ElectionRunner::getQuota() - Code Metrics - Inspection of "Make some properties public temporarily and add va..." - michaelcullum/voting-lib - Measure and Improve Code Quality continuously with Scrutinizer

Completed

Push — master ( 23a0ba...e10981 )

by Michael

created 2016-08-20 02:24 UTC

ElectionRunner::getQuota() A

↳ Parent: ElectionRunner

Complexity

Conditions	1
Paths	1

Size

Total Lines	12
Code Lines	7

Duplication

Lines	0
Ratio	0 %

Code Coverage

Tests	7
CRAP Score	1

Importance

Changes

Metric	Value
dl	0
loc	12
ccs	7
cts	7
cp	1
rs	9.4285
c	0
b	0
f	0
cc	1
eloc	7
nc	1
nop	0
crap	1

<?php

namespace Michaelc\Voting\STV;

use Psr\Log\LoggerInterface as Logger;
use Michaelc\Voting\Exception\VotingLogicException as LogicException;
use Michaelc\Voting\Exception\VotingRuntimeException as RuntimeException;

/**
 * This class will calculate the outcome of an election
 *
 * References throughout are provided as to what is going on.
 * It follows a system similar to Scottish STV and all paragraph
 * references are for: http://www.legislation.gov.uk/sdsi/2011/9780111014639/pdfs/sdsi_9780111014639_en.pdf
 */
class ElectionRunner
{
    /**
     * Logger.
     *
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;

    /**
     * Election object.
     *
     * @var \Michaelc\Voting\STV\Election;
     */
    protected $election;

    /**
     * Array of all ballots in election.
     *
     * @var \MichaelC\Voting\STV\Ballot[]
     */
    protected $ballots;

    /**
     * Quota of votes needed for a candidate to be elected.
     *
     * @var int
     */
    public $quota;

    /**
     * Number of candidates elected so far.
     *
     * @var int
     */
    public $electedCandidates;

    /**
     * Invalid ballots.
     *
     * @var \MichaelC\Voting\STV\Ballot[]
     */
    public $rejectedBallots;

    /**
     * Number of valid ballots
     *
     * @var int
     */
    public $validBallots;

    /**
     * Number of winners to still be elected (at current stage)
     *
     * @var int
     */
    public $candidatesToElect;

    /**
     * Constructor.
     *
     * @param Election $election
     */
    public function __construct(Election $election, Logger $logger)
    {
        $this->logger = $logger;
        $this->election = $election;

        $this->ballots = $this->election->getBallots();
        $this->rejectedBallots = [];
        $this->candidatesToElect = $this->election->getWinnersCount();
        $this->validBallots = $this->election->getNumBallots();
    }

    /**
     * Run the election.
     *
     * @return Candidate[] Winning candidates
     */
    public function run()
    {
        $this->logger->notice('Starting to run an election');
        $this->logger->notice(sprintf('There are %d candidates, %d ballots and to be %d winners', $this->election->getCandidateCount(), $this->validBallots, $this->election->getWinnersCount()));

        // Reject invalid ballots, then calculate the quota based on remaining valid ballots
        // p. 46(3) and p 47
        $this->rejectInvalidBallots();
        $this->setQuota();

        // First step of standard allocation of ballots
        // p. 46(1) and 46(2)
        $this->firstStep();

        $candidates = $this->election->getActiveCandidates();

        // All the re-allocation rounds until we have filled all seats or
        // have the same number of seats left to fill and candidates remaining
        // (then elect them).
        $this->processReallocationRounds($candidates);
        // p. 53
        $this->reallocateRemainingVotes($candidates);

        $this->logger->notice('Election complete');

        return $this->election->getElectedCandidates();
    }

    /**
     * Perform the initial vote allocation.
     * p. 46
     *
     * @return
     */
    protected function firstStep()
    {
        $this->logger->info('Beginning the first step');

        // Allocate all the ballots
        foreach ($this->ballots as $i => $ballot) {
            $this->allocateVotes($ballot);
        }

