Basic election counting logic

build.sh

@@ -1,2 +1,16 @@
 #!/bin/env bash
-transcrypt pyRCV2.transcrypt && rollup __target__/pyRCV2.transcrypt.js -o bundle.js --name py -f iife --no-treeshake
+# Transcrypt
+transcrypt $@ --nomin pyRCV2.transcrypt || exit 1
+
+# Patch next() to accept optional argument
+perl -0777 -i -pe 's#function py_next \(iterator\) {#function py_next \(iterator, def = undefined\) { try { return py_next_orig \(iterator\); } catch \(exception\) { if \(def !== "undefined"\) { return def; } else { throw exception; } } } function py_next_orig \(iterator\) {#g' __target__/org.transcrypt.__runtime__.js || exit 1
+# Patch sum() to accept optional argument
+perl -0777 -i -pe 's#export function sum \(iterable\) {\n    let result = 0;#export function sum \(iterable, result = 0\) { for \(let item of iterable\) { result = __add__\(result, item\); } return result;#g' __target__/org.transcrypt.__runtime__.js || exit 1
+# Patch sort() to use operator overloading
+perl -0777 -i -pe 's#key \(a\) > key \(b\) \?#__gt__\(key \(a\), key \(b\)\) \?#g' __target__/org.transcrypt.__runtime__.js || exit 1
+
+# Roll up
+rollup __target__/pyRCV2.transcrypt.js -o bundle.js --name py -f iife --no-treeshake || exit 1
+
+# Patch
+perl -0777 -i -pe "s#'__index0__'#__index0__#g" bundle.js || exit 1

pyRCV2/blt.py

@@ -14,8 +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/>.
 
-from pyRCV2.model import *
-from pyRCV2.numbers import *
+from pyRCV2.model import Ballot, Candidate, Election
+from pyRCV2.numbers import Num
 
 class BLTException(Exception):
 	pass
@@ -47,11 +47,11 @@ def readBLT(data):
 	
 	# Read candidates
 	for k in range(j + 1, j + 1 + num_candidates):
-		election.candidates.append(Candidate(lines[k].strip('"')))
+		election.candidates.append(Candidate(lines[k][1:-1]))
 	
 	# Read name
 	if j + 1 + num_candidates < len(lines):
-		election.name = lines[j + 1 + num_candidates].strip('"')
+		election.name = lines[j + 1 + num_candidates][1:-1]
 	
