def summarize(name, results, field):
print
print "== Results from %s" % name
print
print "Votes from %s." % (", ".join(sorted(r[field] for r in results)))
print
rankings = collections.Counter(r[RANK] for r in results).items()
rankings.sort(key=lambda x: x[1], reverse=True)
ballots = []
for order, count in rankings:
print "%3d %s" % (count, order)
ballots.append({
"count": count,
"ballot": [[x] for x in order.split(",")]
})
from pyvotecore.schulze_method import SchulzeMethod
from pyvotecore.condorcet import CondorcetHelper
schulze = SchulzeMethod(
ballots, ballot_notation=CondorcetHelper.BALLOT_NOTATION_GROUPING)
print
if hasattr(schulze, "tied_winners"):
print "*Schulze winners: tie between %s*" % (", ".join(
schulze.tied_winners))
else:
print "*Schulze winner: %s*" % schulze.winner
print
print "Algorithm details:"
print "```"
pprint.pprint(schulze.as_dict())
print "```"
def condorcet_results(self):
result = Condorcet(
list(self.hashes_with_counts(self.ballots_as_rankings())),
ballot_notation=Schulze.BALLOT_NOTATION_RANKING,
).as_dict()
if not result.get('tied_winners'):
return [result['winner']]
else:
return []
def condorcet_results(self):
result = Condorcet(
list(self.hashes_with_counts(self.ballots_as_rankings())),
ballot_notation=Schulze.BALLOT_NOTATION_RANKING,
).as_dict()
if not result.get('tied_winners'):
return [result['winner']]
else:
return []
def test_ranking_format(self):
# Generate data
input = [{
"count": 12,
"ballot": {
"Andrea": 1,
"Brad": 2,
"Carter": 3
}
}, {
"count": 26,
"ballot": {
"Andrea": 1,
"Carter": 2,
"Brad": 3
}
}, {
"count": 12,
"ballot": {
"Andrea": 1,
"Carter": 2,
"Brad": 3
}
}, {
"count": 13,
"ballot": {
"Carter": 1,
"Andrea": 2,
"Brad": 3
}
}, {
"count": 27,
"ballot": {
"Brad": 1
}
}]
output = SchulzeMethod(
input,
ballot_notation=SchulzeMethod.BALLOT_NOTATION_RANKING).as_dict()
# Run tests
self.assertEqual(
output, {
"candidates": set(['Carter', 'Brad', 'Andrea']),
"pairs": {
('Andrea', 'Brad'): 63,
('Brad', 'Carter'): 39,
('Carter', 'Andrea'): 13,
('Andrea', 'Carter'): 50,
('Brad', 'Andrea'): 27,
('Carter', 'Brad'): 51
},
"strong_pairs": {
('Andrea', 'Brad'): 63,
('Carter', 'Brad'): 51,
('Andrea', 'Carter'): 50
},
"winner": 'Andrea'
})
def test_tiebreaker_bug(self):
# Generate data
input = [
{
"count": 1,
"ballot": [["A"], ["B", "C"]]
},
{
"count": 1,
"ballot": [["B"], ["A"], ["C"]]
},
]
output = SchulzeMethod(input, ballot_notation="grouping").as_dict()
# Run tests
self.assertEqual(output['candidates'], set(['A', 'B', 'C']))
self.assertEqual(
output['pairs'], {
('A', 'B'): 1,
('A', 'C'): 2,
('B', 'A'): 1,
('B', 'C'): 1,
('C', 'A'): 0,
('C', 'B'): 0,
})
self.assertEqual(output['strong_pairs'], {
('A', 'C'): 2,
('B', 'C'): 1,
})
self.assertEqual(output['tied_winners'], set(['A', 'B']))
def handle_close(self):
# IMPORTANT! Use deepcopy, we don't want the SchulzePollPlugin to modify our ballots,
# just calculate a result
ballots = deepcopy(self.context.ballots)
if ballots:
schulze_ballots = self.schulze_format_ballots(ballots)
self.context.poll_result = SchulzeMethod(
schulze_ballots, ballot_notation="ranking"
).as_dict()
else:
raise HTTPForbidden(_("No votes, cancel the poll instead."))