        $this->logger->notice('Step 1 complete',
            ['candidatesStatus' => $this->election->getCandidatesStatus()]
        );

        return;
    }

    /**
     * Process re-allocation rounds (elimination re-allocations and surplus re-allocations)
     *
     * @param  Candidate[] $candidates All active candidates to elect
     *
     * @return Candidate[]
     */
    protected function processReallocationRounds(array &$candidates): array
    {
        $counter = 1;
        while (($this->candidatesToElect > 0) && ($this->election->getActiveCandidateCount() > $this->candidatesToElect)) {
            if (!$this->checkCandidates($candidates)) {
                // p. 51(1)
                $this->eliminateCandidates($candidates);
            }

            $candidates = $this->election->getActiveCandidates();

            $counter++;

            $this->logger->notice("Step $counter complete",
                ['candidatesStatus' => $this->election->getCandidatesStatus()]
            );
        }

        return $candidates;
    }

    /**
     * Check if any candidates have reached the quota and can be elected.
     *
     * @param Candidate[] $candidates Array of active candidates to check
     *
     * @return bool Whether any candidates were changed to elected
     */
    protected function checkCandidates(array $candidates): bool
    {
        $elected = false;
        $candidatesToElect = [];

        $this->logger->info('Checking if candidates have passed quota');

        if (empty($candidates))
        {
            throw new LogicException("There are no more candidates left");
        }

        foreach ($candidates as $i => $candidate) {
            if ($candidate->getState() !== Candidate::RUNNING)
            {
                throw new LogicException('Candidate is not marked as not running but has not been excluded');
            }

            $votes = $candidate->getVotes();

            $this->logger->debug("Checking candidate ($candidate) with $votes", ['candidate' => $candidate]);

            // p. 48(1)
            // Immediately elect a candidate if they hit the quota
            // We check all the candidates, see who has hit the quota,
            // add them to a queue, then elect those who have hit the quota to prevent
            // surplus allocations pushing a candidate over the quota early.
            if ($votes >= $this->quota) {
                $candidatesToElect[] = $candidate;
                $elected = true;
            }
        }

        // TODO: Put this in a try, and catch the RuntimeError.
        // Then sort by the surplus, and fill available seats.
        // If have same surplus then select randomly (Contary to Scottish STV)
        // p. 50
        $this->electCandidates($candidatesToElect);

        $this->logger->info(('Candidate checking complete. Elected: ' . count($candidatesToElect)));

        return $elected;
    }

    /**
     * Elect an array of candidates
     *
     * @param  Candidate[] $candidates Array of candidates to elect
     *
     * @return
     */
    protected function electCandidates(array $candidates)
    {
        if ($this->candidatesToElect < count($candidates))
        {
            throw new RuntimeException('Cannot elect candidate as not enough seats to fill');
        }

        foreach ($candidates as $i => $candidate) {
            $this->electCandidate($candidate);
        }

        return;
    }

    /**
     * Allocate the next votes from a Ballot.
     * p. 49
     *
     * @param Ballot $ballot     The ballot to allocate the votes from
     * @param float  $multiplier Number to multiply the weight by (surplus)
     * @param float  $divisor    The divisor of the weight (Total number of
     *                           candidate votes)
     *
     * @return Ballot The same ballot passed in modified
     */
    protected function allocateVotes(Ballot $ballot, float $multiplier = 1.0, float $divisor = 1.0): Ballot
    {
        $currentWeight = $ballot->getWeight();
        // p. 49(3)
        // "A divided by B" Where A = the value which is calculated
        // by multiplying the surplus of the transferring candidate
        // by the value of the ballot paper when received by that candidate; and
        // B = the total number of votes credited to that candidate
        $weight = $ballot->setWeight(($currentWeight * $multiplier) / $divisor);

        // Get the next candidate on their ballot paper which has not been assigned
        // a vote this could be the first candidate in round 1
        $candidate = $ballot->getNextChoice();

        $this->logger->debug("Allocating vote of weight $weight to $candidate. Previous weight: $currentWeight", array(
            'ballot' => $ballot,
        ));