 	# Any additional data?
 	if len(lines) > j + 2 + num_candidates and len(lines[j + 2 + num_candidates]) > 0:

pyRCV2/method/STVCCounter.py

@@ -0,0 +1,180 @@
+#   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.model import CandidateState, CountCard, CountCompleted, CountStepResult
+from pyRCV2.numbers import Num
+from pyRCV2.safedict import SafeDict
+
+class STVCCounter:
+	"""Count an STV election using pyRCV STV-C rules"""
+	
+	def __init__(self, election):
+		self.election = election
+	
+	def reset(self):
+		self.candidates = SafeDict([(c, CountCard()) for c in self.election.candidates])
+		self.exhausted = CountCard()
+		
+		# Withdraw candidates
+		for candidate in self.election.withdrawn:
+			__pragma__('opov')
+			self.candidates[candidate].state = CandidateState.WITHDRAWN
+			__pragma__('noopov')
+		
+		# Distribute first preferences
+		for ballot in self.election.ballots:
+			__pragma__('opov')
+			candidate = next((c for c in ballot.preferences if self.candidates[c].state == CandidateState.HOPEFUL), None)
+			
+			if candidate is not None:
+				self.candidates[candidate].transfers += ballot.value
+				self.candidates[candidate].ballots.append((ballot, ballot.value))
+			else:
+				self.exhausted.transfers += ballot.value
+				self.exhausted.ballots.append((ballot, ballot.value))
+			__pragma__('noopov')
+		
+		self.compute_quota()
+		self.elect_meeting_quota()
+		
+		return CountStepResult(
+			'First preferences',
+			self.candidates,
+			self.exhausted,
+			self.quota
+		)
+	
+	def step(self):
+		# Step count cards
+		for candidate, count_card in self.candidates.items():
+			count_card.step()
+		self.exhausted.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:
+			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:
+			# 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
+			
+			return CountStepResult(
+				'Bulk election',
+				self.candidates,
+				self.exhausted,
+				self.quota
+			)
+		
+		# Do surpluses need to be distributed?
+		__pragma__('opov')
+		has_surplus = [(c, cc) for c, cc in self.candidates.items() if cc.state == CandidateState.PROVISIONALLY_ELECTED and cc.votes > self.quota]
+		__pragma__('noopov')
+		
+		if len(has_surplus) > 0:
+			# Distribute surpluses in order of size
+			has_surplus.sort(lambda x: x[1].votes, True)
+			candidate, count_card = has_surplus[0]
+			count_card.state = CandidateState.ELECTED
+			
+			__pragma__('opov')
+			surplus = count_card.votes - self.quota
+			transfer_value = surplus / self.quota
+			count_card.transfers -= surplus
+			__pragma__('noopov')
+			
+			# Transfer surplus
+			for ballot, ballot_value in count_card.ballots:
+				__pragma__('opov')
+				new_value = ballot_value * transfer_value
+				candidate = next((c for c in ballot.preferences if self.candidates[c].state == CandidateState.HOPEFUL), None)
+				
+				if candidate is not None:
+					self.candidates[candidate].transfers += new_value
+					self.candidates[candidate].ballots.append((ballot, new_value))
+				else:
+					self.exhausted.transfers += new_value
+					self.exhausted.ballots.append((ballot, new_value))
+				__pragma__('noopov')
+			
+			# Declare any candidates meeting the quota as a result of surpluses
+			self.compute_quota()
+			self.elect_meeting_quota()
+			
+			return CountStepResult(
+				'Surplus',
+				self.candidates,
+				self.exhausted,
+				self.quota
+			)
+		
+		# Insufficient winners and no surpluses to distribute
+		# 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, count_card = hopefuls[0]
+		count_card.state = CandidateState.EXCLUDED
+		__pragma__('opov')
+		count_card.transfers -= count_card.votes
+		__pragma__('noopov')
+		
+		# Exclude this candidate
+		for ballot, ballot_value in count_card.ballots:
+			__pragma__('opov')
+			candidate = next((c for c in ballot.preferences if self.candidates[c].state == CandidateState.HOPEFUL), None)
+			
+			if candidate is not None:
+				self.candidates[candidate].transfers += ballot_value
+				self.candidates[candidate].ballots.append((ballot, ballot_value))
+			else:
+				self.exhausted.transfers += ballot_value
+				self.exhausted.ballots.append((ballot, ballot_value))
+			__pragma__('noopov')
+		
+		# Declare any candidates meeting the quota as a result of exclusion
+		self.compute_quota()
+		self.elect_meeting_quota()
+		
+		return CountStepResult(
+			'Exclusion',
+			self.candidates,
+			self.exhausted,
+			self.quota
+		)
+	
+	def compute_quota(self):
+		# Compute quota
+		__pragma__('opov')
+		total = sum((cc.votes for c, cc in self.candidates.items()), Num('0'))
+		self.quota = total / Num(self.election.seats)
+		__pragma__('noopov')
+	
+	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')
+		
+		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

pyRCV2/model.py

@@ -14,9 +14,26 @@
 #   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.numbers import Num
+
 class Candidate:
 	def __init__(self, name):
 		self.name = name
+	
+	def __repr__(self):
+		return '<Candidate ' + self.name + '>'
+	
+	def toString(self):
+		return repr(self)
+
+class CandidateState:
+	HOPEFUL = 0
+	PROVISIONALLY_ELECTED = 1
+	ELECTED = 2
+	EXCLUDED = 3
+	WITHDRAWN = 4
 
 class Ballot:
 	def __init__(self, value, preferences):
@@ -34,3 +51,36 @@ class Election:
 		self.candidates = candidates if candidates is not None else []
 		self.ballots = ballots if ballots is not None else []
 		self.withdrawn = withdrawn if withdrawn is not None else []
+
+class CountCard:
+	"""
+	Represents a Candidate's (or exhausted pile) current progress in the count
+	"""
+	def __init__(self):
+		self.orig_votes = Num('0')
+		self.transfers = Num('0')
+		self.ballots = []
+		self.state = CandidateState.HOPEFUL
+	
+	@property
+	def votes(self):
+		__pragma__('opov')
+		return self.orig_votes + self.transfers
+		__pragma__('noopov')
+	
+	def step(self):
+		"""Roll over previous round transfers in preparation for next round"""
+		self.orig_votes = self.votes
+		self.transfers = Num('0')
+
+class CountCompleted:
+	pass
+
+class CountStepResult:
+	def __init__(self, comment, candidates, exhausted, quota):
+		self.comment = comment
+		
+		self.candidates = candidates # SafeDict: Candidate -> CountCard
+		self.exhausted = exhausted # CountCard
+		
+		self.quota = quota

pyRCV2/numbers/__init__.py

@@ -25,7 +25,7 @@ if is_py:
 	from pyRCV2.numbers.rational_py import Rational
 	__pragma__('noskip')
 else:
-	from pyRCV2.numbers.rational_py import Rational
+	from pyRCV2.numbers.rational_js import Rational
 
