Implement TransferTable for surpluses (WIP)

src/numbers/fixed.rs

@@ -206,9 +206,7 @@ impl ops::Sub for Fixed {
 
 impl ops::Mul for Fixed {
 	type Output = Self;
-	fn mul(self, _rhs: Self) -> Self::Output {
+	fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0 / get_factor()) }
-		todo!()
-	}
 }
 
 impl ops::Div for Fixed {
@@ -294,8 +292,9 @@ impl ops::MulAssign<&Self> for Fixed {
 }
 
 impl ops::DivAssign<&Self> for Fixed {
-	fn div_assign(&mut self, _rhs: &Self) {
+	fn div_assign(&mut self, rhs: &Self) {
-		todo!()
+		self.0 *= get_factor();
+		self.0 /= &rhs.0;
 	}
 }
 

src/numbers/gfixed.rs

@@ -238,9 +238,7 @@ impl ops::Sub for GuardedFixed {
 
 impl ops::Mul for GuardedFixed {
 	type Output = Self;
-	fn mul(self, _rhs: Self) -> Self::Output {
+	fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0 / get_factor())}
-		todo!()
-	}
 }
 
 impl ops::Div for GuardedFixed {
@@ -326,8 +324,9 @@ impl ops::MulAssign<&Self> for GuardedFixed {
 }
 
 impl ops::DivAssign<&Self> for GuardedFixed {
-	fn div_assign(&mut self, _rhs: &Self) {
+	fn div_assign(&mut self, rhs: &Self) {
-		todo!()
+		self.0 *= get_factor();
+		self.0 /= &rhs.0;
 	}
 }
 

src/numbers/native.rs

@@ -109,9 +109,7 @@ impl ops::Sub for NativeFloat64 {
 
 impl ops::Mul for NativeFloat64 {
 	type Output = NativeFloat64;
-	fn mul(self, _rhs: Self) -> Self::Output {
+	fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0) }
-		todo!()
-	}
 }
 
 impl ops::Div for NativeFloat64 {
@@ -188,9 +186,7 @@ impl ops::MulAssign<&NativeFloat64> for NativeFloat64 {
 }
 
 impl ops::DivAssign<&NativeFloat64> for NativeFloat64 {
-	fn div_assign(&mut self, _rhs: &NativeFloat64) {
+	fn div_assign(&mut self, rhs: &NativeFloat64) { self.0 /= &rhs.0; }
-		todo!()
-	}
 }
 
 impl ops::RemAssign<&NativeFloat64> for NativeFloat64 {

src/numbers/rational_num.rs

@@ -186,9 +186,7 @@ impl ops::Sub for Rational {
 
 impl ops::Mul for Rational {
 	type Output = Rational;
-	fn mul(self, _rhs: Self) -> Self::Output {
+	fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0) }
-		todo!()
-	}
 }
 
 impl ops::Div for Rational {
@@ -265,9 +263,7 @@ impl ops::MulAssign<&Rational> for Rational {
 }
 
 impl ops::DivAssign<&Rational> for Rational {
-	fn div_assign(&mut self, _rhs: &Rational) {
+	fn div_assign(&mut self, rhs: &Rational) { self.0 /= &rhs.0 }
-		todo!()
-	}
 }
 
 impl ops::RemAssign<&Rational> for Rational {

src/numbers/rational_rug.rs

@@ -185,9 +185,7 @@ impl ops::Sub for Rational {
 
 impl ops::Mul for Rational {
 	type Output = Self;
-	fn mul(self, _rhs: Self) -> Self::Output {
+	fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0) }
-		todo!()
-	}
 }
 
 impl ops::Div for Rational {
@@ -264,9 +262,7 @@ impl ops::MulAssign<&Self> for Rational {
 }
 
 impl ops::DivAssign<&Self> for Rational {
-	fn div_assign(&mut self, _rhs: &Self) {
+	fn div_assign(&mut self, rhs: &Self) { self.0 /= &rhs.0 }
-		todo!()
-	}
 }
 
 impl ops::RemAssign<&Self> for Rational {

src/stv/gregory.rs

@@ -15,7 +15,7 @@
  *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-use super::{ExclusionMethod, NextPreferencesEntry, STVError, STVOptions, SumSurplusTransfersMode, SurplusMethod, SurplusOrder};
+use super::{ExclusionMethod, STVError, STVOptions, SurplusMethod, SurplusOrder};
 use super::sample;
 
 use crate::constraints;
@@ -25,7 +25,6 @@ use crate::stv::transfers::TransferTable;
 use crate::ties;
 
 use std::cmp::max;
-use std::collections::HashMap;
 use std::ops;
 
