Use python-vote-core to implement a « vote » field
Most of the code is copied from the old vote/ranked_items.py implementation apart from the stats() method which is rewritten to use the library python-vote-core (http://pypi.python.org/pypi/python-vote-core/). Implemented voting methods are: - Condorcet / Schulze - Condorcet / Ranked-Pairs - Instant Run-Off - Schulze Proportional Ranking - Schulze Single Transfer Vote - Schulze NPR Some of them take parameters (number of winners, winner threshold). I'm not sure of their interpretation so the best is to lookup the Wikipedia article to know more. Intermediate statisctics are reported, like when there is multiple-rounds tally to find a winner. « pip install python-vote-core » is necessary to use this extension.
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# w.c.s. - web application for online forms
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# Copyright (C) 2005-2010 Entr'ouvert
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301 USA
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import random
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from quixote.html import htmltext, TemplateIO
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from qommon.form import CompositeWidget, IntWidget, WidgetList, StringWidget, \
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CheckboxWidget, SingleSelectWidget
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from wcs.fields import WidgetField, register_field_class
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from pyvotecore import schulze_method, irv, ranked_pairs, schulze_pr, \
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schulze_stv, schulze_npr
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class VoteWidget(CompositeWidget):
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readonly = False
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def __init__(self, name, value = None, elements = None, **kwargs):
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CompositeWidget.__init__(self, name, value, **kwargs)
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self.element_names = {}
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if kwargs.has_key('title'):
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del kwargs['title']
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if kwargs.has_key('readonly'):
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if kwargs['readonly']:
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self.readonly = True
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del kwargs['readonly']
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if kwargs.has_key('required'):
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if kwargs['required']:
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self.required = True
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del kwargs['required']
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self.randomize_items = False
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if kwargs.has_key('randomize_items'):
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if kwargs['randomize_items']:
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self.randomize_items = True
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del kwargs['randomize_items']
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for v in elements:
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if type(v) is tuple:
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title = v[1]
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key = v[0]
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if type(key) is int:
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name = 'element%d' % v[0]
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elif type(key) in (str, htmltext):
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name = str('element%s' % v[0])
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key = str(key)
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else:
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raise NotImplementedError()
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else:
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title = v
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key = v
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name = 'element%d' % len(self.element_names.keys())
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if value:
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position = value.get(key)
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else:
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position = None
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self.add(IntWidget, name, title = title, value = position, size = 5, **kwargs)
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self.element_names[name] = key
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if self.randomize_items:
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random.shuffle(self.widgets)
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if self.readonly:
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def cmp_w(x, y):
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if x.value is None and y.value is None:
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return 0
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if x.value is None:
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return 1
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if y.value is None:
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return -1
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return cmp(x.value, y.value)
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self.widgets.sort(cmp_w)
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def _parse(self, request):
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values = {}
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for name in self.element_names:
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value = self.get(name)
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values[self.element_names[name]] = value
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if type(value) is not int:
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self.get_widget(name).set_error(IntWidget.TYPE_ERROR)
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self.value = values or None
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def parse(self, request=None):
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value = CompositeWidget.parse(self, request=request)
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for widget in self.widgets:
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if widget.has_error():
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self.set_error(_('Some fields were not filled properly.'))
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break
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return value
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def render_content(self):
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r = TemplateIO(html=True)
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r += htmltext('<ul>')
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for widget in self.get_widgets():
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if widget.has_error():
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r += htmltext('<li class="error"><label>')
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else:
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r += htmltext('<li><label>')
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if self.readonly:
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widget.attrs['disabled'] = 'disabled'
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if widget.value:
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r += htmltext('<input type="hidden" name="%s" value="%s" >') % (
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widget.name, widget.value)
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widget.name = widget.name + 'xx'
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r += widget.render_content()
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r += htmltext('</label>')
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r += widget.title
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r += htmltext('</li>')
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r += htmltext('</ul>')
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return r.getvalue()
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METHODS = {
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'condorcet-schulze': N_('Condorcet-Shulze'),
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'irv': N_('Instant Run-off'),
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'ranked_pairs': N_('Ranked pairs'),
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'schulze-pr': N_('Schulze Proportional Ranking'),
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'schulze-stv': N_('Schulze STV'),
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'schulze-npr': N_('Schulze NPR'),
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}
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class VoteField(WidgetField):
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key = 'vote-field'
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description = N_('Ranked choice vote')
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items = None
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randomize_items = True
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widget_class = VoteWidget
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required_winners = None
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winner_threshold = None
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tallying_method = 'condorcet-schulze'
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def perform_more_widget_changes(self, form, kwargs, edit = True):
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kwargs['elements'] = self.items or []
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kwargs['randomize_items'] = self.randomize_items
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def fill_admin_form(self, form):
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WidgetField.fill_admin_form(self, form)
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form.add(WidgetList, 'items', title = _('Items'), element_type = StringWidget,
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value = self.items, required = True,
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element_kwargs = {'render_br': False, 'size': 50},
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add_element_label = _('Add item'))
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form.add(CheckboxWidget, 'randomize_items', title = _('Randomize Items'),
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value = self.randomize_items)
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form.add(SingleSelectWidget, 'tallying_method', title=_('Tallying method'),
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value=self.tallying_method,
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options=METHODS.items())
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form.add(IntWidget, 'required_winners', title=_('Required winners'),
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value=self.required_winners),
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form.add(IntWidget, 'winner_threshold', title=_('Winner threshold'),
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value=self.winner_threshold),
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def get_admin_attributes(self):
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return WidgetField.get_admin_attributes(self) + ['items',
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'randomize_items', 'tallying_method', 'required_winners',
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'winner_threshold']
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def get_view_value(self, value):
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r = TemplateIO(html=True)
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r += htmltext('<ul>')
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items = value.items()
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items.sort(lambda x,y: cmp(x[1], y[1]))
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for it in items:
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if it[1]:
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r += htmltext('<li>%s: %s</li>') % (it[1], it[0])
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r += htmltext('</ul>')
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return r.getvalue()
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def stats(self, values):
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'''
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Compute vote result using the pyvotecore library.
