Make Wright method a variant of regular STV as an exclusion method

docs/options.md

@@ -66,10 +66,9 @@ Some STV counting rules provide, for example, that ‘no surplus shall be transf
 
 ## Method (-m/--method)
 
-This dropdown allows you to select how ballots are transferred during surplus transfers or exclusions. The 2 recommended methods are:
+This dropdown allows you to select how ballots are transferred during surplus transfers or exclusions. The recommended method is:
 
 * Weighted inclusive Gregory: During surplus transfers, all applicable ballot papers of the transferring candidate are examined. Transfers are weighted according to the weights of the ballot papers.
-* Wright STV: Same as weighted inclusive Gregory, but when a candidate is excluded, the count is reset from the beginning (minus the excluded candidate).
 
 Other methods are supported, but not recommended:
 
@@ -88,6 +87,7 @@ Other surplus transfer methods, such as non-fractional transfers (e.g. random sa
 * Exclude in one round (default): When excluding a candidate, transfer all their ballot papers in one round.
 * Exclude by parcel (by order): When excluding a candidate, transfer their ballot papers one parcel at a time, in their order each was received. Each parcel forms a separate round, i.e. if a transfer allows another candidate to meet the quota criterion, no further papers are transferred to that candidate.
 * Exclude by value: When excluding a candidate, transfer their ballot papers in descending order of accumulated transfer value. Each transfer of all ballots of a certain transfer value forms a separate round.
+* Wright method (re-iterate): When a candidate is excluded, the count is reset from the beginning (minus the excluded candidate).
 
 ## Ties (-t/--ties)
 

html/index.html

@@ -147,6 +147,7 @@
 					<option value="parcels_by_order">Exclude by parcel (by order)</option>
 					<!--<option value="parcels_by_value">Exclude by parcel (by value)</option>-->
 					<option value="by_value">Exclude by value</option>
+					<option value="wright">Wright method (re-iterate)</option>
 				</select>
 			</label>
 			<br>

html/index.js

@@ -83,9 +83,9 @@ function changePreset() {
 		document.getElementById('chkRoundVotes').checked = false;
 		document.getElementById('chkRoundWeights').checked = false;
 		document.getElementById('selSurplus').value = 'size';
-		document.getElementById('selTransfers').value = 'wright';
+		document.getElementById('selTransfers').value = 'wig';
 		document.getElementById('selPapers').value = 'both';
-		document.getElementById('selExclusion').value = 'one_round';
+		document.getElementById('selExclusion').value = 'wright';
 		document.getElementById('selTies').value = 'backwards_random';
 	} else if (document.getElementById('selPreset').value === 'prsa77') {
 		document.getElementById('selQuotaCriterion').value = 'geq';

html/worker.js

@@ -46,8 +46,6 @@ onmessage = function(evt) {
 			counter = py.pyRCV2.method.base_stv.UIGSTVCounter(election, evt.data.data.options);
 		} else if (evt.data.data.transfers === 'eg') {
 			counter = py.pyRCV2.method.base_stv.EGSTVCounter(election, evt.data.data.options);
-		} else if (evt.data.data.transfers === 'wright') {
-			counter = py.pyRCV2.method.wright.WrightSTVCounter(election, evt.data.data.options);
 		} else {
 			counter = py.pyRCV2.method.base_stv.WIGSTVCounter(election, evt.data.data.options);
 		}

pyRCV2/cli/stv.py

@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -19,7 +19,6 @@ import pyRCV2.model
 import pyRCV2.numbers
 
 from pyRCV2.method.base_stv import UIGSTVCounter, WIGSTVCounter, EGSTVCounter
-from pyRCV2.method.wright import WrightSTVCounter
 from pyRCV2.ties import TiesBackwards, TiesPrompt, TiesRandom
 