 /// Distribute first preference votes according to the Gregory method
@@ -168,97 +167,23 @@ where
 /// Return the denominator of the surplus fraction
 ///
 /// Returns `None` if the value of transferable votes <= surplus (i.e. all transferable votes are transferred at values received).
-fn calculate_surplus_denom<'n, N: Number>(surplus: &N, transferable_ballots: &'n N, transferable_votes: &'n N, total_ballots: &'n N, total_votes: &'n N, weighted: bool, transferable_only: bool) -> Option<&'n N>
+fn calculate_surplus_denom<'n, N: Number>(surplus: &N, transferable_ballots: &'n N, transferable_votes: &'n N, total_ballots: &'n N, total_votes: &'n N, opts: &STVOptions) -> Option<N>
 where
 	for<'r> &'r N: ops::Sub<&'r N, Output=N>
 {
-	if transferable_only {
+	if opts.transferable_only {
-		let transferable_units = if weighted { transferable_votes } else { transferable_ballots };
+		let transferable_units = if opts.surplus.is_weighted() { transferable_votes } else { transferable_ballots };
 		
 		if transferable_votes > surplus {
-			return Some(transferable_units);
+			return Some(transferable_units.clone());
 		} else {
 			return None;
 		}
 	} else {
-		if weighted {
+		if opts.surplus.is_weighted() {
-			return Some(total_votes);
+			return Some(total_votes.clone());
 		} else {
-			return Some(total_ballots);
+			return Some(total_ballots.clone());
-		}
-	}
-}
-
-/// Return the reweighted value fraction of a parcel/vote after being transferred
-fn reweight_value_fraction<N: Number>(
-	value_fraction: &N,
-	surplus: &N,
-	weighted: bool,
-	surplus_fraction: &Option<N>,
-	surplus_denom: &Option<&N>,
-	round_tvs: Option<usize>) -> N
-{
-	let result;
-	
-	match surplus_denom {
-		Some(v) => {
-			if let Some(_) = round_tvs {
-				// Rounding requested: use the rounded transfer value
-				if weighted {
-					result = value_fraction.clone() * surplus_fraction.as_ref().unwrap();
-				} else {
-					result = surplus_fraction.as_ref().unwrap().clone();
-				}
-			} else {
-				// Avoid unnecessary rounding error by first multiplying by the surplus
-				if weighted {
-					result = value_fraction.clone() * surplus / *v;
-				} else {
-					result = surplus.clone() / *v;
-				}
-			}
-		}
-		None => {
-			result = value_fraction.clone();
-		}
-	}
-	
-	return result;
-}
-
-/// Compute the number of votes to credit to a continuing candidate during a surplus transfer, based on [STVOptions::sum_surplus_transfers]
-fn sum_surplus_transfers<N: Number>(entry: &NextPreferencesEntry<N>, orig_value_fraction: &N, surplus: &N, is_weighted: bool, surplus_fraction: &Option<N>, surplus_denom: &Option<&N>, _state: &mut CountState<N>, opts: &STVOptions) -> N
-where
-	for<'r> &'r N: ops::Mul<&'r N, Output=N>,
-	for<'r> &'r N: ops::Div<&'r N, Output=N>,
-{
-	match opts.sum_surplus_transfers {
-		SumSurplusTransfersMode::ByValue => {
-			// Calculate transfer across all votes in this parcel
-			let mut result = N::new();
-			for vote in entry.votes.iter() {
-				result += &vote.ballot.orig_value;
-			}
-			result *= reweight_value_fraction(orig_value_fraction, surplus, is_weighted, surplus_fraction, surplus_denom, opts.round_surplus_fractions);
-			return result;
-		}
-		SumSurplusTransfersMode::PerBallot => {
-			// Sum transfer per each individual ballot
-			// TODO: This could be moved to distribute_surplus to avoid looping over the votes and calculating transfer values twice
-			let mut new_value_fraction = reweight_value_fraction(orig_value_fraction, surplus, is_weighted, surplus_fraction, surplus_denom, opts.round_surplus_fractions);
-			if let Some(dps) = opts.round_votes {
-				new_value_fraction.floor_mut(dps);
-			}
-			
-			let mut result = N::new();
-			for vote in entry.votes.iter() {
-				let mut vote_value = &new_value_fraction * &vote.ballot.orig_value;
-				if let Some(dps) = opts.round_votes {
-					vote_value.floor_mut(dps);
-				}
-				result += vote_value;
-			}
-			return result;
 		}
 	}
 }
@@ -320,13 +245,7 @@ where
 		parcels_next_prefs.push((parcel.value_fraction, result));
 	}
 	
