Revision 79948f90
| b/stv.py | ||
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decreasing order of preference) and an ordered list of weights |
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(new weights are added to the front of the list). The index of the |
| 63 | 63 |
current preference (for the first count and subsequent rounds) |
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is kept in an index.
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is also kept.
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""" |
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candidates = [] |
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weights = [1.0] |
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index = 0
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current_preference = 0
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_value = 1.0 |
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def __init__(self, candidates=[]): |
| ... | ... | |
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logger = logging.getLogger(SVT_LOGGER) |
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transferred = [] |
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# Keep a hash of ballot moves for logging purposes. |
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# The hash comprises |
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moves = {}
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for ballot in allocated[selected]: |
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reallocated = False |
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i = ballot.index + 1
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i = ballot.current_preference + 1
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while not reallocated and i < len(ballot.candidates): |
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recipient = ballot.candidates[i] |
| 145 | 147 |
if recipient in hopefuls: |
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ballot.index = i
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ballot.current_preference = i
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ballot.add_weight(weight) |
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current_value = ballot.get_value() |
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if recipient in allocated: |
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allocated[recipient].append(ballot) |
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else: |
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allocated[recipient] = [ballot] |
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if recipient in vote_count: |
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vote_count[recipient] += (1 * weight)
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vote_count[recipient] += current_value
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else: |
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vote_count[recipient] = 1 * weight |
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vote_count[recipient] = current_value |
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vote_count[selected] -= current_value |
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reallocated = True |
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if (selected, recipient) in moves: |
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moves[(selected, recipient)] += 1 |
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if (selected, recipient, current_value) in moves:
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moves[(selected, recipient, current_value)] += 1
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else: |
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moves[(selected, recipient)] = 1 |
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moves[(selected, recipient, current_value)] = 1
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transferred.append(ballot) |
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else: |
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i += 1 |
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for move, times in moves.iteritems(): |
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description = "from {0} to {1} {2}*{3}={4}".format(move[0], move[1],
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description = "from {0} to {1} {2}*{3}={4}".format(move[0],
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move[1], |
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times, |
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weight,
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times*weight)
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move[2],
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times*move[2])
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logger.info(LOG_MESSAGE.format(action=Action.TRANSFER, |
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desc=description)) |
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allocated[selected][:] = [x for x in allocated[selected] |
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if x not in transferred ] |
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vote_count[selected] -= (len(transferred) * weight) |
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def count_stv(ballots, seats, rnd_gen=None): |
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"""Performs a SVT vote for the given ballots and number of seats. |
| ... | ... | |
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seed() |
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threshold = int(math.ceil(1 + len(ballots) / (seats + 1)))
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threshold = (1 + len(ballots) / (seats + 1))
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logger = logging.getLogger(SVT_LOGGER) |
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logger.info(LOG_MESSAGE.format(action=Action.THRESHOLD, |
| ... | ... | |
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parser = argparse.ArgumentParser(description='Perform STV') |
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parser.add_argument('--ballots', nargs='?', default='sys.stdin',
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dest='ballots_file', help='input ballots file') |
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parser.add_argument('--seats', nargs='?', default=0,
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dest='seats', help='number of seats') |
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args = parser.parse_args() |
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ballots = [] |
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ballots_file = sys.stdin |
| ... | ... | |
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for ballot in ballots_reader: |
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ballots.append(Ballot(ballot)) |
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(elected, vote_count) = count_stv(ballots, 5) |
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if args.seats == 0: |
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args.seats = len(ballots) / 2 |
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(elected, vote_count) = count_stv(ballots, int(args.seats)) |
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print "Results:" |
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for candidate in elected: |
Also available in: Unified diff