STVPoll 0.2.0

Example

Case from: https://en.wikipedia.org/wiki/Single_transferable_vote

from stvpoll.scottish_stv import ScottishSTV

example_ballots = (
    (('orange',), 4),
    (('pear', 'orange',), 2),
    (('chocolate', 'strawberry',), 8),
    (('chocolate', 'bonbon',), 4),
    (('strawberry',), 1),
    (('bonbon',), 1),
)

poll = ScottishSTV(seats=3, candidates=('orange', 'chocolate', 'pear', 'strawberry', 'bonbon'))
for (candidates, bcount) in example_ballots:
    poll.add_ballot(candidates, bcount)

result = poll.calculate()

This will return a ElectionResult object that contains the result and some useful metadata. The elected attribute contains the elected candidates.

Candidates to the left have higher preference, so: [‘pear’, ‘orange’] means ‘pear’ before ‘orange’ etc. The number is how many of that kind of ballot there is.

result.elected
[<Candidate: chocolate>, <Candidate: orange>, <Candidate: strawberry>]

Code & Contributions

You may fork the code at: https://github.com/VoteIT/STVPoll

Please report any bugs there, or email info@voteit.se

0.2.0 (dev)

• Fixed bug in deciding which vote to transfer first when multiple elected in Scottish STV. [schyffel] [robinharms]

• Scottish STV: Resolve ties so that winners are always in correct ranking order (extreme case). [schyffel]

• Now works on Python 3. [schyffel]

• Test coverage 100 %. [schyffel]

0.1.4 (2018-05-12)

• Fixed a situation where primary_candidate in rounds didn’t exist. [schyffel] [robinharms]

0.1.3 (2018-03-22)

• Excluded empty ballots, so that they do not affect the quota. [schyffel]

0.1.2 (2017-11-24)

• Fixed exception on empty ballots. [schyffel]

0.1.1 (2017-11-24)

• Fixed case where randomization caused an exception. [schyffel]

0.1.0 (2017-11-03)

• Initial version