfterwards($part,$parts) {
foreach($parts as $currPart) {
if($currPart === $part) $count = 0;
if(isset($count)) if(!ctype_digit($currPart)) $count++;
}
return $count;
}
Now the main part: We are going to loop over the "parts" of the $string a part are the digits between AND operations.
If you need further explanation on this loop, just leave a comment.
$length = 0;
// split by all AND operations
$parts = explode('-',$string);
foreach($parts as $part) {
if(ctype_digit($part)) {
// case AND x AND
foreach($solutions as &$solution) {
array_push($solution,$part);
}
} else {
// case x OR x ...
$digits = explode(',',$part);
foreach($digits as $digit) {
for($i = 0; $i < $results/count($digits); $i++) {
foreach($solutions as &$solution) {
if(count($solution) == $length) {
$test = $solution;
array_push($test,$digit);
$limit = numberOfORAfterwards($part,$parts);
echo $digit.' '.$limit.'<br>';
if(checkSolutions($test,$solutions,$limit)) {
array_push($solution,$digit);
break;
}
}
}
}
}
}
$length++;
}
print_r($solutions);
Some tests:
String: 3,4-8-7,5
Combinations: (3,8,7)(3,8,5)(4,8,7)(4,8,7)
String: 5-6,7,8-2,3-1
Combinations: (5,6,2,1)(5,6,3,1)(5,7,2,1)(5,7,3,1)(5,8,2,1)(5,8,2,1)
String: 2,1-4-3,2-7,8-9
Combinations: (2,4,3,7,9)(2,4,3,8,9)(2,4,2,7,9)(1,4,3,7,9)(1,4,2,8,9)(1,4,2,8,9)
String: 1,5-3,2-1
Combinations: (1,3,1)(1,2,1)(5,3,1)(5,3,1)

PHP Radix Sort Algorithm - Type conversion ok?

This is a function I wrote for a Radix Sort in PHP.
It works for all cases where the array is populated with numbers greater than 0.
function radix_sort($arr) {
// Find the number of passes needed to complete the sort
$passes = strlen((string)max($arr));
$buckets = [];
// Start the passes
for($i = 1; $i <= $passes; $i++) {
// Create - reinitialize some buckets
for ($b = 0; $b <= 9; $b++) {
$buckets[$b] = [];
}
for ($j = 0; $j < count($arr); $j++) {
// Drop into the proper bucket based on the significant digit
$numStr = (string)$arr[$j];
if (strlen($numStr) < $i) {
$bucketsIndex = 0;
} else {
$bucketsIndex = $numStr[strlen($numStr) - $i];
}
array_push($buckets[$bucketsIndex], $arr[$j]);
}
// Repopulate our array by pulling out of our buckets
$k = 0;
foreach ($buckets as $bucket) {
foreach ($bucket as $value) {
$arr[$k] = $value;
$k++;
}
}
}
return $arr;
}
I feel like there's too much type converting going on. Is it ok to be doing this? If I wanted to pull the Nth digit from a large number, is there a better way in PHP?
You could convert all the value to string before the function, and then revert back to int at the end:
function radix_sort($arr) {
$arr = array_map ('strval', $arr) ;
$passes = strlen(max($arr)) ; // Should still work since all values are numeric
/* Do your stuff... */
return array_map ('intval', $arr) ;
}
Then in your inner loop you could store the length (I don't really know the complexity of strlen in PHP but I assumed it is not O(1)):
for ($j = 0; $j < count($arr); $j++) {
// Drop into the proper bucket based on the significant digit
$numStr = $arr[$j];
$numLen = strlen($numStr) ;
if ($numLen < $i) {
$bucketsIndex = 0;
} else {
$bucketsIndex = $numStr[$numLen - $i];
}
array_push($buckets[$bucketsIndex], $arr[$j]);
}
Or you could even (if you have enough memory) use an array to precompute the length:
$lengths = array_map ('strlen', $arr) ;