 import sys
@@ -37,9 +36,9 @@ def add_parser(subparsers):
 	parser.add_argument('--round-votes', type=int, help='round votes to specified decimal places')
 	parser.add_argument('--round-weights', type=int, help='round ballot weights to specified decimal places')
 	parser.add_argument('--surplus-order', '-s', choices=['size', 'order'], default='size', help='whether to distribute surpluses by size or by order of election (default: size)')
-	parser.add_argument('--method', '-m', choices=['wig', 'uig', 'eg', 'wright'], default='wig', help='method of surpluses and exclusions (default: wig - weighted inclusive Gregory)')
+	parser.add_argument('--method', '-m', choices=['wig', 'uig', 'eg'], default='wig', help='method of transferring surpluses (default: wig - weighted inclusive Gregory)')
 	parser.add_argument('--transferable-only', action='store_true', help='examine only transferable papers during surplus distributions')
-	parser.add_argument('--exclusion', choices=['one_round', 'parcels_by_order', 'by_value'], default='one_round', help='whether to perform exclusions in one round or parcel by parcel (default: one_round)')
+	parser.add_argument('--exclusion', choices=['one_round', 'parcels_by_order', 'by_value', 'wright'], default='one_round', help='how to perform exclusions (default: one_round)')
 	parser.add_argument('--ties', '-t', action='append', choices=['backwards', 'prompt', 'random'], default=None, help='how to resolve ties (default: backwards then random)')
 	parser.add_argument('--random-seed', default=None, help='arbitrary string used to seed the RNG for random tie breaking')
 
@@ -85,8 +84,6 @@ def main(args):
 		counter = UIGSTVCounter(election, vars(args))
 	elif args.method == 'eg':
 		counter = EGSTVCounter(election, vars(args))
-	elif args.method == 'wright':
-		counter = WrightSTVCounter(election, vars(args))
 	else:
 		counter = WIGSTVCounter(election, vars(args))
 	

pyRCV2/method/base_stv.py

@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -67,7 +67,7 @@ class BaseSTVCounter:
 			'quota_criterion': 'geq', # 'geq' or 'gt'
 			'surplus_order': 'size',  # 'size' or 'order'
 			'papers': 'both',         # 'both' or 'transferable'
-			'exclusion': 'one_round', # 'one_round', 'parcels_by_order' or 'by_value'
+			'exclusion': 'one_round', # 'one_round', 'parcels_by_order', 'by_value' or 'wright'
 			'ties': [],               # List of tie strategies (e.g. TiesRandom)
 			'round_votes': None,      # Number of decimal places or None
 			'round_weights': None,    # Number of decimal places or None
@@ -315,6 +315,37 @@ class BaseSTVCounter:
 		candidate_excluded, count_card = self.candidate_to_exclude()
 		count_card.state = CandidateState.EXCLUDING
 		
+		# Handle Wright STV
+		if self.options['exclusion'] == 'wright':
+			count_card.state = CandidateState.EXCLUDED
+			
+			# Reset the count
+			# Carry over certain candidate states
+			new_candidates = SafeDict()
+			for candidate, count_card in self.candidates.items():
+				new_count_card = CountCard()
+				
+				if count_card.state == CandidateState.WITHDRAWN:
+					new_count_card.state = CandidateState.WITHDRAWN
+				elif count_card.state == CandidateState.EXCLUDED:
+					new_count_card.state = CandidateState.EXCLUDED
+				
+				__pragma__('opov')
+				new_candidates[candidate] = new_count_card
+				__pragma__('noopov')
+			
+			self.candidates = new_candidates
+			self.exhausted = CountCard()
+			self.loss_fraction = CountCard()
+			self.num_elected = 0
+			
+			step_results = self.step_results # Carry over step results
+			result = self.reset()
+			self.step_results = step_results
+			result.comment = 'Exclusion of ' + candidate_excluded.name
+			
+			return result
+		
 		# Exclude this candidate
 		self.do_exclusion(candidate_excluded, count_card)
 		

