I'm trying to combine numbers in an array by adding them so that the max value can only by 30.
For example, this is my array:
array(10,30,10,10,15);
After combining the numbers in the array to items with a max value 30, the result should be:
array(30,30,15);
How to achieve this?
I'm trying to combine numbers in an array by adding them so that the
max value can only by 30
So, when you combine numbers, you can achieve the lowest possible set of values in your array and also make sure that max value remains 30 by:
First, sort them.
Second, keeping adding elements to sum till you are about to get a sum > 30.
Third, once an element can no longer be added to a sum, add the current sum in your array and make the current element as the new sum.
Code:
<?php
$arr = array(10,30,10,10,15);
sort($arr);
$res = [];
$curr_sum = 0;
foreach($arr as $each_value){
if($curr_sum + $each_value <= 30) $curr_sum += $each_value;
else{
$res[] = $curr_sum;
$curr_sum = $each_value;
}
}
$res[] = $curr_sum;
print_r($res);
Demo: https://3v4l.org/BYhuE
Update: If order of the numbers matters, seeing your current output, you could just use rsort() to show them in descending order.
rsort($res);
$total = array_sum(array(10,30,10,10,15)); //assign sum totals from orignal array
$maxValue = 30; //assign max value allowed in array
$numberOfWholeOccurancesOfMaxValue = floor($total/$maxValue);
$remainder = $total%$maxValue;
//build array
$i=0;
while ( $i < $numberOfWholeOccurancesOfMaxValue ){
$array[] = $maxValue;
$i++;
}
$array[] = $remainder;
print_r($array);
You can loop only once to get this,
$temp = array(10,30,10,10,15);
natsort($temp); // sorting to reduce hustle and complication
$result = [];
$i = 0;
$maxValue = 30;
foreach($temp as $v){
// checking sum is greater or value is greater or $v is greater than equal to
if(!empty($result[$i]) && (($result[$i]+$v) > $maxValue)){
$i++;
}
$result[$i] = (!empty($result[$i]) ? ($result[$i]+$v) : $v);
}
print_r($result);
Working demo.
I believe finding most space-optimized/compact result requires a nested loop. My advice resembles the firstFitDecreasing() function in this answer of mine except in this case the nested loops are accessing the same array. I've added a couple of simple conditions to prevent needless iterations.
rsort($array);
foreach ($array as $k1 => &$v1) {
if ($v1 >= $limit) {
continue;
}
foreach ($array as $k2 => $v2) {
if ($k1 !== $k2 && $v1 + $v2 <= $limit) {
$v1 += $v2;
unset($array[$k2]);
if ($v1 === $limit) {
continue 2;
}
}
}
}
rsort($array);
var_export($array);
By putting larger numbers before smaller numbers before processing AND by attempting to add multiple subsequent values to earlier values, having fewer total elements in the result is possible.
See my comparative demonstration.
I believe #Clint's answer is misinterpreting the task and is damaging the data by summing all values then distributing the max amounts in the result array.
With more challenging input data like $array = [10,30,5,10,5,13,14,15,10,5]; and $limit = 30;, my solution provides a more dense result versus #nice_dev's and #rahul's answers.
Sorry for the title as it looks like most of the other questions about combining arrays, but I don't know how to write it more specific.
I need a PHP function, which combines the entries of one array (dynamic size from 1 to any) to strings in every possible combination.
Here is an example with 4 entries:
$input = array('e1','e2','e3','e4);
This should be the result:
$result = array(
0 => 'e1',
1 => 'e1-e2',
2 => 'e1-e2-e3',
3 => 'e1-e2-e3-e4',
4 => 'e1-e2-e4',
5 => 'e1-e3',
6 => 'e1-e3-e4',
7 => 'e1-e4'
8 => 'e2',
9 => 'e2-e3',
10 => 'e2-e3-e4',
11 => 'e2-e4',
12 => 'e3',
13 => 'e3-e4',
14 => 'e4'
);
The sorting of the input array is relevant as it affects the output.
And as you see, there should be an result like e1-e2 but no e2-e1.
It seems really complicated, as the input array could have any count of entries.
I don't even know if there is a mathematical construct or a name which describes such a case.
Has anybody done this before?
You are saying that there might be any number of entries in the array so I'm assuming that you aren't manually inserting the data and there would be some source or code entering the data. Can you describe that? It might be easier to directly store it as per your requirement than having an array and then changing it as per your requirement
This might be helpful Finding the subsets of an array in PHP
I have managed to bodge together a code that creates the output you want from the input you have.
I think I have understood the logic of when and why each item looks the way it deos. But Im not sure, so test it carefully before using it live.
I have a hard time explaining the code since it's really a bodge.
But I use array_slice to grab the values needed in the strings, and implode to add the - between the values.
$in = array('e1','e2','e3','e4');
//$new =[];
$count = count($in);
Foreach($in as $key => $val){
$new[] = $val; // add first value
// loop through in to greate the long incrementing string
For($i=$key; $i<=$count-$key;$i++){
if($key != 0){
$new[] = implode("-",array_slice($in,$key,$i));
}else{
if($i - $key>1) $new[] = implode("-",array_slice($in,$key,$i));
}
}
// all but second to last except if iteration has come to far
if($count-2-$key >1) $new[] = Implode("-",Array_slice($in,$key,$count-2)). "-". $in[$count-1];
// $key (skip one) next one. except if iteration has come to far
If($count-2-$key >1) $new[] = $in[$key] . "-" . $in[$key+2];
// $key (skip one) rest of array except if iteration has come to far
if($count-2-$key > 1) $new[] = $in[$key] ."-". Implode("-",Array_slice($in,$key+2));
// $key and last item, except if iteration has come to far
if($count-1 - $key >1) $new[] = $in[$key] ."-". $in[$count-1];
}
$new = array_unique($new); // remove any duplicates that may have been created
https://3v4l.org/uEfh6
here is a modificated version of Finding the subsets of an array in PHP
function powerSet($in,$minLength = 1) {
$count = count($in);
$keys = array_keys($in);
$members = pow(2,$count);
$combinations = array();
for ($i = 0; $i < $members; $i++) {
$b = sprintf("%0".$count."b",$i);
$out = array();
for ($j = 0; $j < $count; $j++) {
if ($b{$j} == '1') {
$out[] = $keys[$j];
}
}
if (count($out) >= $minLength) {
$combinations[] = $out;
}
}
$result = array();
foreach ($combinations as $combination) {
$values = array();
foreach ($combination as $key) {
$values[$key] = $in[$key];
}
$result[] = implode('-', $values);
}
sort($result);
return $result;
}
This seems to work.