 _numclass = Rational
 

pyRCV2/numbers/rational_js.py

@@ -18,11 +18,23 @@ class Rational:
 	def __init__(self, val):
 		self.impl = bigRat(val)
 	
+	def pp(self, dp):
+		return self.impl.valueOf().toFixed(dp)
+	
 	def __add__(self, other):
-		return self.impl.add(other.impl)
+		return Rational(self.impl.add(other.impl))
 	def __sub__(self, other):
-		return self.impl.subtract(other.impl)
+		return Rational(self.impl.subtract(other.impl))
 	def __mul__(self, other):
-		return self.impl.multiply(other.impl)
+		return Rational(self.impl.multiply(other.impl))
 	def __div__(self, other):
-		return self.impl.divide(other.impl)
+		return Rational(self.impl.divide(other.impl))
+	
+	def __gt__(self, other):
+		return self.impl.greater(other.impl)
+	def __ge__(self, other):
+		return self.impl.greaterOrEquals(other.impl)
+	def __lt__(self, other):
+		return self.impl.lesser(other.impl)
+	def __le__(self, other):
+		return self.impl.lesserOrEquals(other.impl)

pyRCV2/numbers/rational_py.py

@@ -14,15 +14,30 @@
 #   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 fractions import Fraction
+
 class Rational:
 	def __init__(self, val):
-		self.impl = int(val)
+		self.impl = Fraction(val)
+	
+	def pp(self, dp):
+		"""Pretty print to specified number of decimal places"""
+		return format(self.impl, '.{}f'.format(dp))
 	
 	def __add__(self, other):
-		return self.impl + other.impl
+		return Rational(self.impl + other.impl)
 	def __sub__(self, other):
-		return self.impl - other.impl
+		return Rational(self.impl - other.impl)
 	def __mul__(self, other):
-		return self.impl * other.impl
+		return Rational(self.impl * other.impl)
 	def __div__(self, other):
-		return self.impl / other.impl
+		return Rational(self.impl / other.impl)
+	
+	def __gt__(self, other):
+		return self.impl > other.impl
+	def __ge__(self, other):
+		return self.impl >= other.impl
+	def __lt__(self, other):
+		return self.impl < other.impl
+	def __le__(self, other):
+		return self.impl <= other.impl

pyRCV2/safedict/__init__.py

@@ -0,0 +1,28 @@
+#   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
+is_py = False
+__pragma__('skip')
+is_py = True
+__pragma__('noskip')
+
+if is_py:
+	__pragma__('skip')
+	from pyRCV2.safedict.safedict_py import SafeDict
+	__pragma__('noskip')
+else:
+	from pyRCV2.safedict.safedict_js import SafeDict

pyRCV2/safedict/safedict_js.py

@@ -0,0 +1,35 @@
+#   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/>.
+
+class SafeDict:
+	"""Dictionary which can contain non-string keys in both Python and JS"""
+	
+	def __init__(self, params=None):
+		self.impl = __new__(Map)
+		
+		if params:
+			for k, v in params:
+				self.impl.set(k, v)
+	
+	def __getitem__(self, key):
+		return self.impl.js_get(key)
+	
+	def __setitem__(self, key, value):
+		self.impl.set(key, value)
+	
+	def items(self):
+		entries = self.impl.entries() # Returns an Iterator
+		return __pragma__('js', 'Array.from(entries)')

pyRCV2/safedict/safedict_py.py

@@ -0,0 +1,33 @@
+#   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/>.
+
+class SafeDict:
+	"""Dictionary which can contain non-string keys in both Python and JS"""
+	
+	def __init__(self, params=None):
+		if params:
+			self.impl = {k: v for k, v in params}
+		else:
+			self.impl = {}
+	
+	def __getitem__(self, key):
+		return self.impl[key]
+	
+	def __setitem__(self, key, value):
+		self.impl[key] = value
+	
+	def items(self):
+		return self.impl.items()

pyRCV2/transcrypt.py

@@ -16,6 +16,7 @@
 
 import pyRCV2.blt
 import pyRCV2.model
+import pyRCV2.method, pyRCV2.method.STVCCounter
 import pyRCV2.numbers
 
-__pragma__('js', '{}', 'export {pyRCV2, str, repr};')
+__pragma__('js', '{}', 'export {pyRCV2, isinstance, repr, str};')

test.html

@@ -8,15 +8,130 @@
 		<input type="file" id="bltFile">
 		<button onclick="clickBtn();">OK</button>
 		