        // Check there was a next candidate, if only x candidates where listed where
        // x < the number of candidates standing this will occur.
        if ($candidate !== null) {
            // Allocate those surplus votes. p. 49(1) and p. 49(2)
            $this->election->getCandidate($candidate)->addVotes($weight);
            $ballot->incrementLevelUsed();
            $this->logger->debug('Vote added to candidate');

            // If the candidate is no longer running due to being defeated or
            // elected then we re-allocate their vote again.
            if (!in_array($candidate, $this->election->getActiveCandidateIds()))
            {
                $this->allocateVotes($ballot);
            }
        }

        return $ballot;
    }

    /**
     * Transfer the votes from one candidate to other candidates.
     *
     * @param float     $surplus   The number of surplus votes to transfer
     * @param Candidate $candidate The candidate being elected to transfer
     *                             the votes from
     *
     * @return
     */
    protected function transferSurplusVotes(float $surplus, Candidate $candidate)
    {
        $totalVotes = $candidate->getVotes();
        $candidateId = $candidate->getId();

        $this->logger->info('Transfering surplus votes');

        foreach ($this->ballots as $i => $ballot) {
            if ($ballot->getLastChoice() == $candidateId) {
                $this->allocateVotes($ballot, $surplus, $totalVotes);
            }
        }

        return;
    }

    /**
     * Transfer the votes from one eliminated candidate to other candidates.
     * p. 51(2)
     *
     * @param Candidate $candidate Candidate being eliminated to transfer
     *                             the votes from
     *
     * @return
     */
    protected function transferEliminatedVotes(Candidate $candidate)
    {
        $candidateId = $candidate->getId();

        $votes = $candidate->getVotes();

        $this->logger->info("Transfering votes from eliminated candidate ($candidate) with $votes votes");

        // p. 51(2)(a) - Sort into next preference candidates
        // p. 51(3) - Add votes to candidates
        // p. 51(4) - Use previous weighting
        foreach ($this->ballots as $i => $ballot) {
            if ($ballot->getLastChoice() == $candidateId) {
                $this->allocateVotes($ballot);
            }
        }

        return;
    }

    /**
     * Elect a candidate after they've passed the threshold.
     *
     * @param Candidate $candidate
     */
    protected function electCandidate(Candidate $candidate)
    {
        $this->logger->notice("Electing a candidate: $candidate");

        $candidate->setState(Candidate::ELECTED);
        $this->electedCandidates++;
        $this->candidatesToElect--;

        if ($this->electedCandidates < $this->election->getWinnersCount()) {
            $surplus = $candidate->getVotes() - $this->quota;
            if ($surplus > 0) {
                $this->transferSurplusVotes($surplus, $candidate);
            } else {
                $this->logger->notice("No surplus votes from $candidate to reallocate");
            }
        }

        return;
    }

    /**
     * Eliminate the candidate with the lowest number of votes
     * and reallocated their votes.
     * p. 51
     *
     * @param Candidate[] $candidates Array of active candidates
     *
     * @return int Number of candidates eliminated
     */
    protected function eliminateCandidates(array $candidates): int
    {
        $minimumCandidates = $this->getLowestCandidates($candidates);
        $count = count($minimumCandidates);

        // p. 52(2)(b) - the returning officer shall decide, by lot, which of those
        // candidates is to be excluded.
        // We do not look back on previous rounds at all as per p. 52(2)(a)
        $minimumCandidate = $minimumCandidates[(array_rand($minimumCandidates))];

        $this->logger->notice(sprintf("There were %d joint lowest candidates,
            %d was randomly selected to be eliminated", $count, $minimumCandidate->getId()));

        $this->transferEliminatedVotes($minimumCandidate);
        $minimumCandidate->setState(Candidate::DEFEATED);

        return count($minimumCandidates);
    }

    /**
     * Get candidates with the lowest number of votes
     * p. 51 and p. 52(1)
     *
     * @param Candidate[] $candidates
     *                                                     Array of active candidates
     *
     * @return Candidate[]
     *                                          Candidates with lowest score
     */
    public function getLowestCandidates(array $candidates): array
    {
        $minimum = count($this->election->getBallots());
        $minimumCandidates = [];

