drupol\phpartition\Algorithm\BruteForceCustomA::getResult()

Complexity

Conditions	5
Paths	8

Size

Total Lines	53
Code Lines	25

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	29
CRAP Score	5

Importance

Changes

0

<?php
    public function getResult()
    {
        // Sort the initial data set ascending.
        $this->getDataPartition()->sortByValue('ASC');
        // Compute the maximum value of the variance.
        $variance = pow(2, $this->getDataPartition()->size());
        // Set a default value for the variable that will contain the solution.
        $solution = null;
        // Get the number of elements in the input dataset.
        $count = $this->getDataPartition()->size();
        // Compute the size of a chunk. Ceiling the value because it cannot be zero.
        $chunkSize = ceil($count / $this->getSize());
        // Get the rest of the division of the element count by the number of
        // partitions.
        $rest = $count % $this->getSize();

        $permutations = new Permutations($this->getDataPartition()->toArray());

        // Loop through each permutation and
        // compute the variance of each subsetchunks.
        $i = 0;
        foreach ($permutations->generator() as $subset) {
            $i++;
            // Get the variance of the sums array.
            $varianceCandidate = Statistics::variance(
                array_map(function ($items) {
                    $partition = new Partition();
                    $partition->addItems($items);
                    return $partition->getWeight();
                }, array_chunk($subset, $chunkSize))
            );

            // If we've found a better variance with this subset, store it.
            if ($varianceCandidate < $variance) {
                  $variance = $varianceCandidate;
                  $solution = $subset;

                  // If the variance is equal to the size of the set module the number of
                  // partition that we want, that means that's the best candidate,
                  // store the value and exit the loop prematurely.
                if ($rest == $varianceCandidate) {
                    break;
                }
            }
        }

        // Store each chunks into a subset in the SubsetContainer.
        foreach (array_chunk($solution, $chunkSize) as $subsetChunks) {
            $this->getPartitionContainer()->insert($this->getPartition()->addItems($subsetChunks));
        }

        return $this->getPartitionContainer()->getPartitionsItemsArray();
    }
}