Say i have:
$array = (1,1,1,1,2,2,2,2,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0);
What I'm trying to achive is to reorder elements evenly in it.
PHP's function shuffle() don't fits here, because i want some distance between same digits. So 1's has to be somewhere in the beginning of array, in the middle and in the end too.
I google about Fisher-Yates_shuffle algorithm, but it seems to work exactly like shuffle().
Thanks in advance!
I think this is close to what you ask: A constant, reasonably even distribution of the items in an array.
// The input array. 0s are regarded as blanks.
$array = array(1,1,1,1,2,2,2,2,3,3,3,3,3,3,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0);
// Count the times each item occurs. PHP will probably have a function for that, but I don't know.
$counter = array();
foreach ($array as $item)
{
// Zeros are infill. Don't process them now, only process the other numbers and
// the zeros will occupy the remaining space.
if ($item === 0)
continue;
if (!array_key_exists($item, $counter))
$counter[$item] = 0;
$counter[$item]++;
}
// Reverse sort by quantity. This results in the best distribution.
arsort($counter);
// Pre-fill a new array with zeros.
$resultCount = count($array);
$result = array_fill(0, $resultCount, 0);
// Distribute the items in the array, depending on the number of times they occur.
foreach ($counter as $item => $count)
{
// Determine the division for this item, based on its count.
$step = $resultCount / $count;
// Add the item the right number of times.
for ($i = 0; $i < $count; $i++)
{
// Start with the index closest to the preferred one (based on the calculated step).
$index = 0;
$startIndex = (int)($step * $i);
// Count up until a right index is found.
for ($index = $startIndex; $index < $resultCount; $index++)
{
if ($result[$index] === 0)
{
$result[$index] = $item;
break;
}
}
// If no proper index was found, count fown from the starting index.
if ($index === $resultCount)
{
for ($index = $startIndex; $index >= 0; $index--)
{
if ($result[$index] === 0)
{
$result[$index] = $item;
break;
}
}
}
// Still no proper index found, that shouldn't be possible. There's always room.
if ($index === -1)
{
throw new Exception('This cannot not happen');
}
}
}
var_dump($result);
For array:
1,1,1,1,2,2,2,2,3,3,3,3,3,3,3,3,3,3,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
It returns:
3,2,1,0,3,0,0,0,3,0,2,1,3,0,0,0,3,0,0,0,0,3,2,1,0,3,0,0,0,3,0,2,1,3,0,0,0,3,0,0,0,0
For array:
1,1,1,1,2,2,2,2,3,3,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,0,0
It returns:
4,4,3,4,3,4,2,4,3,4,2,4,3,4,1,4,3,4,1,4,0,4,4,3,4,3,4,2,4,3,4,2,4,3,4,1,4,3,4,1,4,0
Which I think is a neat distribution. Thanks to datdo for the idea of sorting the intermediate array.
I have a array with the lvl=>xp correspondance and I would make a function that return the lvl for a specific xp. like $lvl = getLvlOf(15084); //return 5
$lvl_correspondance = array(
1=>100,
2=>520,
3=>2650,
4=>6588,
5=>12061,
6=>23542,
...
n=>xxxxxx
);
I search the easyest and ressourceless way to do it.
Sorry for my poor english :(
Assuming the level values in the array are kept sorted, e.g. (it's 100,200,300, 400, etc... and not 200,500,100,300,400), then a simple scan will do the trick:
$xp = 15084;
$last_key = null;
foreach($lvl_correspondenance as $key => $val) {
if ($val < $xp) {
$last_key = $key;
} else {
break;
}
}
That'll iterate through the array, and jump out as soon as the XP level in the array is larger than the XP level you're looking for, leaving the key of that "last" level in $last_key
function getLvlOf($lvl, $int){
foreach($lvl as $level=>$exp){
if($exp > $int){
return $level-1;
}
}
}
it's O(n) so no magic there...
It looks like your array can be computed live -
XP = exp( 3 * ln(LVL) + 4 ) * 2
You can do the same in reverse, in O(1):
LVL = exp(ln(XP/2) - 4 / 3)
I rounded the equation, so there may be a +/- 1 issue
Good Luck!
Not good if you have very high level values, but:
$lvl = $lvl_correspondance[array_search(
max(array_intersect(
array_values($lvl_correspondance),
range(0,$points)
)
),
$lvl_correspondance
)];
You can use array_flip if the xp levels are distinct. Then you can simply access the level number using the xp as index:
$levels = array_flip($lvl_correspondance);
$lvl = $levels[15084];
EDIT: But maybe a function would be better to fetch even the xp levels in between:
function getLvlOf($xp) {
// get the levels in descending order
$levels = array_reverse($GLOBALS['lvl_correspondance'], true);
foreach ($levels as $key => $value) {
if ($xp >= $value)
return $key;
}
// no level reached yet
return 0;
}