        foreach ($candidates as $i => $candidate) {
            if ($candidate->getVotes() < $minimum) {
                $minimum = $candidate->getVotes();
                unset($minimumCandidates);
                $minimumCandidates[] = $candidate;
            } elseif ($candidate->getVotes() == $minimum) {
                $minimumCandidates[] = $candidate;
                $this->logger->info("Calculated as a lowest candidate: $candidate");
            }
        }

        return $minimumCandidates;
    }

    /**
     * Reject any invalid ballots.
     * p. 46(3)
     *
     * @return int Number of rejected ballots
     */
    protected function rejectInvalidBallots(): int
    {
        foreach ($this->ballots as $i => $ballot) {
            if (!$this->checkBallotValidity($ballot)) {
                $this->rejectedBallots[] = clone $ballot;
                unset($this->ballots[$i]);
            }
        }

        $count = count($this->rejectedBallots);

        $this->logger->notice("Found $count rejected ballots");

        $this->validBallots = $this->validBallots - $count;

        return $count;
    }

    /**
     * Check if ballot is valid.
     *
     * @param Ballot $ballot Ballot to test
     *
     * @return bool True if valid, false if invalid
     */
    public function checkBallotValidity(Ballot $ballot): bool
    {
        $ranking = $ballot->getRanking();

        if (count($ranking) > $this->election->getCandidateCount()) {
            $this->logger->debug('Invalid ballot - number of candidates', ['ballot' => $ballot]);

            return false;
        } elseif (count($ranking) !== count(array_unique($ranking))) {
            return false;
        } else {
            $candidateIds = $this->election->getCandidateIds();

            foreach ($ranking as $i => $candidate) {
                if (!in_array($candidate, $candidateIds)) {
                    $this->logger->debug('Invalid ballot - invalid candidate');

                    return false;
                }
            }
        }

        // TODO: Check for candidates multiple times on the same ballot paper

        $this->logger->debug('Ballot is valid', ['ballot' => $ballot]);

        return true;
    }

    /**
     * Reallocate any remaining votes
     * p. 53
     *
     * @param  Candidate[] $candidates All remaining candidates to elect
     * @return
     */
    protected function reallocateRemainingVotes(array &$candidates)
    {
        if (!empty($candidates))
        {
            $this->logger->info('All votes re-allocated. Electing all remaining candidates');

            if ($this->candidatesToElect < count($candidates))
            {
                throw new LogicException('Cannot elect candidate as no more seats to fill');
            }

            $this->electCandidates($candidates);
        }

        return;
    }

    /**
     * Get the quota to win.
     * p. 47
     *
     * TODO: Move this out of this method and use params/args
     *
     * @return int
     */
    public function setQuota(): int
    {
        $this->quota = floor(
$answer = 42;

$correct = false;

$correct = (bool) $answer;
            ($this->validBallots /
                ($this->election->getWinnersCount() + 1)
            ) // p. 47 (1)
            + 1); // p. 47 (2)

        $this->logger->info(sprintf("Quota set at %d based on %d winners and %d valid ballots", $this->quota, $this->election->getWinnersCount(), $this->validBallots));