def calculateVote(db, event, break_ties=False):
'''Calculate the winner for this event based on current votes'''
#return a dict of all votes for all users for a single event
votes = {}
event_votes = db.query(User.name, Vote.rank, Restaurant.name).join(Vote).join(Restaurant).filter(Vote.event==event.id)
if event_votes.count() > 0:
for user, rank, rest in event_votes.all():
entry = votes.get(user, {})
entry[rest] = rank
votes[user] = entry
#Format the list into the input for Schulze
input = []
for v in votes:
input.append({"count":1, "ballot":copy(votes[v])})
output = SchulzeMethod(input, ballot_notation="rating").as_dict()
tb_user = None
if "tied_winners" in output and break_ties:
#Randomly select a tie-breaker user among those voters tied for the lowest tb_count
users = db.query(User).join(Vote).filter(Vote.event==event.id).order_by(User.tb_count).all()
users = [U for U in users if U.tb_count == users[0].tb_count]
tb_user = random.choice(users)
tb_votes = event_votes.filter(Vote.user == tb_user.id).order_by(Vote.rank.desc()).all()
tb_list = [x[2] for x in tb_votes]
#Update the user's tb_count
tb_user.tb_count += 1
db.commit()
output = SchulzeMethod(input, tie_breaker=tb_list, ballot_notation="rating").as_dict()
return output, tb_user
else:
#No votes?!
return None, ""
def add_ballots(self,
ballots,
tie_breaker=None,
ballot_notation=None,
reverse=False):
"""
Add ballots of ordered issues.
Ballots are translated to their complementary graph using PyVoteCoreAssistance and the graph's
edges values are added/deducted from the IssuesGraph instance.
Example:
input = [{'ballot': [[1], [2], [3], [4], [5]], 'count': 3},
{'ballot': [[5], [2], [3], [4], [1]], 'count': 9},
{'ballot': [[5], [1], [3], [4], [1]], 'count': 8},
{'ballot': [[3], [2], [4], [1], [5]], 'count': 5},
{'ballot': [[1], [2], [3], [4], [5]], 'count': 5}]
g.add_ballots(input)
use reverse=True to deduct the ballot from the IssuesGraph, reversing it's effect.
"""
output = SchulzeMethod(ballots, ballot_notation="grouping").as_dict(
) #TODO: remove this line when iteritems bug is solved
assistance = PyVoteCoreAssistance()
assistance.add_ballot(ballots, tie_breaker, ballot_notation)
for edge_key in assistance.pairs.keys():
try:
from_node = IssueNode.objects.get(issue_id=edge_key[0])
except IssueNode.DoesNotExist:
try:
new_issue = Issue.objects.get(id=edge_key[0])
from_node = self.add_node(new_issue)
except Issue.DoesNotExist:
raise # TODO: decide on proper exception
try:
to_node = IssueNode.objects.get(issue_id=edge_key[1])
except IssueNode.DoesNotExist:
try:
new_issue = Issue.objects.get(id=edge_key[1])
to_node = self.add_node(new_issue)
except Issue.DoesNotExist:
raise # TODO: decide on proper exception
edge = IssueEdge.objects.get(graph=self,
from_node=from_node,
to_node=to_node)
if reverse:
edge.weight -= assistance.pairs[edge_key]
else:
edge.weight += assistance.pairs[edge_key]
edge.save()
def test_grouping_format(self):
# Generate data
input = [
{
"count": 12,
"ballot": [["Andrea"], ["Brad"], ["Carter"]]
},
{
"count": 26,
"ballot": [["Andrea"], ["Carter"], ["Brad"]]
},
{
"count": 12,
"ballot": [["Andrea"], ["Carter"], ["Brad"]]
},
{
"count": 13,
"ballot": [["Carter"], ["Andrea"], ["Brad"]]
},
{
"count": 27,
"ballot": [["Brad"]]
},
]
output = SchulzeMethod(input, ballot_notation="grouping").as_dict()
# Run tests
self.assertEqual(
output, {
"candidates": set(['Carter', 'Brad', 'Andrea']),
"pairs": {
('Andrea', 'Brad'): 63,
('Brad', 'Carter'): 39,
('Carter', 'Andrea'): 13,
('Andrea', 'Carter'): 50,
('Brad', 'Andrea'): 27,
('Carter', 'Brad'): 51
},
"strong_pairs": {
('Andrea', 'Brad'): 63,
('Carter', 'Brad'): 51,
('Andrea', 'Carter'): 50
},
"winner": 'Andrea'
})
def do_POST(self):
try:
# Parse the incoming data
request_raw = self.rfile.read(int(self.headers["content-length"]))
request_raw = re.sub("\n", "", request_raw)
request = json.loads(request_raw)
# Send the data to the requested voting system
if request["voting_system"] == "plurality":
system = Plurality(request["ballots"])
elif request["voting_system"] == "plurality_at_large":
system = PluralityAtLarge(request["ballots"], required_winners = request["winners"])