-	// Calculate surplus fraction
+	// Calculate and print surplus fraction
-	
-	let is_weighted = match opts.surplus {
-		SurplusMethod::WIG => { true }
-		SurplusMethod::UIG | SurplusMethod::EG => { false }
-		_ => unreachable!()
-	};
 	
 	let total_ballots = &transferable_ballots + &exhausted_ballots;
 	let total_votes = &transferable_votes + &exhausted_votes;
@@ -334,15 +253,20 @@ where
 	let count_card = state.candidates.get_mut(elected_candidate).unwrap();
 	count_card.ballot_transfers = -&total_ballots;
 	
-	let surplus_denom = calculate_surplus_denom(&surplus, &transferable_ballots, &transferable_votes, &total_ballots, &total_votes, is_weighted, opts.transferable_only);
+	let mut surplus_denom = calculate_surplus_denom(&surplus, &transferable_ballots, &transferable_votes, &total_ballots, &total_votes, opts);
+	let surplus_numer;
 	let mut surplus_fraction;
-	match surplus_denom {
+	match &surplus_denom {
 		Some(v) => {
 			surplus_fraction = Some(surplus.clone() / v);
 			
 			// Round down if requested
 			if let Some(dps) = opts.round_surplus_fractions {
 				surplus_fraction.as_mut().unwrap().floor_mut(dps);
+				surplus_numer = surplus_fraction.clone();
+				surplus_denom = None;
+			} else {
+				surplus_numer = Some(surplus.clone());
 			}
 			
 			if opts.transferable_only {
@@ -361,6 +285,8 @@ where
 		}
 		None => {
 			surplus_fraction = None;
+			surplus_numer = None;
+			surplus_denom = None;
 			
 			// This can only happen if --transferable-only
 			if transferable_ballots == N::one() {
@@ -373,41 +299,44 @@ where
 	
 	// Reweight and transfer parcels
 	
-	let mut candidate_transfers: HashMap<&Candidate, N> = HashMap::new();
+	let mut transfer_table = TransferTable::new();
-	for candidate in state.election.candidates.iter() {
-		candidate_transfers.insert(candidate, N::new());
-	}
-	let mut exhausted_transfers = N::new();
 	
 	for (value_fraction, result) in parcels_next_prefs {
 		for (candidate, entry) in result.candidates.into_iter() {
 			// Record transfers
-			// TODO: Is there a better way of writing this?
+			transfer_table.add_transfers(&value_fraction, candidate, &entry.num_ballots);
-			let transfers_orig = candidate_transfers.remove(candidate).unwrap();
+			
-			let transfers_add = sum_surplus_transfers(&entry, &value_fraction, &surplus, is_weighted, &surplus_fraction, &surplus_denom, state, opts);
+			let mut new_value_fraction;
-			candidate_transfers.insert(candidate, transfers_orig + transfers_add);
+			if opts.surplus.is_weighted() {
+				new_value_fraction = value_fraction.clone();
+				new_value_fraction *= surplus_numer.as_ref().unwrap(); // Guaranteed to be Some in WIGM
+				if let Some(n) = &surplus_denom {
+					new_value_fraction /= n;
+				}
+			} else {
+				if let Some(sf) = &surplus_fraction {
+					new_value_fraction = sf.clone();
+				} else {
+					new_value_fraction = value_fraction.clone();
+				}
+			}
+			
+			if let Some(dps) = opts.round_values {
+				new_value_fraction.floor_mut(dps);
+			}
 			
 			// Transfer candidate votes
 			let parcel = Parcel {
 				votes: entry.votes,
-				value_fraction: reweight_value_fraction(&value_fraction, &surplus, is_weighted, &surplus_fraction, &surplus_denom, opts.round_surplus_fractions),
+				value_fraction: new_value_fraction,
 				source_order: state.num_elected + state.num_excluded,
 			};
 			let count_card = state.candidates.get_mut(candidate).unwrap();
-			count_card.ballot_transfers += parcel.num_ballots();
 			count_card.parcels.push(parcel);
 		}
 		