        return $this->quota;
    }
}


1		<?php
2
3		namespace Michaelc\Voting\STV;
4
5		use Psr\Log\LoggerInterface as Logger;
6		use Michaelc\Voting\Exception\VotingLogicException as LogicException;
7		use Michaelc\Voting\Exception\VotingRuntimeException as RuntimeException;
8
9		/**
10		* This class will calculate the outcome of an election
11		*
12		* References throughout are provided as to what is going on.
13		* It follows a system similar to Scottish STV and all paragraph
14		* references are for: http://www.legislation.gov.uk/sdsi/2011/9780111014639/pdfs/sdsi_9780111014639_en.pdf
15		*/
16		class ElectionRunner
17		{
18		/**
19		* Logger.
20		*
21		* @var \Psr\Log\LoggerInterface
22		*/
23		protected $logger;
24
25		/**
26		* Election object.
27		*
28		* @var \Michaelc\Voting\STV\Election;
29		*/
30		protected $election;
31
32		/**
33		* Array of all ballots in election.
34		*
35		* @var \MichaelC\Voting\STV\Ballot[]
36		*/
37		protected $ballots;
38
39		/**
40		* Quota of votes needed for a candidate to be elected.
41		*
42		* @var int
43		*/
44		public $quota;
45
46		/**
47		* Number of candidates elected so far.
48		*
49		* @var int
50		*/
51		public $electedCandidates;
52
53		/**
54		* Invalid ballots.
55		*
56		* @var \MichaelC\Voting\STV\Ballot[]
57		*/
58		public $rejectedBallots;
59
60		/**
61		* Number of valid ballots
62		*
63		* @var int
64		*/
65		public $validBallots;
66
67		/**
68		* Number of winners to still be elected (at current stage)
69		*
70		* @var int
71		*/
72		public $candidatesToElect;
73
74		/**
75		* Constructor.
76		*
77		* @param Election $election
78		*/
79	2	public function __construct(Election $election, Logger $logger)
80		{
81	2	$this->logger = $logger;
82	2	$this->election = $election;
83
84	2	$this->ballots = $this->election->getBallots();
85	2	$this->rejectedBallots = [];
86	2	$this->candidatesToElect = $this->election->getWinnersCount();
87	2	$this->validBallots = $this->election->getNumBallots();
88	2	}
89
90		/**
91		* Run the election.
92		*
93		* @return Candidate[] Winning candidates
94		*/
95	1	public function run()
96		{
97	1	$this->logger->notice('Starting to run an election');
98	1	$this->logger->notice(sprintf('There are %d candidates, %d ballots and to be %d winners', $this->election->getCandidateCount(), $this->validBallots, $this->election->getWinnersCount()));
99
100		// Reject invalid ballots, then calculate the quota based on remaining valid ballots
101		// p. 46(3) and p 47
102	1	$this->rejectInvalidBallots();
103	1	$this->setQuota();
104
105		// First step of standard allocation of ballots
106		// p. 46(1) and 46(2)
107	1	$this->firstStep();
108
109	1	$candidates = $this->election->getActiveCandidates();
110
111		// All the re-allocation rounds until we have filled all seats or
112		// have the same number of seats left to fill and candidates remaining
113		// (then elect them).
114	1	$this->processReallocationRounds($candidates);
115		// p. 53
116	1	$this->reallocateRemainingVotes($candidates);
117
118	1	$this->logger->notice('Election complete');
119
120	1	return $this->election->getElectedCandidates();
121		}
122
123		/**
124		* Perform the initial vote allocation.
125		* p. 46
126		*
127		* @return
128		*/
129	1	protected function firstStep()
130		{
131	1	$this->logger->info('Beginning the first step');
132
133		// Allocate all the ballots
134	1	foreach ($this->ballots as $i => $ballot) {
135	1	$this->allocateVotes($ballot);
136		}
137
138	1	$this->logger->notice('Step 1 complete',
139	1	['candidatesStatus' => $this->election->getCandidatesStatus()]
140		);
141
142	1	return;
143		}
144
145		/**
146		* Process re-allocation rounds (elimination re-allocations and surplus re-allocations)
147		*
148		* @param Candidate[] $candidates All active candidates to elect
149		*
150		* @return Candidate[]
151		*/
152	1	protected function processReallocationRounds(array &$candidates): array
153		{
154	1	$counter = 1;
155	1	while (($this->candidatesToElect > 0) && ($this->election->getActiveCandidateCount() > $this->candidatesToElect)) {
