Customisable options for STV count in backend

pyRCV2/method/base_stv.py

@@ -20,12 +20,26 @@ from pyRCV2.model import CandidateState, CountCard, CountCompleted, CountStepRes
 from pyRCV2.numbers import Num
 from pyRCV2.safedict import SafeDict
 
-class STVCCounter:
-	"""Count an STV election using pyRCV STV-C rules"""
+class STVException(Exception):
+	pass
 
-	def __init__(self, election):
+class BaseSTVCounter:
+	"""Basic STV counter for various different variations"""
+	
+	def __init__(self, election, options=None):
 		self.election = election
 		
+		# Default options
+		self.options = {
+			'prog_quota': False, # Progressively reducing quota?
+			'quota': 'droop', # 'droop', 'droop_exact', 'hare' or 'hare_exact'
+			'quota_criterion': 'geq', # 'geq' or 'gt'
+			'surplus_order': 'size', # 'size' or 'order'
+		}
+		
+		if options is not None:
+			self.options.update(options)
+	
 	def reset(self):
 		self.candidates = SafeDict([(c, CountCard()) for c in self.election.candidates])
 		self.exhausted = CountCard()
@@ -33,6 +47,8 @@ class STVCCounter:
 		
 		self.total_orig = sum((b.value for b in self.election.ballots), Num('0'))
 		
+		self.num_elected = 0
+		
 		# Withdraw candidates
 		for candidate in self.election.withdrawn:
 			__pragma__('opov')
@@ -52,6 +68,7 @@ class STVCCounter:
 				self.exhausted.ballots.append((ballot, ballot.value))
 			__pragma__('noopov')
 		
+		self.quota = None
 		self.compute_quota()
 		self.elect_meeting_quota()
 		
@@ -74,15 +91,19 @@ class STVCCounter:
 		self.loss_fraction.step()
 		
 		# Have sufficient candidates been elected?
-		if sum(1 for c, cc in self.candidates.items() if cc.state == CandidateState.PROVISIONALLY_ELECTED or cc.state == CandidateState.ELECTED) >= self.election.seats:
+		if self.num_elected >= self.election.seats:
 			return CountCompleted()
 		
 		# Are there just enough candidates to fill all the seats
-		if sum(1 for c, cc in self.candidates.items() if cc.state == CandidateState.PROVISIONALLY_ELECTED or cc.state == CandidateState.ELECTED or cc.state == CandidateState.HOPEFUL) <= self.election.seats:
+		if self.num_elected + sum(1 for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL) <= self.election.seats:
+			# TODO: Sort by size
+			
 			# Declare elected all remaining candidates
 			for candidate, count_card in self.candidates.items():
 				if count_card.state == CandidateState.HOPEFUL:
 					count_card.state = CandidateState.PROVISIONALLY_ELECTED
+					count_card.order_elected = self.num_elected
+					self.num_elected += 1
 			
 			__pragma__('opov')
 			return CountStepResult(
@@ -101,8 +122,14 @@ class STVCCounter:
 		__pragma__('noopov')
 		
 		if len(has_surplus) > 0:
-			# Distribute surpluses in order of size
-			has_surplus.sort(lambda x: x[1].votes, True)
+			# Distribute surpluses in specified order
+			if self.options['surplus_order'] == 'size':
+				has_surplus.sort(lambda x: x[1].votes, True)
+			elif self.options['surplus_order'] == 'order':
+				has_surplus.sort(lambda x: x[1].order_elected)
+			else:
+				raise STVException('Invalid surplus order option')
+			
 			candidate_surplus, count_card = has_surplus[0]
 			count_card.state = CandidateState.ELECTED
 			
@@ -185,20 +212,43 @@ class STVCCounter:
 		__pragma__('noopov')
 	
 	def compute_quota(self):
-		# Compute quota
+		"""Recount total votes and (if applicable) recalculate the quota"""
 		__pragma__('opov')
 		self.total = sum((cc.votes for c, cc in self.candidates.items()), Num('0'))
 		self.loss_fraction.transfers += (self.total_orig - self.total - self.exhausted.votes) - self.loss_fraction.votes
-		self.quota = self.total / Num(self.election.seats + 1)
+		
+		if self.quota is None or self.options['prog_quota']:
+			if self.options['quota'] == 'droop':
+				self.quota = (self.total / Num(self.election.seats + 1)).__floor__() + Num('1')
+			elif self.options['quota'] == 'droop_exact':
+				self.quota = self.total / Num(self.election.seats + 1)
+			elif self.options['quota'] == 'hare':
+				self.quota = (self.total / Num(self.election.seats)).__floor__() + Num('1')
+			elif self.options['quota'] == 'hare_exact':
+				self.quota = self.total / Num(self.election.seats)
+			else:
+				raise STVException('Invalid quota option')
 		__pragma__('noopov')
 	