 		// Record exhausted votes
-		if opts.transferable_only {
+		transfer_table.add_exhausted(&value_fraction, &result.exhausted.num_ballots);
-			if transferable_votes > surplus {
-				// No ballots exhaust
-			} else {
-				exhausted_transfers += &surplus - &transferable_votes;
-			}
-		} else {
-			exhausted_transfers += sum_surplus_transfers(&result.exhausted, &value_fraction, &surplus, is_weighted, &surplus_fraction, &surplus_denom, state, opts);
-		}
 		
 		// Transfer exhausted votes
 		let parcel = Parcel {
@@ -415,29 +344,13 @@ where
 			value_fraction: value_fraction, // TODO: Reweight exhausted votes
 			source_order: state.num_elected + state.num_excluded,
 		};
-		state.exhausted.ballot_transfers += parcel.num_ballots();
 		state.exhausted.parcels.push(parcel);
 	}
 	
 	let mut checksum = N::new();
 	
 	// Credit transferred votes
-	// ballot_transfers updated above
+	checksum += transfer_table.apply_to(state, opts, Some(&surplus), &surplus_numer, &surplus_denom);
-	for (candidate, mut votes) in candidate_transfers {
-		if let Some(dps) = opts.round_votes {
-			votes.floor_mut(dps);
-		}
-		let count_card = state.candidates.get_mut(candidate).unwrap();
-		count_card.transfer(&votes);
-		checksum += votes;
-	}
-	
-	// Credit exhausted votes
-	if let Some(dps) = opts.round_votes {
-		exhausted_transfers.floor_mut(dps);
-	}
-	state.exhausted.transfer(&exhausted_transfers);
-	checksum += exhausted_transfers;
 	
 	// Finalise candidate votes
 	let count_card = state.candidates.get_mut(elected_candidate).unwrap();
@@ -690,7 +603,7 @@ where
 	}
 	
 	// Credit transferred votes
-	checksum += transfer_table.apply_to(state, opts);
+	checksum += transfer_table.apply_to(state, opts, None, &None, &None);
 	
 	if !votes_remain {
 		// Finalise candidate votes

src/stv/mod.rs

@@ -403,6 +403,15 @@ impl SurplusMethod {
 			SurplusMethod::Hare => "--surplus hare",
 		}.to_string()
 	}
+	
+	/// Returns `true` if this is a weighted method
+	pub fn is_weighted(&self) -> bool {
+		return match self {
+			SurplusMethod::WIG => { true }
+			SurplusMethod::UIG | SurplusMethod::EG => { false }
+			_ => unreachable!()
+		};
+	}
 }
 
 impl<S: AsRef<str>> From<S> for SurplusMethod {

src/stv/transfers.rs

@@ -15,7 +15,7 @@
  *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-use super::STVOptions;
+use super::{STVOptions, SumSurplusTransfersMode};
 
 use crate::election::{Candidate, CountState};
 use crate::numbers::Number;
@@ -74,8 +74,9 @@ impl<'e, N: Number> TransferTable<'e, N> {
 	/// Apply the transfers described in the table to the count sheet
 	///
 	/// Credit continuing candidates and exhausted pile with the appropriate number of ballot papers and votes.
-	pub fn apply_to(&self, state: &mut CountState<N>, opts: &STVOptions) -> N {
+	pub fn apply_to(&self, state: &mut CountState<N>, opts: &STVOptions, surplus: Option<&N>, surplus_numer: &Option<N>, surplus_denom: &Option<N>) -> N {
-		// TODO: SumSurplusTransfers
+		// Use weighted rules if exclusion or WIGM
+		let is_weighted = surplus.is_none() || opts.surplus.is_weighted();
 		
 		let mut checksum = N::new();
 		
@@ -84,13 +85,73 @@ impl<'e, N: Number> TransferTable<'e, N> {
 			let mut votes_transferred = N::new();
 			let mut ballots_transferred = N::new();
 			