Issue with custom script to sort Arrays ascending and descending order

I have an issue to deal with here (a logical error in my code 99%). I just can't seem to find the way to fix it, but I bet one of you will find the problem in no time!
I have to create a function which sorts array passed to it in asc or desc order, but can't use any array sorting functions !
I've been struggling with loops until now and I finally want to ask help from other devs ( you ).
Currently only code for ascending is worked on, descending will be no problem I assume once I do this one. It kinda of does sort values up to some point, but then stops ( it stops if the next smallest value is at the end of the passed array ). What could I do to prevent this and make it sort the whole array and it's elements?
Here is the code so far.
<?php
function order_array($array,$mode = 'ascending') {
$length = count($array);
if($mode == 'descending') {
return $array;
} else {
$sorted_array = array();
$used_indexes = array();
for($i = 0; $i < $length; $i++) {
$smallest = true;
echo $array[$i] . '<br/>';
for($y = 0; $y < $length; $y++) {
//echo $array[$i] . ' > ' . $array[$y] . '<br/>';
// if at ANY time during checking element vs other ones in his array, he is BIGGER than that element
// set smallest to false
if(!in_array($y,$used_indexes)) {
if($array[$i] > $array[$y]) {
$smallest = false;
break;
}
}
}
if($smallest) {
$sorted_array[] = $array[$i];
$used_indexes[] = $i;
}
}
return $sorted_array;
}
}
$array_to_sort = array(1, 3, 100, 99, 33, 20);
$sorted_array = order_array($array_to_sort);
print_r($sorted_array);
?>
I've solved the issue myself by doing it completely different. Now it sorts correctly all the elements of the passed in array. The logical issue I had was of using for() loop. The for() loop ran only a set ( length of passed array ) number of times, while we need it to loop more than that, because we will need to loop all the way untill we have a new sorted array in ascending order. Here is the code that will work
function order_array($array,$mode = 'ascending') {
if($mode == 'descending') {
// for() wont work here, since it will only loop an array length of times, when we would need it
// to loop more than that.
while(count($array)){
$value = MAX($array);
$key = array_search($value, $array);
if ($key !== false) {
unset($array[$key]);
}
$sorted[] = $value;
}
return $sorted;
} else {
// for() wont work here, since it will only loop an array length of times, when we would need it
// to loop more than that.
while(count($array)){
$value = MIN($array);
$key = array_search($value, $array);
if ($key !== false) {
unset($array[$key]);
}
$sorted[] = $value;
}
return $sorted;
}
}
function order_array($array,$mode = 'ascending') {
$length = count($array);
$sorted_array = array();
$used_indexes = array();
for($i = 0; $i < $length; $i++) {
$smallest = true;
echo $array[$i] . '<br/>';
for($y = 0; $y < $length; $y++) {
//echo $array[$i] . ' > ' . $array[$y] . '<br/>';
// if at ANY time during checking element vs other ones in his array, he is BIGGER than that element
// set smallest to false
if(!in_array($y,$used_indexes)) {
if($array[$i] > $array[$y]) {
$smallest = false;
break;
}
}
}
if($smallest) {
$sorted_array[] = $array[$i];
$used_indexes[] = $i;
}
if($mode == 'descending') {
return array_reverse($sorted_array);
}
return $sorted_array;
}
}