elif request["voting_system"] == "irv":
system = IRV(request["ballots"])
elif request["voting_system"] == "stv":
system = STV(request["ballots"], required_winners = request["winners"])
elif request["voting_system"] == "schulze_method":
system = SchulzeMethod(request["ballots"], ballot_notation = request["notation"])
elif request["voting_system"] == "schulze_stv":
system = SchulzeSTV(request["ballots"], required_winners = request["winners"], ballot_notation = request["notation"])
elif request["voting_system"] == "schulze_pr":
system = SchulzePR(request["ballots"], winner_threshold = request["winners"], ballot_notation = request["notation"])
else:
raise Exception("No voting system specified")
response = system.as_dict()
# Ensure a response came back from the voting system
if response == None:
raise
except:
fp = StringIO.StringIO()
traceback.print_exc(10,fp)
response = fp.getvalue()
self.send_response(500)
else:
self.send_response(200)
finally:
response = json.dumps(self.__simplify_object__(response))
self.send_header("Content-type", "application/json")
self.send_header("Content-length", str(len(response)))
self.end_headers()
self.wfile.write(response)
def handle_close(self):
"""
Calculate results per round instead. Each round has exactly 1 winner.
(It could be a randomized tie though)
"""
# IMPORTANT! Use deepcopy, we don't want the SortedSchulzePollPlugin to modify our ballots,
# just calculate a result
ballots = deepcopy(self.context.ballots)
wcount = self.context.poll_settings.get("winners", 0)
if ballots:
candidates_left = set(self.context.proposals)
if wcount and len(self.context.proposals) > wcount:
rounds = wcount
else:
rounds = len(self.context.proposals)
schulze_ballots = self.schulze_format_ballots(ballots)
round_data = []
for i in range(rounds):
if len(candidates_left) > 1:
# SchulzeMethod changed the ballots, so we need another copy here!
res = SchulzeMethod(
deepcopy(schulze_ballots), ballot_notation="ranking"
).as_dict()
round_data.append(res)
schulze_ballots = self.eliminate_candidate(
res["winner"], schulze_ballots
)
candidates_left.remove(res["winner"])
else:
# Only 1 candidate left
round_data.append({"winner": list(candidates_left)[0]})
self.context.poll_result = {
"rounds": round_data,
"candidates": set(self.context.proposals),
"winners": [x["winner"] for x in round_data],
}
else:
raise HTTPForbidden(_("No votes, cancel the poll instead."))
def _calculate_results(unresolved):
"""
Given a QuerySet of unresolved topics (with expired deadlines),
resolve them into results, possibly indicating a tie of some sort.
TODO: Handle the case of abstaning being a "winning" option.
"""
extra = ''
for topic in unresolved:
# if topic.agenda.quorum:
# raise Exception, '%d / %d' % (topic.agenda.quorum, topic.num_voters())
if topic.agenda.quorum and topic.num_voters() < topic.agenda.quorum:
# Mark invalid with no results. Somewhat counter-intuitively,
# we consider the results to have been "calculated" in this case
# (specifically, we calculated that there are no valid results).
topic.invalid = True
topic.result_calculated = True
topic.save()
continue
# Currently, proceed with results even if there are fewer results
# than expected. It is conceivable that this is a valid outcome,
# for instance, if only three candidates receive any votes in a Board
# election, then there should be only three winners even though there
# are four or five positions.
options = topic.counted_options().filter(num_votes__gt=0)
num_options = options.count()
if topic.vote_type.name == TYPE_CHARTER:
# Charter amendments require a 2/3 majority.
for_option = options.get(name='For')
against_option = options.get(name='Against')
total_votes = for_option.num_votes + against_option.num_votes
if for_option.num_votes >= (total_votes * (2.0 / 3.0)):
for_option.result = True
for_option.save()
else:
against_option.result = True
against_option.save()
# It's not possible for this sort of measure to tie- it either reaches
# the two-thirds threshold or it does not.
topic.invalid = False
topic.result_calculated = True
topic.save()
extra = ('\n\nPlease note that Charter Amendments require a 2/3 '
'majority to pass.')