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'''
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r = TemplateIO(html = True)
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votes = [x.data.get(self.id) for x in values]
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# build ballots
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kwargs = { 'winner_threshold': self.winner_threshold,
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'required_winners': self.required_winners }
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if self.tallying_method == 'condorcet-schulze':
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votes = [{ 'count': 1, 'ballot': x } for x in votes if x]
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method = schulze_method.SchulzeMethod
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elif self.tallying_method == 'irv':
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votes = [ x.items() for x in votes ]
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votes = [ sorted(x, cmp=lambda x,y: cmp(x[1],y[1])) for x in votes ]
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votes = [ {'count':1, 'ballot': [ a for a,b in x ] } for x in votes ]
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method = irv.IRV
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elif self.tallying_method == 'ranked_pairs':
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votes = [{ 'count': 1, 'ballot': x } for x in votes if x]
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method = ranked_pairs.RankedPairs
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elif self.tallying_method == 'schulze-pr':
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votes = [{ 'count': 1, 'ballot': x } for x in votes if x]
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method = schulze_pr.SchulzePR
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elif self.tallying_method == 'schulze-stv':
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votes = [{ 'count': 1, 'ballot': x } for x in votes if x]
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method = schulze_stv.SchulzeSTV
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elif self.tallying_method == 'schulze-npr':
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votes = [{ 'count': 1, 'ballot': x } for x in votes if x]
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method = schulze_npr.SchulzeNPR
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else:
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raise ValueError, 'unknown method', self.tallying_method
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# Restrain arguments
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accepted_args = method.__init__.im_func.func_code.co_varnames
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for key in kwargs.keys():
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if key not in accepted_args or kwargs.get(key) is None:
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del kwargs[key]
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# Run vote
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result = method(votes, **kwargs).as_dict()
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r += htmltext('<h4>%s</h4>') % _('Method')
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r += htmltext('<p>%s</p>') % _(METHODS.get(self.tallying_method))
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if 'candidates' in result:
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r += htmltext('<h4>%s</h4>') % _('Candidates')
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r += htmltext('<p>%s</p>') % (', '.join(result['candidates']))
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if 'quota' in result:
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r += htmltext('<h4>%s</h4>') % _('Quota')
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r += htmltext('<p>%s</p>') % result.get('quota')
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if 'rounds' in result:
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for i, _round in enumerate(result['rounds']):
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r += htmltext('<h4>%s</h4><div class="round">') % (_('Round %s') % (i+1))
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if 'loser' in _round:
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r += htmltext('<h5>%s</h5>') % _('Loser')
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r += htmltext('<p>%s</p>') % _round['loser']
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if 'tallies' in _round:
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r += htmltext('<h5>%s</h5><ul>') % _('Tallies')
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for a, b in _round['tallies'].iteritems():
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r += htmltext('<li>%s: %s</li>') % (a,b)
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r += htmltext('</ul>')
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if 'tied_losers' in _round:
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r += htmltext('<h5>%s</h5>') % _('Tied losers')
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r += htmltext('<p>%s</p>') % ', '.join(list(_round['tied_losers']))
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if 'winner' in _round:
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r += htmltext('<h5>%s</h5>') % _('Winner')
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r += htmltext('<p>%s</p>') % _round['winner']
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r += htmltext('</div>')
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if 'pairs' in result:
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r += htmltext('<h4>%s</h4><dl>') % _('Pairs')
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for a, b in result['pairs'].iteritems():
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r += htmltext('<dt>%s</dt>') % ', '.join(a)
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r += htmltext('<dd>%s</dd>') % b
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r += htmltext('</dl>')
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if 'strong_pairs' in result:
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r += htmltext('<h4>%s</h4><dl>') % _('Strong pairs')
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for a, b in result['strong_pairs'].iteritems():
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r += htmltext('<dt>%s</dt>') % ', '.join(a)
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r += htmltext('<dd>%s</dd>') % b
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r += htmltext('</dl>')
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if 'winner' in result:
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r += htmltext('<h4>%s</h4>') % _('Winner')
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r += htmltext('<p>%s</p>') % result['winner']
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if 'winners' in result:
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r += htmltext('<h4>%s</h4>') % _('Winners')
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r += htmltext('<p>%s</p>') % ', '.join(result['winners'])
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if 'order' in result:
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r += htmltext('<h4>%s</h4>') % _('Order')
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r += htmltext('<p>%s</p>') % ', '.join(result['order'])
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# FIXME: show actions
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# import pprint
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# r += htmltext('<pre>%s</pre>') % pprint.pformat(result)
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return r.getvalue()
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register_field_class(VoteField)
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