-			for column in self.columns.iter() {
+			// If exclusion, or surplus at present value, or SumSurplusTransfersMode::ByValue
-				if let Some(cell) = column.cells.get(*candidate) {
+			if surplus_numer.is_none() || opts.sum_surplus_transfers == SumSurplusTransfersMode::ByValue {
-					votes_transferred += cell.ballots.clone() * &column.value_fraction;
+				// Calculate transfer across all votes in this parcel
-					ballots_transferred += &cell.ballots;
+				for column in self.columns.iter() {
+					if let Some(cell) = column.cells.get(*candidate) {
+						if is_weighted {
+							votes_transferred += cell.ballots.clone() * &column.value_fraction;
+						}
+						ballots_transferred += &cell.ballots;
+					}
 				}
+				
+				if !is_weighted {
+					votes_transferred = ballots_transferred.clone();
+				}
+				
+				// If surplus, multiply by surplus fraction
+				if let Some(n) = &surplus_numer {
+					votes_transferred *= n;
+				}
+				if let Some(n) = &surplus_denom {
+					votes_transferred /= n;
+				}
+			} else if opts.sum_surplus_transfers == SumSurplusTransfersMode::PerBallot {
+				// Sum transfer per each individual ballot
+				for column in self.columns.iter() {
+					if let Some(cell) = column.cells.get(*candidate) {
+						ballots_transferred += &cell.ballots;
+						
+						let mut new_value_fraction;
+						if is_weighted {
+							new_value_fraction = column.value_fraction.clone();
+							// If surplus, multiply by surplus fraction
+							if let Some(n) = &surplus_numer {
+								new_value_fraction *= n;
+							}
+							if let Some(n) = &surplus_denom {
+								new_value_fraction /= n;
+							}
+							// Round if required
+							if let Some(dps) = opts.round_values {
+								new_value_fraction.floor_mut(dps);
+							}
+						} else {
+							if let Some(n) = &surplus_numer {
+								new_value_fraction = n.clone();
+							} else {
+								// Transferred at original value
+								new_value_fraction = column.value_fraction.clone();
+							}
+							if let Some(n) = &surplus_denom {
+								new_value_fraction /= n;
+							}
+							// Round if required
+							if let Some(dps) = opts.round_values {
+								new_value_fraction.floor_mut(dps);
+							}
+						}
+						
+						votes_transferred += cell.ballots.clone() * new_value_fraction;
+					}
+				}
+			} else {
+				unreachable!();
 			}
 			
+			// Round if required
 			if let Some(dps) = opts.round_votes {
 				votes_transferred.floor_mut(dps);
 			}
@@ -102,23 +163,56 @@ impl<'e, N: Number> TransferTable<'e, N> {
 		}
 		
 		// Credit exhausted votes
-		let mut votes_transferred = N::new();
+		// If exclusion or not --transferable-only
-		let mut ballots_transferred = N::new();
+		if surplus.is_none() || !opts.transferable_only {
-		
+			// Standard rules
-		for column in self.columns.iter() {
+			let mut votes_transferred = N::new();
-			votes_transferred += column.exhausted.ballots.clone() * &column.value_fraction;
+			let mut ballots_transferred = N::new();
-			ballots_transferred += &column.exhausted.ballots;
+			
+			for column in self.columns.iter() {
+				if is_weighted {
+					votes_transferred += column.exhausted.ballots.clone() * &column.value_fraction;
+				}
+				ballots_transferred += &column.exhausted.ballots;
+			}
+			
+			if !is_weighted {
+				votes_transferred = ballots_transferred.clone();
+			}
+			
+			// If surplus, multiply by surplus fraction
+			if let Some(n) = &surplus_numer {
+				votes_transferred *= n;
+			}
+			if let Some(n) = &surplus_denom {
+				votes_transferred /= n;
+			}
+			
+			// Round if required
+			if let Some(dps) = opts.round_votes {
+				votes_transferred.floor_mut(dps);
+			}
+			
+			state.exhausted.transfer(&votes_transferred);
+			state.exhausted.ballot_transfers += ballots_transferred;
+			
+			checksum += votes_transferred;
+		} else {
+			// Credit only nontransferable difference
+			if surplus_numer.is_none() {
+				// TODO: Is there a purer way of calculating this?
+				let difference = surplus.unwrap().clone() - &checksum;
+				state.exhausted.transfer(&difference);
+				checksum += difference;
+				
+				for column in self.columns.iter() {
+					state.exhausted.ballot_transfers += &column.exhausted.ballots;
+				}
+			} else {
+				// No ballots exhaust
+			}
 		}
 		
-		if let Some(dps) = opts.round_votes {
-			votes_transferred.floor_mut(dps);
-		}
-		
-		state.exhausted.transfer(&votes_transferred);
-		state.exhausted.ballot_transfers += ballots_transferred;
-		
-		checksum += votes_transferred;
-		
 		return checksum;
 	}
 }