Implement Wright STV

html/index.html

@@ -40,6 +40,7 @@
 					<option value="scottish" selected>Scottish STV</option>
 					<option value="stvc">pyRCV STV-C</option>
 					<option value="senate">Australian Senate STV</option>
+					<option value="wright">Wright STV</option>
 				</select>
 			</label>
 			<button id="btnAdvancedOptions" onclick="clickAdvancedOptions()">Show advanced options</button>
@@ -92,10 +93,11 @@
 				</select>
 			</label>
 			<label>
-				Transfer value:
+				Method:
 				<select id="selTransfers">
 					<option value="wig" selected>Weighted inclusive Gregory</option>
 					<option value="uig">Unweighted inclusive Gregory</option>
+					<option value="wright">Wright STV</option>
 				</select>
 			</label>
 			<br>

html/index.js

@@ -50,11 +50,21 @@ function changePreset() {
 		document.getElementById('selQuotaCriterion').value = 'geq';
 		document.getElementById('selQuota').value = 'droop';
 		document.getElementById('chkProgQuota').checked = false;
-		document.getElementById('chkBulkExclusion').checked = false;
+		document.getElementById('chkBulkExclusion').checked = true;
 		document.getElementById('selNumbers').value = 'int';
 		document.getElementById('selSurplus').value = 'order';
 		document.getElementById('selTransfers').value = 'uig';
 		document.getElementById('selTies').value = 'backwards_random';
+	} else if (document.getElementById('selPreset').value === 'wright') {
+		document.getElementById('selQuotaCriterion').value = 'geq';
+		document.getElementById('selQuota').value = 'droop';
+		document.getElementById('chkProgQuota').checked = false;
+		document.getElementById('chkBulkExclusion').checked = true;
+		document.getElementById('selNumbers').value = 'fixed';
+		document.getElementById('txtDP').value = '5';
+		document.getElementById('selSurplus').value = 'size';
+		document.getElementById('selTransfers').value = 'wright';
+		document.getElementById('selTies').value = 'backwards_random';
 	}
 }
 

html/worker.js

@@ -41,10 +41,12 @@ onmessage = function(evt) {
 	
 	// Create counter
 	let counter;
-	if (evt.data.transfers === 'wig') {
-		counter = py.pyRCV2.method.base_stv.BaseWIGSTVCounter(election, evt.data.options);
-	} else {
+	if (evt.data.transfers === 'uig') {
 		counter = py.pyRCV2.method.base_stv.BaseUIGSTVCounter(election, evt.data.options);
+	} else if (evt.data.transfers === 'wright') {
+		counter = py.pyRCV2.method.wright.WrightSTVCounter(election, evt.data.options);
+	} else {
+		counter = py.pyRCV2.method.base_stv.BaseWIGSTVCounter(election, evt.data.options);
 	}
 	
 	// Reset

pyRCV2/method/base_stv.py

@@ -192,11 +192,7 @@ class BaseSTVCounter:
 		Exclude the lowest ranked hopeful
 		"""
 		
-		hopefuls = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL]
-		hopefuls.sort(lambda x: x[1].votes)
-		
-		# TODO: Handle ties
-		candidate_excluded, count_card = hopefuls[0]
+		candidate_excluded, count_card = self.candidate_to_exclude()
 		count_card.state = CandidateState.EXCLUDED
 		
 		# Exclude this candidate
@@ -221,6 +217,19 @@ class BaseSTVCounter:
 		)
 		__pragma__('noopov')
 	
+	def candidate_to_exclude(self):
+		"""
+		Determine the candidate to exclude
+		"""
+		
+		hopefuls = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL]
+		hopefuls.sort(lambda x: x[1].votes)
+		
+		# TODO: Handle ties
+		candidate_excluded, count_card = hopefuls[0]
+		
+		return candidate_excluded, count_card
+	
 	def do_exclusion(self, candidate_excluded, count_card):
 		"""
 		Exclude the given candidate and transfer the votes

pyRCV2/method/wright.py

@@ -0,0 +1,56 @@
+#   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/>.
+
+from pyRCV2.method.base_stv import BaseWIGSTVCounter
+from pyRCV2.model import CandidateState, CountCard
+from pyRCV2.safedict import SafeDict
+
+class WrightSTVCounter(BaseWIGSTVCounter):
+	"""
+	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
+		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
+		
+		result = self.reset()
+		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
+import pyRCV2.method, pyRCV2.method.base_stv, pyRCV2.method.wright
 import pyRCV2.numbers
 
 __pragma__('js', '{}', 'export {pyRCV2, isinstance, repr, str};')