156	1	if (!$this->checkCandidates($candidates)) {
157		// p. 51(1)
158	1	$this->eliminateCandidates($candidates);
159		}
160
161	1	$candidates = $this->election->getActiveCandidates();
162
163	1	$counter++;
164
165	1	$this->logger->notice("Step $counter complete",
166	1	['candidatesStatus' => $this->election->getCandidatesStatus()]
167		);
168		}
169
170	1	return $candidates;
171		}
172
173		/**
174		* Check if any candidates have reached the quota and can be elected.
175		*
176		* @param Candidate[] $candidates Array of active candidates to check
177		*
178		* @return bool Whether any candidates were changed to elected
179		*/
180	1	protected function checkCandidates(array $candidates): bool
181		{
182	1	$elected = false;
183	1	$candidatesToElect = [];
184
185	1	$this->logger->info('Checking if candidates have passed quota');
186
187	1	if (empty($candidates))
188		{
189		throw new LogicException("There are no more candidates left");
190		}
191
192	1	foreach ($candidates as $i => $candidate) {
193	1	if ($candidate->getState() !== Candidate::RUNNING)
194		{
195		throw new LogicException('Candidate is not marked as not running but has not been excluded');
196		}
197
198	1	$votes = $candidate->getVotes();
199
200	1	$this->logger->debug("Checking candidate ($candidate) with $votes", ['candidate' => $candidate]);
201
202		// p. 48(1)
203		// Immediately elect a candidate if they hit the quota
204		// We check all the candidates, see who has hit the quota,
205		// add them to a queue, then elect those who have hit the quota to prevent
206		// surplus allocations pushing a candidate over the quota early.
207	1	if ($votes >= $this->quota) {
208	1	$candidatesToElect[] = $candidate;
209	1	$elected = true;
210		}
211		}
212
213		// TODO: Put this in a try, and catch the RuntimeError.
214		// Then sort by the surplus, and fill available seats.
215		// If have same surplus then select randomly (Contary to Scottish STV)
216		// p. 50
217	1	$this->electCandidates($candidatesToElect);
218
219	1	$this->logger->info(('Candidate checking complete. Elected: ' . count($candidatesToElect)));
220
221	1	return $elected;
222		}
223
224		/**
225		* Elect an array of candidates
226		*
227		* @param Candidate[] $candidates Array of candidates to elect
228		*
229		* @return
230		*/
231	1	protected function electCandidates(array $candidates)
232		{
233	1	if ($this->candidatesToElect < count($candidates))
234		{
235		throw new RuntimeException('Cannot elect candidate as not enough seats to fill');
236		}
237
238	1	foreach ($candidates as $i => $candidate) {
239	1	$this->electCandidate($candidate);
240		}
241
242	1	return;
243		}
244
245		/**
246		* Allocate the next votes from a Ballot.
247		* p. 49
248		*
249		* @param Ballot $ballot The ballot to allocate the votes from
250		* @param float $multiplier Number to multiply the weight by (surplus)
251		* @param float $divisor The divisor of the weight (Total number of
252		* candidate votes)
253		*
254		* @return Ballot The same ballot passed in modified
255		*/
256	1	protected function allocateVotes(Ballot $ballot, float $multiplier = 1.0, float $divisor = 1.0): Ballot
257		{
258	1	$currentWeight = $ballot->getWeight();
259		// p. 49(3)
260		// "A divided by B" Where A = the value which is calculated
261		// by multiplying the surplus of the transferring candidate
262		// by the value of the ballot paper when received by that candidate; and
263		// B = the total number of votes credited to that candidate
264	1	$weight = $ballot->setWeight(($currentWeight * $multiplier) / $divisor);
265
266		// Get the next candidate on their ballot paper which has not been assigned
267		// a vote this could be the first candidate in round 1
268	1	$candidate = $ballot->getNextChoice();
269
270	1	$this->logger->debug("Allocating vote of weight $weight to $candidate. Previous weight: $currentWeight", array(
271	1	'ballot' => $ballot,
272		));
273
274		// Check there was a next candidate, if only x candidates where listed where
275		// x < the number of candidates standing this will occur.
276	1	if ($candidate !== null) {
