python-vote-core implements various electoral methods, providing the results calculated off a provided set of ballots and options.
- Project page: http://github.com/bradbeattie/python-vote-core
- Issue tracker: http://github.com/bradbeattie/python-vote-core/issues
- Example usage: http://modernballots.com
- Single Winner Methods
- Plurality (aka first-past-the-post or fptp)
- Instant-Runoff Voting (aka IRV)
- Schulze Method (aka Beatpath)
- Multiple Winner Methods
- Plurality at large (aka block voting)
- Single Transferable Vote (aka STV)
- Schulze STV
- Ordering Methods
- Schulze Proportional Representation
- Schulze Nonproportional Representation
Schulze method example:
>>> from pyvotecore.schulze_method import SchulzeMethod
>>> from pyvotecore.condorcet import CondorcetHelper
>>> ballots = [
... { "count":3, "ballot":[["A"], ["C"], ["D"], ["B"]] },
... { "count":9, "ballot":[["B"], ["A"], ["C"], ["D"]] },
... { "count":8, "ballot":[["C"], ["D"], ["A"], ["B"]] },
... { "count":5, "ballot":[["D"], ["A"], ["B"], ["C"]] },
... { "count":5, "ballot":[["D"], ["B"], ["C"], ["A"]] }
... ]
>>> SchulzeMethod(ballots, ballot_notation = CondorcetHelper.BALLOT_NOTATION_GROUPING).as_dict()
{'actions': [{'edges': {('A', 'B')}},
{'edges': {('A', 'C')}},
{'nodes': {'A'}},
{'edges': {('B', 'C')}},
{'nodes': {'B', 'D'}}],
'candidates': {'A', 'B', 'C', 'D'},
'pairs': {('A', 'B'): 16,
('A', 'C'): 17,
('A', 'D'): 12,
('B', 'A'): 14,
('B', 'C'): 19,
('B', 'D'): 9,
('C', 'A'): 13,
('C', 'B'): 11,
('C', 'D'): 20,
('D', 'A'): 18,
('D', 'B'): 21,
('D', 'C'): 10},
'strong_pairs': {('A', 'B'): 16,
('A', 'C'): 17,
('B', 'C'): 19,
('C', 'D'): 20,
('D', 'A'): 18,
('D', 'B'): 21},
'winner': 'C'}