From 673b5314751236208c18fc706708b551743a634c Mon Sep 17 00:00:00 2001
From: RunasSudo <runassudo@yingtongli.me>
Date: Sun, 3 Jan 2021 17:20:13 +1100
Subject: [PATCH] Optimisation: Do not re-sort already sorted parcels in
 exclusion by_value

---
 pyRCV2/method/base_stv.py | 20 +++++++++++++-------
 pyRCV2/model.py           |  1 +
 2 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/pyRCV2/method/base_stv.py b/pyRCV2/method/base_stv.py
index f6751a2..97a8eb9 100644
--- a/pyRCV2/method/base_stv.py
+++ b/pyRCV2/method/base_stv.py
@@ -538,6 +538,7 @@ class WIGSTVCounter(BaseSTVCounter):
 			if len(cand_ballots) > 0:
 				__pragma__('opov')
 				self.candidates[candidate].parcels.append(new_parcel)
+				self.candidates[candidate]._parcels_sorted = False
 				__pragma__('noopov')
 			
 			__pragma__('opov')
@@ -590,13 +591,15 @@ class WIGSTVCounter(BaseSTVCounter):
 			count_card.parcels.remove(parcel)
 		elif self.options['exclusion'] == 'by_value':
 			# Sort the ballots by value
-			ballots = [(b, bv) for p in count_card.parcels for b, bv in p]
-			__pragma__('opov')
-			ballots.sort(key=lambda x: x[1] / x[0].value, reverse=True)
-			# Round to 8 decimal places to consider equality
-			# FIXME: Work out a better way of doing this
-			count_card.parcels = groupby(ballots, lambda x: (x[1] / x[0].value).round(8, x[1].ROUND_DOWN))
-			__pragma__('noopov')
+			if not count_card._parcels_sorted:
+				ballots = [(b, bv) for p in count_card.parcels for b, bv in p]
+				__pragma__('opov')
+				ballots.sort(key=lambda x: x[1] / x[0].value, reverse=True)
+				# Round to 8 decimal places to consider equality
+				# FIXME: Work out a better way of doing this
+				count_card.parcels = groupby(ballots, lambda x: (x[1] / x[0].value).round(8, x[1].ROUND_DOWN))
+				count_card._parcels_sorted = True
+				__pragma__('noopov')
 			
 			if len(count_card.parcels) > 0:
 				parcel = count_card.parcels[0]
@@ -618,6 +621,7 @@ class WIGSTVCounter(BaseSTVCounter):
 			if len(cand_ballots) > 0:
 				__pragma__('opov')
 				self.candidates[candidate].parcels.append(new_parcel)
+				self.candidates[candidate]._parcels_sorted = False
 				__pragma__('noopov')
 			
 			__pragma__('opov')
@@ -669,6 +673,7 @@ class UIGSTVCounter(WIGSTVCounter):
 			if len(cand_ballots) > 0:
 				__pragma__('opov')
 				self.candidates[candidate].parcels.append(new_parcel)
+				self.candidates[candidate]._parcels_sorted = False
 				__pragma__('noopov')
 			
 			__pragma__('opov')
@@ -736,6 +741,7 @@ class EGSTVCounter(UIGSTVCounter):
 			if len(cand_ballots) > 0:
 				__pragma__('opov')
 				self.candidates[candidate].parcels.append(new_parcel)
+				self.candidates[candidate]._parcels_sorted = False
 				__pragma__('noopov')
 			
 			__pragma__('opov')
diff --git a/pyRCV2/model.py b/pyRCV2/model.py
index 520692f..b5b6980 100644
--- a/pyRCV2/model.py
+++ b/pyRCV2/model.py
@@ -71,6 +71,7 @@ class CountCard:
 		# Parcel = List[Tuple[Ballot, Num]]
 		# The exhausted/loss to fraction piles will have only one parcel
 		self.parcels = []
+		self._parcels_sorted = False # Optimisation to avoid re-sorting in exclusion by_value
 	
 	@property
 	def votes(self):