pyRCV2/method/wright.py

@@ -1,61 +0,0 @@
-#   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
-#
-#   This program is free software: you can redistribute it and/or modify
-#   it under the terms of the GNU Affero General Public License as published by
-#   the Free Software Foundation, either version 3 of the License, or
-#   (at your option) any later version.
-#
-#   This program is distributed in the hope that it will be useful,
-#   but WITHOUT ANY WARRANTY; without even the implied warranty of
-#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-#   GNU Affero General Public License for more details.
-#
-#   You should have received a copy of the GNU Affero General Public License
-#   along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-__pragma__ = lambda x: None
-
-from pyRCV2.method.base_stv import WIGSTVCounter
-from pyRCV2.model import CandidateState, CountCard
-from pyRCV2.safedict import SafeDict
-
-class WrightSTVCounter(WIGSTVCounter):
-	"""
-	Wright STV implementation
-	"""
-	
-	def exclude_candidate(self):
-		"""
-		Overrides BaseSTVCounter.exclude_candidate per Wright STV
-		"""
-		
-		candidate_excluded, count_card = self.candidate_to_exclude()
-		count_card.state = CandidateState.EXCLUDED
-		
-		# Reset the count
-		# Carry over certain candidate states
-		new_candidates = SafeDict()
-		for candidate, count_card in self.candidates.items():
-			new_count_card = CountCard()
-			
-			if count_card.state == CandidateState.WITHDRAWN:
-				new_count_card.state = CandidateState.WITHDRAWN
-			elif count_card.state == CandidateState.EXCLUDED:
-				new_count_card.state = CandidateState.EXCLUDED
-			
-			__pragma__('opov')
-			new_candidates[candidate] = new_count_card
-			__pragma__('noopov')
-		
-		self.candidates = new_candidates
-		self.exhausted = CountCard()
-		self.loss_fraction = CountCard()
-		self.num_elected = 0
-		
-		step_results = self.step_results # Carry over step results
-		result = self.reset()
-		self.step_results = step_results
-		result.comment = 'Exclusion of ' + candidate_excluded.name
-		
-		return result

pyRCV2/transcrypt.py

@@ -16,7 +16,7 @@
 
 import pyRCV2.blt
 import pyRCV2.model
-import pyRCV2.method, pyRCV2.method.base_stv, pyRCV2.method.wright
+import pyRCV2.method, pyRCV2.method.base_stv
 import pyRCV2.numbers
 import pyRCV2.random
 import pyRCV2.ties

tests/test_combinations.py

@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -17,7 +17,6 @@
 import pyRCV2.blt
 import pyRCV2.numbers
 import pyRCV2.method.base_stv
-import pyRCV2.method.wright
 from pyRCV2.model import CountCompleted
 
 import json
@@ -63,4 +62,4 @@ def maketst(numbers, counter_cls, options):
 test_prsa1_scottish_py, test_prsa1_scottish_js = maketst('Fixed', 'pyRCV2.method.base_stv.WIGSTVCounter', {})
 test_prsa1_stvc_py, test_prsa1_stvc_js = maketst('Rational', 'pyRCV2.method.base_stv.WIGSTVCounter', {'quota': 'droop_exact', 'quota_criterion': 'gt', 'prog_quota': True})
 test_prsa1_senate_py, test_prsa1_senate_js = maketst('Fixed', 'pyRCV2.method.base_stv.UIGSTVCounter', {'surplus_order': 'order', 'exclusion': 'by_value'})
-test_prsa1_wright_py, test_prsa1_wright_js = maketst('Fixed', 'pyRCV2.method.wright.WrightSTVCounter', {})
+test_prsa1_wright_py, test_prsa1_wright_js = maketst('Fixed', 'pyRCV2.method.base_stv.WIGSTVCounter', {'exclusion': 'wright'})

tests/test_csm.py

@@ -1,5 +1,5 @@
 #   pyRCV2: Preferential vote counting
-#   Copyright © 2020  Lee Yingtong Li (RunasSudo)
+#   Copyright © 2020–2021  Lee Yingtong Li (RunasSudo)
 #
 #   This program is free software: you can redistribute it and/or modify
 #   it under the terms of the GNU Affero General Public License as published by
@@ -19,7 +19,7 @@ from pytest_steps import test_steps
 
 import pyRCV2.blt
 import pyRCV2.numbers
-from pyRCV2.method.wright import WrightSTVCounter
+from pyRCV2.method.base_stv import WIGSTVCounter
 from pyRCV2.model import CandidateState, CountCompleted
 
 def count_until_exclude(counter):
@@ -43,7 +43,7 @@ def test_csm15():
 	
 	cands = {c.name: c for c in election.candidates}
 	
-	counter = WrightSTVCounter(election)
+	counter = WIGSTVCounter(election, {'exclusion': 'wright'})
 	
 	# Round 1
 	result = counter.reset()