+	def meets_quota(self, count_card):
+		if self.options['quota_criterion'] == 'geq':
+			__pragma__('opov')
+			return count_card.votes >= self.quota
+			__pragma__('noopov')
+		elif self.options['quota_criterion'] == 'gt':
+			__pragma__('opov')
+			return count_card.votes > self.quota
+			__pragma__('noopov')
+		else:
+			raise STVException('Invalid quota criterion')
+	
 	def elect_meeting_quota(self):
 		# Does a candidate meet the quota?
-		__pragma__('opov')
-		meets_quota = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL and cc.votes > self.quota]
-		__pragma__('noopov')
+		meets_quota = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.HOPEFUL and self.meets_quota(cc)]
 		
 		if len(meets_quota) > 0:
 			# Declare elected any candidate who meets the quota
 			for candidate, count_card in meets_quota:
 				count_card.state = CandidateState.PROVISIONALLY_ELECTED
+				count_card.order_elected = self.num_elected
+				self.num_elected += 1

pyRCV2/model.py

@@ -61,6 +61,7 @@ class CountCard:
 		self.transfers = Num('0')
 		self.ballots = []
 		self.state = CandidateState.HOPEFUL
+		self.order_elected = None
 	
 	@property
 	def votes(self):

pyRCV2/numbers/fixed_js.py

@@ -48,3 +48,6 @@ class Fixed:
 		return self.impl.lt(other.impl)
 	def __le__(self, other):
 		return self.impl.lte(other.impl)
+	
+	def __floor__(self):
+		return Fixed(Math.floor(self.impl))

pyRCV2/numbers/fixed_py.py

@@ -15,6 +15,7 @@
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 from decimal import Decimal
+import math
 
 _quantize_exp = 6
 
@@ -51,3 +52,6 @@ class Fixed:
 		return self.impl < other.impl
 	def __le__(self, other):
 		return self.impl <= other.impl
+	
+	def __floor__(self):
+		return Fixed(math.floor(self.impl))

pyRCV2/numbers/int_js.py

@@ -43,3 +43,6 @@ class NativeInt:
 		return self.impl < other.impl
 	def __le__(self, other):
 		return self.impl <= other.impl
+	
+	def __floor__(self):
+		return NativeInt(Math.floor(self.impl))

pyRCV2/numbers/int_py.py

@@ -14,6 +14,8 @@
 #   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/>.
 
+import math
+
 class NativeInt:
 	"""
 	Wrapper for Python int
@@ -43,3 +45,6 @@ class NativeInt:
 		return self.impl < other.impl
 	def __le__(self, other):
 		return self.impl <= other.impl
+	
+	def __floor__(self):
+		return NativeInt(math.floor(self.impl))

pyRCV2/numbers/native_js.py

@@ -43,3 +43,6 @@ class Native:
 		return self.impl < other.impl
 	def __le__(self, other):
 		return self.impl <= other.impl
+	
+	def __floor__(self):
+		return Native(Math.floor(self.impl))

pyRCV2/numbers/native_py.py

@@ -14,6 +14,8 @@
 #   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/>.
 
+import math
+
 class Native:
 	"""
 	Wrapper for Python float (naive floating-point arithmetic)
@@ -43,3 +45,6 @@ class Native:
 		return self.impl < other.impl
 	def __le__(self, other):
 		return self.impl <= other.impl
+	
+	def __floor__(self):
+		return Native(math.floor(self.impl))

pyRCV2/numbers/rational_js.py

@@ -43,3 +43,6 @@ class Rational:
 		return self.impl.lesser(other.impl)
 	def __le__(self, other):
 		return self.impl.lesserOrEquals(other.impl)
+	
+	def __floor__(self):
+		return Rational(self.impl.floor())

pyRCV2/numbers/rational_py.py

@@ -15,6 +15,7 @@
 #   along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 from fractions import Fraction
+import math
 
 class Rational:
 	"""
@@ -45,3 +46,6 @@ class Rational:
 		return self.impl < other.impl
 	def __le__(self, other):
 		return self.impl <= other.impl
+	
+	def __floor__(self):
+		return Rational(math.floor(self.impl))

pyRCV2/transcrypt.py

@@ -16,7 +16,7 @@
 
 import pyRCV2.blt
 import pyRCV2.model
-import pyRCV2.method, pyRCV2.method.STVCCounter
+import pyRCV2.method, pyRCV2.method.base_stv
 import pyRCV2.numbers
 
 __pragma__('js', '{}', 'export {pyRCV2, isinstance, repr, str};')

test.html

@@ -167,7 +167,6 @@
 							} else if (countCard.state === py.pyRCV2.model.CandidateState.ELECTED || countCard.state === py.pyRCV2.model.CandidateState.PROVISIONALLY_ELECTED) {
 								elTd.classList.add('elected');
 								elTd.innerText = countCard.votes;
-								elTd.style.fontWeight = 'bold';
 								
 								elTr1.querySelector('td:first-child').classList.add('elected');
 							} else if (countCard.state === py.pyRCV2.model.CandidateState.EXCLUDED) {

worker.js

@@ -24,7 +24,7 @@ onmessage = async function(evt) {
 	}});
 	
 	// Create counter
-	let counter = py.pyRCV2.method.STVCCounter.STVCCounter(election);
+	let counter = py.pyRCV2.method.base_stv.BaseSTVCounter(election);
 	
 	// Reset
 	let result = counter.reset();