elif not topic.vote_type.max_votes:
# evaluate Schulze method. First collect votes, than use library.
voters = User.objects.filter(votes__option__topic=topic).distinct()
options = topic.options.all()
ballots = []
for voter in voters:
votes = Vote.objects.filter(option__in=options, voter=voter)\
.order_by('rank')
ordered_votes = []
last_rank = votes[0].rank - 1
current_rank = 0
for vote in votes:
if vote.rank == last_rank:
ordered_votes[-1].append(vote.option_id)
else:
ordered_votes.append([vote.option_id])
last_rank = vote.rank
current_rank += 1
vote.rank = current_rank
vote.save()
ballot = {'ballot': ordered_votes}
ballots.append(ballot)
result = SchulzeMethod(ballots, ballot_notation="grouping")
if hasattr(result, 'tied_winners'):
# Schulze method can be tied as well, treat as other ties
options = Option.objects.filter(id__in=result.tied_winners)
for option in options:
option.result = True
option.save()
topic.invalid = True
topic.result_calculated = True
topic.save()
else:
option = Option.objects.get(id=result.winner)
option.result = True
option.save()
options = options.exclude(id=result.winner)
for option in options:
option.result = False
option.save()
topic.result_calculated = True
topic.save()
elif topic.vote_type.max_votes <= topic.vote_type.max_winners:
# Flag ties that affect the validity of the results,
# and set any tied options after the valid winning range
# to a "winning" result as well, indicating that they are all
# equally plausible as winners despite producing more winners
# than are allowed.
i = topic.vote_type.max_winners
while (i > 0 and i < num_options
and options[i - 1].num_votes == options[i].num_votes):
topic.invalid = True
# Note that setting options[i].result = True and then
# saving options[i] does not work, probably as a side effect
# of evaluationg the options queryset (it's not actualy an array)
option = options[i]
option.result = True
option.save()
i += 1
# Set all non-tied winning results.
for option in options[0:topic.vote_type.max_winners]:
option.result = True
option.save()
topic.result_calculated = True
topic.save()
else:
return
_send_result_email(topic, extra)
def test_wiki_example2(self):
# Generate data
input = [{
"count": 5,
"ballot": [["A"], ["C"], ["B"], ["E"], ["D"]]
}, {
"count": 5,
"ballot": [["A"], ["D"], ["E"], ["C"], ["B"]]
}, {
"count": 8,
"ballot": [["B"], ["E"], ["D"], ["A"], ["C"]]
}, {
"count": 3,
"ballot": [["C"], ["A"], ["B"], ["E"], ["D"]]
}, {
"count": 7,
"ballot": [["C"], ["A"], ["E"], ["B"], ["D"]]
}, {
"count": 2,
"ballot": [["C"], ["B"], ["A"], ["D"], ["E"]]
}, {
"count": 7,
"ballot": [["D"], ["C"], ["E"], ["B"], ["A"]]
}, {
"count": 8,
"ballot": [["E"], ["B"], ["A"], ["D"], ["C"]]
}]
output = SchulzeMethod(input, ballot_notation="grouping").as_dict()
# Run tests
self.assertEqual(
output, {
'candidates':
set(['A', 'C', 'B', 'E', 'D']),
'pairs': {
('A', 'B'): 20,
('A', 'C'): 26,
('A', 'D'): 30,
('A', 'E'): 22,
('B', 'A'): 25,
('B', 'C'): 16,
('B', 'D'): 33,
('B', 'E'): 18,
('C', 'A'): 19,
('C', 'B'): 29,
('C', 'D'): 17,
('C', 'E'): 24,
('D', 'A'): 15,
('D', 'B'): 12,
('D', 'C'): 28,
('D', 'E'): 14,
('E', 'A'): 23,
('E', 'B'): 27,
('E', 'C'): 21,
('E', 'D'): 31
},
'strong_pairs': {
('B', 'D'): 33,
('E', 'D'): 31,
('A', 'D'): 30,
('C', 'B'): 29,
('D', 'C'): 28,
('E', 'B'): 27,
('A', 'C'): 26,
('B', 'A'): 25,
('C', 'E'): 24,
('E', 'A'): 23
},
'actions': [{
'edges': set([('E', 'A')])
}, {
'edges': set([('C', 'E')])
}, {
'nodes': set(['A', 'C', 'B', 'D'])
}],
'winner':
'E'
})
#!/usr/bin/env python from pyvotecore.schulze_method import SchulzeMethod from pyvotecore.condorcet import CondorcetHelper from allvotes import ballots from pprint import pprint pprint(SchulzeMethod(ballots, ballot_notation = CondorcetHelper.BALLOT_NOTATION_GROUPING).as_dict())