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A recipe for calculating the seats allocated to each party in the Knesset.

Python, 103 lines
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103``` ```''' @author: Elazar Gershuni @version: 0.1 Input: two text files in the following formats votes.txt: {name} {votes} agreements.txt: {party a} {party b} (Without actual braces) ''' qualifying_threshold_percentage = 0.02 def read_data(): def read_pairs(filename): '''(This is not the right way to handle resources - we should use a `with` statement. But who cares.)''' yield from (line.strip().split() for line in open(filename, encoding='utf-8')) party_pairs = [(name, int(votes.replace(',', ''))) for name, votes in read_pairs('votes.txt')] return party_pairs, read_pairs('agreements.txt') def prepare_data(party_pairs, agreement_pairs): class Party: def __init__(self, name, votes): self.name = name self.agreement = Agreement([self]) self.votes = votes class Agreement: seats = 0 def __init__(self, parties): self.parties = parties parties = {name:Party(name, votes) for name, votes in party_pairs} for name1, name2 in agreement_pairs: p1, p2 = parties[name1], parties[name2] p1.agreement = p2.agreement = Agreement({p2, p1}) return list(parties.values()) def sum_votes(parties): return sum(p.votes for p in parties) def list_indicator(x): '''The reason for adding 1 is for determining what the indicator would be if the pair would receive that additional seat.''' return x.votes // (x.seats + 1) def filter_parties(parties): total_votes = sum_votes(parties) passed_parties = [p for p in parties if p.votes > total_votes * qualifying_threshold_percentage] for p in passed_parties: p.agreement.parties = [x for x in p.agreement.parties if x in passed_parties] return passed_parties def get_shares(passed_parties): # first phase general_indicator = sum_votes(passed_parties) // 120 for p in passed_parties: p.agreement.seats += p.votes // general_indicator return {p.agreement for p in passed_parties} def mandate_splitting(agreements_list): # second phase seats_so_far = sum(s.seats for s in agreements_list) for s in agreements_list: s.votes = sum_votes(s.parties) for _ in range(seats_so_far, 120): max(agreements_list, key=list_indicator).seats += 1 return agreements_list def split_share(excess_votes_list): for s in excess_votes_list: if len(s.parties) == 1: s.parties[0].seats = s.seats else: # split between sharing parties indicator = s.votes // s.seats for p in s.parties: p.seats = p.votes // indicator max(s.parties, key=list_indicator).seats += 1 def calculate(): parties = filter_parties(prepare_data(*read_data())) split_share(mandate_splitting(get_shares(parties))) return {p.name:p.seats for p in parties} def print_parties(parties): for name, seats in sorted(parties.items(), key=lambda x: x[1], reverse=True): print(name, '=', seats) if __name__ == '__main__': parties = calculate() print_parties(parties) ```
 Created by elazar on Thu, 13 Feb 2014 (MIT)

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