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Schulze algorithm

Schule algorithm used to obtain the results for schulze method polls.

Ranks candidates by the Schulze method.

For more information read http://en.wikipedia.org/wiki/Schulze_method.

compute_ranks(candidate_names, weighted_ranking_orders)

Returns the Schulze ranking of candidates.

See http://en.wikipedia.org/wiki/Schulze_method for details.

Parameter candidate_names is a list which contains all the candidate names.

Parameter weighted_ranking_orders is a list of pairs (ranking_order, weight), where: - ranking_order is a list of lists, which allows ties, e.g. [[a, b], [c], [d, e]] represents a = b > c > d = e. - weight is a numerical value, typically the number of voters who choose this ranking_order.

Source code in apps/polls_management/classes/schulze_algorithm/schulze.py 
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def compute_ranks(candidate_names, weighted_ranking_orders):
    """Returns the Schulze ranking of candidates.

    See http://en.wikipedia.org/wiki/Schulze_method for details.

    Parameter candidate_names is a list which contains all the candidate names.

    Parameter weighted_ranking_orders is a list of pairs (ranking_order, weight), where:
    - ranking_order is a list of lists, which allows ties, e.g. [[a, b], [c], [d, e]] represents a = b > c > d = e.
    - weight is a numerical value, typically the number of voters who choose this ranking_order.
    """
    d = _compute_d(weighted_ranking_orders)
    p = _compute_p(d, candidate_names)
    return _rank_p(candidate_names, p)

compute_schulze_ranking(candidate_names, ballots)

Returns the Schulze ranking of candidates, in the case where each ballot is given equal weight.

Parameter candidate_names is a list which contains all the candidate names.

Parameter ballots is a list of ballots, where each ballot is actually a ranking order expressed as a list of lists, e.g. [[a, b], [c], [d, e]] represents a = b > c > d = e.

Source code in apps/polls_management/classes/schulze_algorithm/schulze.py 
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def compute_schulze_ranking(candidate_names, ballots):
    """Returns the Schulze ranking of candidates, in the case where each ballot is given equal weight.

    Parameter candidate_names is a list which contains all the candidate names.

    Parameter ballots is a list of ballots, where each ballot is actually a ranking order expressed as a list of lists,
    e.g. [[a, b], [c], [d, e]] represents a = b > c > d = e.
    """
    weighted_ranking_orders = [(ballot, 1) for ballot in ballots]
    return compute_ranks(candidate_names, weighted_ranking_orders)