277		// Allocate those surplus votes. p. 49(1) and p. 49(2)
278	1	$this->election->getCandidate($candidate)->addVotes($weight);
279	1	$ballot->incrementLevelUsed();
280	1	$this->logger->debug('Vote added to candidate');
281
282		// If the candidate is no longer running due to being defeated or
283		// elected then we re-allocate their vote again.
284	1	if (!in_array($candidate, $this->election->getActiveCandidateIds()))
285		{
286	1	$this->allocateVotes($ballot);
287		}
288		}
289
290	1	return $ballot;
291		}
292
293		/**
294		* Transfer the votes from one candidate to other candidates.
295		*
296		* @param float $surplus The number of surplus votes to transfer
297		* @param Candidate $candidate The candidate being elected to transfer
298		* the votes from
299		*
300		* @return
301		*/
302	1	protected function transferSurplusVotes(float $surplus, Candidate $candidate)
303		{
304	1	$totalVotes = $candidate->getVotes();
305	1	$candidateId = $candidate->getId();
306
307	1	$this->logger->info('Transfering surplus votes');
308
309	1	foreach ($this->ballots as $i => $ballot) {
310	1	if ($ballot->getLastChoice() == $candidateId) {
311	1	$this->allocateVotes($ballot, $surplus, $totalVotes);
312		}
313		}
314
315	1	return;
316		}
317
318		/**
319		* Transfer the votes from one eliminated candidate to other candidates.
320		* p. 51(2)
321		*
322		* @param Candidate $candidate Candidate being eliminated to transfer
323		* the votes from
324		*
325		* @return
326		*/
327	1	protected function transferEliminatedVotes(Candidate $candidate)
328		{
329	1	$candidateId = $candidate->getId();
330
331	1	$votes = $candidate->getVotes();
332
333	1	$this->logger->info("Transfering votes from eliminated candidate ($candidate) with $votes votes");
334
335		// p. 51(2)(a) - Sort into next preference candidates
336		// p. 51(3) - Add votes to candidates
337		// p. 51(4) - Use previous weighting
338	1	foreach ($this->ballots as $i => $ballot) {
339	1	if ($ballot->getLastChoice() == $candidateId) {
340	1	$this->allocateVotes($ballot);
341		}
342		}
343
344	1	return;
345		}
346
347		/**
348		* Elect a candidate after they've passed the threshold.
349		*
350		* @param Candidate $candidate
351		*/
352	1	protected function electCandidate(Candidate $candidate)
353		{
354	1	$this->logger->notice("Electing a candidate: $candidate");
355
356	1	$candidate->setState(Candidate::ELECTED);
357	1	$this->electedCandidates++;
358	1	$this->candidatesToElect--;
359
360	1	if ($this->electedCandidates < $this->election->getWinnersCount()) {
361	1	$surplus = $candidate->getVotes() - $this->quota;
362	1	if ($surplus > 0) {
363	1	$this->transferSurplusVotes($surplus, $candidate);
364		} else {
365	1	$this->logger->notice("No surplus votes from $candidate to reallocate");
366		}
367		}
368
369	1	return;
370		}
371
372		/**
373		* Eliminate the candidate with the lowest number of votes
374		* and reallocated their votes.
375		* p. 51
376		*
377		* @param Candidate[] $candidates Array of active candidates
378		*
379		* @return int Number of candidates eliminated
380		*/
381	1	protected function eliminateCandidates(array $candidates): int
382		{
383	1	$minimumCandidates = $this->getLowestCandidates($candidates);
384	1	$count = count($minimumCandidates);
385
386		// p. 52(2)(b) - the returning officer shall decide, by lot, which of those
387		// candidates is to be excluded.
388		// We do not look back on previous rounds at all as per p. 52(2)(a)
389	1	$minimumCandidate = $minimumCandidates[(array_rand($minimumCandidates))];
390
391	1	$this->logger->notice(sprintf("There were %d joint lowest candidates,
392	1	%d was randomly selected to be eliminated", $count, $minimumCandidate->getId()));
393
394	1	$this->transferEliminatedVotes($minimumCandidate);
395	1	$minimumCandidate->setState(Candidate::DEFEATED);
396
397	1	return count($minimumCandidates);
398		}
399
400		/**
401		* Get candidates with the lowest number of votes
402		* p. 51 and p. 52(1)
403		*
404		* @param Candidate[] $candidates
405		* Array of active candidates
406		*
407		* @return Candidate[]
408		* Candidates with lowest score