+		<table id="result"></table>
+		
 		<script src="http://peterolson.github.com/BigRational.js/BigInt_BigRat.min.js"></script>
 		<script src="bundle.js"></script>
 		
 		<script>
 			async function clickBtn() {
+				// Read BLT file
 				let bltFile = document.getElementById('bltFile').files[0];
 				let text = await bltFile.text();
+				
 				let election = py.pyRCV2.blt.readBLT(text);
-				console.log(election);
+				
+				// Create counter
+				let counter = py.pyRCV2.method.STVCCounter.STVCCounter(election);
+				
+				// Reset
+				let result = counter.reset();
+				
+				// Initialise table rows
+				let tblResults = document.getElementById('result');
+				let candMap = new Map(); // Map Candidate -> rows
+				
+				// Comment row
+				let elComment = document.createElement('tr');
+				let elTd = document.createElement('td');
+				elComment.appendChild(elTd);
+				tblResults.appendChild(elComment);
+				
+				// Candidates
+				for (let candidate of election.candidates) {
+					let elTr1 = document.createElement('tr');
+					let elTr2 = document.createElement('tr');
+					
+					elTd = document.createElement('td');
+					elTd.setAttribute('rowspan', '2');
+					elTd.style.borderTop = '1px solid black';
+					elTd.innerText = candidate.py_name;
+					elTr1.appendChild(elTd);
+					
+					tblResults.appendChild(elTr1);
+					tblResults.appendChild(elTr2);
+					
+					candMap.set(candidate, [elTr1, elTr2]);
+				}
+				
+				// Exhausted votes row
+				let elExhausted1 = document.createElement('tr');
+				let elExhausted2 = document.createElement('tr');
+				
+				elTd = document.createElement('td');
+				elTd.setAttribute('rowspan', '2');
+				elTd.style.borderTop = '1px solid black';
+				elTd.innerText = 'Exhausted';
+				elExhausted1.appendChild(elTd);
+				
+				tblResults.appendChild(elExhausted1);
+				tblResults.appendChild(elExhausted2);
+				
+				// Quota row
+				let elQuota = document.createElement('tr');
+				elTd = document.createElement('td');
+				elTd.style.borderTop = '1px solid black';
+				elTd.innerText = 'Quota';
+				elQuota.appendChild(elTd);
+				tblResults.appendChild(elQuota);
+				
+				// Step election
+				result = counter.reset();
+				
+				do {
+					// Display results
+					elTd = document.createElement('td');
+					elTd.innerText = result.comment;
+					elComment.appendChild(elTd);
+					
+					for (let [candidate, countCard] of result.candidates.impl) {
+						[elTr1, elTr2] = candMap.get(candidate);
+						
+						elTd = document.createElement('td');
+						elTd.style.borderTop = '1px solid black';
+						if (!countCard.transfers.impl.equals(0)) {
+							elTd.innerText = countCard.transfers.pp(2);
+						}
+						elTr1.appendChild(elTd);
+						
+						elTd = document.createElement('td');
+						if (countCard.state == py.pyRCV2.model.CandidateState.WITHDRAWN) {
+							elTd.innerText = 'WD';
+						} else if (countCard.state == py.pyRCV2.model.CandidateState.ELECTED || countCard.state == py.pyRCV2.model.CandidateState.PROVISIONALLY_ELECTED) {
+							elTd.innerText = countCard.votes.pp(2);
+							elTd.style.fontWeight = 'bold';
+						} else if (countCard.state == py.pyRCV2.model.CandidateState.EXCLUDED) {
+							elTd.innerText = 'EX';
+						} else {
+							elTd.innerText = countCard.votes.pp(2);
+						}
+						elTr2.appendChild(elTd);
+					}
+					
+					// Display exhausted votes
+					elTd = document.createElement('td');
+					elTd.style.borderTop = '1px solid black';
+					if (!result.exhausted.transfers.impl.equals(0)) {
+						elTd.innerText = result.exhausted.transfers.pp(2);
+					}
+					elExhausted1.appendChild(elTd);
+					
+					elTd = document.createElement('td');
+					elTd.innerText = result.exhausted.votes.pp(2);
+					elExhausted2.appendChild(elTd);
+					
+					// Display quota
+					elTd = document.createElement('td');
+					elTd.style.borderTop = '1px solid black';
+					elTd.innerText = result.quota.pp(2);
+					elQuota.appendChild(elTd);
+					
+					// Step election
+					result = counter.step();
+					if (py.isinstance(result, py.pyRCV2.model.CountCompleted)) {
+						break;
+					}
+				} while (true);
 			}
 		</script>
 	</body>