Counting the number of dimensions in an array [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Is there a way to find how how “deep” a PHP array is?
I am trying to write a method to count the number of dimensions of an array. The following gives me a correct count of dimensions
$array = array();
$array[0] = array();
$array[0][0] = 0;
$array[0][1] = array();
$array[0][1][0] = 10;
$array[0][1][1] = 11;
echo '<p>'.\utility\arrayTools\arrayTools::numberOfDimensions($array).'</p>';
//3 Dimensons
The second examples also gives me a correct count of the number of dimensions
$array = array();
$array[0] = array();
$array[0][0] = 0;
$array[0][1] = array();
$array[0][1][0] = 10;
$array[0][1][1] = 11;
$array[1] = 1;
$array[2] = 2;
//3 Dimensions
But the following example gives me too high of a count
$array = array();
$array[0] = array();
$array[0][0] = 0;
$array[0][1] = array();
$array[0][1][0] = 10;
$array[0][1][1] = 11;
$array[1] = 1;
$array[2] = 2;
$array[3] = array();
$array[3][0] = 30;
//Should still be 3 dimensions, but gives me 4
The method I am using is below
//Method
public static function numberOfDimensions($array)
{
if(func_num_args() === 2){
if(is_int(func_get_arg(1))){
$number_of_dimensions = func_get_arg(1);
}else{
throw new Exception('The second argumment must be an interger');
}
}else{
$number_of_dimensions = 0;
}
if(is_array($array) === TRUE){
$number_of_dimensions++;
if(self::isMultiDimensional($array) === TRUE){
foreach($array as $iteration){
$number_of_dimensions = self::numberOfDimensions($iteration,$number_of_dimensions);
}
return $number_of_dimensions;
}else{
return $number_of_dimensions;
}
}else{
return $number_of_dimensions;
}
}
I already know the problem is it is still adding for every multidimensional even though the count may be equal to or less then the number of dimensions. But what I can't figure out is how to get it to find the highest number of dimensions and stop counting
Here is a simpler version of your script
function numberOfDimensions($array) {
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($array));
$d = 0;
foreach ( $it as $v )
$it->getDepth() >= $d and $d = $it->getDepth();
return ++ $d;
}
From another answer here on SO:
function array_depth($array) {
$max_depth = 1;
foreach ($array as $value) {
if (is_array($value)) {
$depth = array_depth($value) + 1;
if ($depth > $max_depth) {
$max_depth = $depth;
}
}
}
return $max_depth;
}
I havn't written any PHP in a very long while, so there may very well be mistakes in my code, excuse me in advance.
function numberOfDimensions($array,$so_far=0){
if !is_array($array){
return 0;
}
$max_dims = 0;
foreach($array as $element){
$element_dims = numberOfDimensions($array);
$max_dims = max($max_dims,$element_dims);
}
return $max_dims +1;
}
This function assumes it is being called with an array as parameter, thus the minimum depths is 1.
It then recursively looks at all child elements, and if the child is deeper than already known, it add the depth of the child to the calculated depth:
function numberOfDimensions($subject) {
// scalar value has depth 0
if(!is_array($subject)) return 0;
// array has min depth of 1
$depth = 1;
foreach ($subject as $element) {
if (is_array($element)) {
// is the sub array deeper than already known?
$sub_depth = numberOfDimensions($element);
if ($sub_depth >= $depth) {
$depth += $sub_depth;
}
}
}
return $depth;
}

Getting an undefined offset in my PHP array while in a foreach

I need some help, even though I think I'm checking for the length of the array and I should be breaking out of the loop, I still get warnings on my [else if ($value....] line. So either I'm missing something crucial or I've been staring at this code segment too long and its obvious. Any insight would be appreciated.
$count = count($filter); //Filter is an array
if ($count > 1 ){
//Compare values and generate a range to choose from
$i = 1;
foreach($filter as $value){
//Break the loop if at the end of the array
if ($i >= $count){
//throw new exception($i .' '.$count);
break;
}
//if the value is smaller then the next procceding value, because they are already in order of presidence,
//add it to our range of potentials.
else if($value < $filter[$i]->value){
array_push($range, key($filter));
}
$i++;
}
}else {
return false;
}
I suspect that there are gaps in your array. Try this:
$filter = array_values($filter); // this will remove any gaps in the array
$count = count($filter);
if ($count <= 1)
return false;
for ($i = 0; $i < $count; $i++)
{
if ($i != $count-1 && $filter[$i]->value < $filter[$i+1]->value)
array_push($range, key($filter));
}
Your array might have non-numeric keys. Then try this:
foreach($filter as $key=>$value)
{
// test for $filter[$key];
}
Or your $filter array doesn't hold objects, then you can't use the -> in
$filter[$key]->value
try this code.... no need of checking count..
$range = array();
$i = 1;
foreach($filter as $value)
{
if(isset($filter[$i]) && $value < $filter[$i]->value)
{
array_push($range, key($filter));
$i++;
}
else
{
break;
}
}

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