409		*/
410	1	public function getLowestCandidates(array $candidates): array
411		{
412	1	$minimum = count($this->election->getBallots());
413	1	$minimumCandidates = [];
414
415	1	foreach ($candidates as $i => $candidate) {
416	1	if ($candidate->getVotes() < $minimum) {
417	1	$minimum = $candidate->getVotes();
418	1	unset($minimumCandidates);
419	1	$minimumCandidates[] = $candidate;
420	1	} elseif ($candidate->getVotes() == $minimum) {
421	1	$minimumCandidates[] = $candidate;
422	1	$this->logger->info("Calculated as a lowest candidate: $candidate");
423		}
424		}
425
426	1	return $minimumCandidates;
427		}
428
429		/**
430		* Reject any invalid ballots.
431		* p. 46(3)
432		*
433		* @return int Number of rejected ballots
434		*/
435	1	protected function rejectInvalidBallots(): int
436		{
437	1	foreach ($this->ballots as $i => $ballot) {
438	1	if (!$this->checkBallotValidity($ballot)) {
439	1	$this->rejectedBallots[] = clone $ballot;
440	1	unset($this->ballots[$i]);
441		}
442		}
443
444	1	$count = count($this->rejectedBallots);
445
446	1	$this->logger->notice("Found $count rejected ballots");
447
448	1	$this->validBallots = $this->validBallots - $count;
449
450	1	return $count;
451		}
452
453		/**
454		* Check if ballot is valid.
455		*
456		* @param Ballot $ballot Ballot to test
457		*
458		* @return bool True if valid, false if invalid
459		*/
460	2	public function checkBallotValidity(Ballot $ballot): bool
461		{
462	2	$ranking = $ballot->getRanking();
463
464	2	if (count($ranking) > $this->election->getCandidateCount()) {
465	2	$this->logger->debug('Invalid ballot - number of candidates', ['ballot' => $ballot]);
466
467	2	return false;
468	2	} elseif (count($ranking) !== count(array_unique($ranking))) {
469	1	return false;
470		} else {
471	2	$candidateIds = $this->election->getCandidateIds();
472
473	2	foreach ($ranking as $i => $candidate) {
474	2	if (!in_array($candidate, $candidateIds)) {
475	2	$this->logger->debug('Invalid ballot - invalid candidate');
476
477	2	return false;
478		}
479		}
480		}
481
482		// TODO: Check for candidates multiple times on the same ballot paper
483
484	2	$this->logger->debug('Ballot is valid', ['ballot' => $ballot]);
485
486	2	return true;
487		}
488
489		/**
490		* Reallocate any remaining votes
491		* p. 53
492		*
493		* @param Candidate[] $candidates All remaining candidates to elect
494		* @return
495		*/
496	1	protected function reallocateRemainingVotes(array &$candidates)
497		{
498	1	if (!empty($candidates))
499		{
500	1	$this->logger->info('All votes re-allocated. Electing all remaining candidates');
501
502	1	if ($this->candidatesToElect < count($candidates))
503		{
504		throw new LogicException('Cannot elect candidate as no more seats to fill');
505		}
506
507	1	$this->electCandidates($candidates);
508		}
509
510	1	return;
511		}
512
513		/**
514		* Get the quota to win.
515		* p. 47
516		*
517		* TODO: Move this out of this method and use params/args
518		*
519		* @return int
520		*/
521	1	public function setQuota(): int
522		{
523	1	$this->quota = floor(
		0 ignored issues – show Documentation Bug introduced 2016-08-20 02:26 UTC by Report Bug Copy Issue Report The property `$quota` was declared of type `integer`, but `floor($this->validBallot...innersCount() + 1) + 1)` is of type `double`. Maybe add a type cast? This check looks for assignments to scalar types that may be of the wrong type. To ensure the code behaves as expected, it may be a good idea to add an explicit type cast. $answer = 42; $correct = false; $correct = (bool) $answer; Loading history...
524	1	($this->validBallots /
525	1	($this->election->getWinnersCount() + 1)
526		) // p. 47 (1)
527	1	+ 1); // p. 47 (2)
528
529	1	$this->logger->info(sprintf("Quota set at %d based on %d winners and %d valid ballots", $this->quota, $this->election->getWinnersCount(), $this->validBallots));
530
531	1	return $this->quota;
532		}
533		}
534

michaelcullum / voting-lib

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ElectionRunner::getQuota() A

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