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<?php |
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/* |
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Schulze part of the Condorcet PHP Class |
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By Julien Boudry - MIT LICENSE (Please read LICENSE.txt) |
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https://github.com/julien-boudry/Condorcet |
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*/ |
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declare(strict_types=1); |
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namespace Condorcet\Algo\Methods; |
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use Condorcet\Algo\Method; |
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use Condorcet\Algo\MethodInterface; |
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use Condorcet\CondorcetException; |
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use Condorcet\Result; |
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// Schulze is a Condorcet Algorithm | http://en.wikipedia.org/wiki/Schulze_method |
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abstract class Schulze_Core extends Method implements MethodInterface |
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{ |
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// Schulze |
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protected $_StrongestPaths; |
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/////////// PUBLIC /////////// |
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abstract protected function schulzeVariant (int &$i,int &$j); |
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public function getResult () : Result |
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{ |
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// Cache |
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if ( $this->_Result !== null ) : |
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return $this->_Result; |
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endif; |
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////// |
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// Format array |
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$this->prepareStrongestPath(); |
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// Strongest Paths calculation |
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$this->makeStrongestPaths(); |
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// Ranking calculation |
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$this->makeRanking(); |
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// Return |
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return $this->_Result; |
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} |
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// Get the Schulze ranking |
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protected function getStats () : array |
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{ |
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$explicit = []; |
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foreach ($this->_StrongestPaths as $candidate_key => $candidate_value) : |
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$candidate_key = $this->_selfElection->getCandidateId($candidate_key, true); |
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foreach ($candidate_value as $challenger_key => $challenger_value) : |
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$explicit[$candidate_key][$this->_selfElection->getCandidateId($challenger_key, true)] = $challenger_value; |
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endforeach; |
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endforeach; |
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return $explicit; |
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} |
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/////////// COMPUTE /////////// |
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//:: SCHULZE ALGORITHM. ::// |
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// Calculate the strongest Paths for Schulze Method |
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protected function prepareStrongestPath () : void |
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{ |
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$this->_StrongestPaths = []; |
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foreach ( $this->_selfElection->getCandidatesList() as $candidate_key => $candidate_id ) : |
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$this->_StrongestPaths[$candidate_key] = []; |
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// Format array for the strongest path |
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foreach ( $this->_selfElection->getCandidatesList() as $candidate_key_r => $candidate_id_r ) : |
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if ($candidate_key_r != $candidate_key) : |
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$this->_StrongestPaths[$candidate_key][$candidate_key_r] = 0; |
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endif; |
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endforeach; |
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endforeach; |
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} |
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// Calculate the Strongest Paths |
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protected function makeStrongestPaths () : void |
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{ |
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foreach ($this->_selfElection->getCandidatesList() as $i => $i_value) : |
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foreach ($this->_selfElection->getCandidatesList() as $j => $j_value) : |
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if ($i !== $j) : |
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if ( $this->_selfElection->getPairwise(false)[$i]['win'][$j] > $this->_selfElection->getPairwise(false)[$j]['win'][$i] ) : |
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$this->_StrongestPaths[$i][$j] = $this->schulzeVariant($i,$j); |
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else : |
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$this->_StrongestPaths[$i][$j] = 0; |
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endif; |
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endif; |
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endforeach; |
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endforeach; |
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foreach ($this->_selfElection->getCandidatesList() as $i => $i_value) : |
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foreach ($this->_selfElection->getCandidatesList() as $j => $j_value) : |
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if ($i !== $j) : |
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foreach ($this->_selfElection->getCandidatesList() as $k => $k_value) : |
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if ($i !== $k && $j !== $k) : |
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$this->_StrongestPaths[$j][$k] = |
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max( $this->_StrongestPaths[$j][$k], |
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min($this->_StrongestPaths[$j][$i], $this->_StrongestPaths[$i][$k]) ); |
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endif; |
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endforeach; |
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endif; |
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endforeach; |
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endforeach; |
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} |
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// Calculate && Format human readable ranking |
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protected function makeRanking () : void |
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{ |
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$result = []; |
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// Calculate ranking |
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$done = array (); |
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$rank = 1; |
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while (count($done) < $this->_selfElection->countCandidates()) : |
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$to_done = []; |
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foreach ( $this->_StrongestPaths as $candidate_key => $challengers_key ) : |
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if ( in_array($candidate_key, $done, true) ) : |
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continue; |
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endif; |
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$winner = true; |
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foreach ($challengers_key as $beaten_key => $beaten_value) : |
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if ( in_array($beaten_key, $done, true) ) : |
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continue; |
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endif; |
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if ( $beaten_value < $this->_StrongestPaths[$beaten_key][$candidate_key] ) : |
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$winner = false; |
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endif; |
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endforeach; |
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if ($winner) : |
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$result[$rank][] = $candidate_key; |
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$to_done[] = $candidate_key; |
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endif; |
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endforeach; |
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$done = array_merge($done, $to_done); |
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$rank++; |
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endwhile; |
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$this->_Result = $this->createResult($result); |
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} |
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} |
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julien-boudry /
Condorcet
