diff --git a/docs/options.md b/docs/options.md index 3c81fad..fb0bce8 100644 --- a/docs/options.md +++ b/docs/options.md @@ -20,7 +20,7 @@ The preset dropdown allows you to choose from a hardcoded list of preloaded STV | [Wright STV](https://www.aph.gov.au/Parliamentary_Business/Committees/House_of_Representatives_Committees?url=em/elect07/subs/sub051.1.pdf) | Rules proposed by Anthony van der Craats designed for computer counting, involving reset and re-iteration of the count after each candidate exclusion. | | ✓ | | [PRSA 1977](https://www.prsa.org.au/rule1977.htm) | Simple rules designed for hand counting, using the exclusive Gregory method, with counting performed in thousandths of a vote. | | ✓ | | [ERS97](https://www.electoral-reform.org.uk/latest-news-and-research/publications/how-to-conduct-an-election-by-the-single-transferable-vote-3rd-edition/) | More complex rules designed for hand counting, using the exclusive Gregory method. | | ✓ | -| • ERS76 | Former rules from the 1976 2nd edition. | [E6] | | +| • ERS76 | Former rules from the 1976 2nd edition. | [E6] | ✓ | | • ERS73 | Former rules from the 1973 1st edition. | [E6] | | | Church of England | Rules from the Church of England [*Single Transferable Vote Rules 2020*](https://www.churchofengland.org/sites/default/files/2020-02/STV%20Rules%202020%20-%20final.pdf), similar to ERS73. | | @@ -31,7 +31,7 @@ Exceptions: * [E3] A tie between 2 candidates for the final vacancy will be broken backwards then at random, rather than the method described in the legislation. * [E4] Bulk exclusion is not performed. See the section on *Bulk exclusion* for further discussion. * [E5] The ‘mathematically eliminated by the sum of all ranked-choice votes comparison’ is not implemented. -* [E6] The quota is always calculated to 2 decimal places. For full ERS76 (ERS73) compliance, set *Round quota to 0 d.p.* when the quota is more than 100 (100 or more). +* [E6] By default, the quota is always calculated to 2 decimal places. For full ERS76 (ERS73) compliance, set *Round quota to 0 d.p.* when the quota is more than 100 (100 or more). For details of validation, see [validation.md](validation.md). diff --git a/docs/validation.md b/docs/validation.md index 94e1baf..10c3832 100644 --- a/docs/validation.md +++ b/docs/validation.md @@ -18,6 +18,7 @@ STV-counting software is frequently validated empirically by comparing the resul | PRSA 1977 | [*Proportional Representation Manual*](https://www.prsa.org.au/publicat.htm#p2) [example 1](https://www.prsa.org.au/utopiatc.pdf) | [Model result](https://www.prsa.org.au/example1.pdf) (official) | ✓ | | ERS97 | [Reverse engineered ballot papers for the ERS97 model election](https://yingtongli.me/blog/2021/01/04/ers97.html) | [Model result](https://www.electoral-reform.org.uk/latest-news-and-research/publications/how-to-conduct-an-election-by-the-single-transferable-vote-3rd-edition/#sub-section-24) (official) | ✓ | | ERS97 | [Joe Otten/eSTV ballot papers for the ERS97 model election](https://web.archive.org/web/20020606014623/http://estv.otten.co.uk/) | [Model result](https://www.electoral-reform.org.uk/latest-news-and-research/publications/how-to-conduct-an-election-by-the-single-transferable-vote-3rd-edition/#sub-section-24) (official) | ✓ | +| ERS76 | Ballot papers adapted from Joe Otten/eSTV ERS97 papers | Model result (official) | ✓ | # References diff --git a/src/stv/mod.rs b/src/stv/mod.rs index 83298cc..60ddf91 100644 --- a/src/stv/mod.rs +++ b/src/stv/mod.rs @@ -785,8 +785,14 @@ fn total_to_quota(mut total: N, seats: usize, opts: &STVOptions) -> N return total; } -/// Update vote required for election according to ERS97 rules +/// Update vote required for election according to ERS97/ERS76 rules fn update_vre(state: &mut CountState, opts: &STVOptions) { + if opts.quota_mode == QuotaMode::ERS76 && state.num_excluded == 0 && (state.num_elected == 0 || state.candidates.values().all(|cc| !cc.finalised)) { + // ERS76 rules: Do not update VRE until a surplus is distributed or candidate is excluded + state.vote_required_election = state.quota.clone(); + return; + } + let mut log = String::new(); // Calculate active vote @@ -1023,8 +1029,11 @@ fn elect_hopefuls<'a, N: Number>(state: &mut CountState<'a, N>, opts: &STVOption count_card.state = CandidateState::Elected; state.num_elected += 1; count_card.order_elected = state.num_elected as isize; + + let elected_on_quota; if cmp_quota_criterion(state.quota.as_ref().unwrap(), count_card, opts) { // Elected with a quota + elected_on_quota = true; state.logger.log_smart( "{} meets the quota and is elected.", "{} meet the quota and are elected.", @@ -1032,6 +1041,7 @@ fn elect_hopefuls<'a, N: Number>(state: &mut CountState<'a, N>, opts: &STVOption ); } else { // Elected with vote required + elected_on_quota = false; state.logger.log_smart( "{} meets the vote required and is elected.", "{} meet the vote required and are elected.", @@ -1051,9 +1061,10 @@ fn elect_hopefuls<'a, N: Number>(state: &mut CountState<'a, N>, opts: &STVOption cands_meeting_quota.remove(cands_meeting_quota.iter().position(|c| *c == candidate).unwrap()); } - if opts.quota_mode == QuotaMode::ERS97 { + if opts.quota_mode == QuotaMode::ERS97 || (opts.quota_mode == QuotaMode::ERS76 && elected_on_quota) { // Vote required for election may have changed - // This is not performed in ERS76 - TODO: Check this + // ERS97: Check this after every elected candidate (cf. model election) + // ERS76: Check this after every candidate elected on a quota, but all at once for candidates elected on VRE (cf. model election) calculate_quota(state, opts); // Repeat in case vote required for election has changed diff --git a/tests/data/.~lock.ers76.ods# b/tests/data/.~lock.ers76.ods# new file mode 100644 index 0000000..b30e851 --- /dev/null +++ b/tests/data/.~lock.ers76.ods# @@ -0,0 +1 @@ +Yingtong Li,runassudo,NEXUS.localdomain,09.08.2021 19:43,file:///home/runassudo/.config/libreoffice/4; \ No newline at end of file diff --git a/tests/data/ers76.blt b/tests/data/ers76.blt new file mode 100644 index 0000000..12d97c3 --- /dev/null +++ b/tests/data/ers76.blt @@ -0,0 +1,71 @@ +# Comment: Ballot papers for the ERS76 model election - all votes - ERS76 +# Source: Adapted by RunasSudo from ers97.blt (Joe Otten) +# Contributor: RunasSudo +11 6 +8 1 2 0 +3 1 3 0 +14 1 4 0 +34 1 5 0 +1 1 2 0 # Changed from "1 6" +4 1 7 0 +1 1 8 0 +3 1 9 3 0 # One of these changed to "1 9 6" +3 1 9 4 0 +3 1 9 6 0 +3 1 9 7 0 +4 1 9 8 0 +9 1 9 0 +4 1 10 3 0 +5 1 10 4 0 +3 1 10 6 0 +3 1 10 7 0 +6 1 10 8 0 +10 1 10 0 +1 1 11 5 0 +1 1 11 0 +11 1 0 +105 2 0 +91 3 0 +90 4 0 +81 5 0 +64 6 0 +11 7 6 0 +36 7 8 0 +12 7 0 +55 8 0 +3 9 3 0 +2 9 4 0 +2 9 5 3 0 +1 9 5 4 0 +15 9 5 0 +2 9 6 0 +2 9 8 0 +2 10 3 0 +2 10 4 0 +2 10 5 6 0 +1 10 5 7 6 0 +2 10 5 8 0 +11 10 5 0 +1 10 6 0 +1 10 7 4 0 +1 10 8 0 +1 10 0 +2 11 2 0 +4 11 3 0 +1 11 4 0 +5 11 7 8 0 +10 11 8 0 +1 11 0 +0 +"Smith" +"Duke" +"Prince" +"Freeman" +"Carpenter" +"Baron" +"Abbot" +"Vicar" +"Wright" +"Glazier" +"Monk" +"ERS Model - 1997 Edition" diff --git a/tests/data/ers76.csv b/tests/data/ers76.csv new file mode 100644 index 0000000..099c286 --- /dev/null +++ b/tests/data/ers76.csv @@ -0,0 +1,15 @@ +Stage:,1,,2,,4,,6,,7,,8, +Comment:,First preferences,,Surplus of Smith,,Exclusion of Monk,,"Exclusion of Glazier, Wright",,Surplus of Carpenter,,Exclusion of Abbot, +Smith,134,EL,108,EL,108,EL,108,EL,108,EL,108,EL +Duke,105,H,106.89,H,108.89,EL,108.89,EL,108.89,EL,108.89,EL +Prince,91,H,91.63,H,95.63,H,102.1,H,104.1,EL,104.1,EL +Freeman,90,H,92.94,H,93.94,H,99.62,H,100.62,H,101.62,EL +Carpenter,81,H,88.14,H,88.35,H,122.35,EL,108,EL,108,EL +Baron,64,H,64,H,64,H,68.26,H,70.26,H,82.26,H +Abbot,59,H,59.84,H,64.84,H,67.1,H,68.1,H,2.1,EX +Vicar,55,H,55.21,H,65.21,H,70.31,H,72.31,H,113.31,EL +Wright,27,H,32.25,H,32.25,H,0,EX,0,EX,0,EX +Glazier,24,H,30.51,H,30.51,H,0,EX,0,EX,0,EX +Monk,23,H,23.42,H,0,EX,0,EX,0,EX,0,EX +Non-transferable,0,,0.17,,1.38,,6.37,,12.72,,24.72, +Votes required,108,,,,,,,,104.07,,96.09, diff --git a/tests/data/ers76.ods b/tests/data/ers76.ods new file mode 100644 index 0000000..c6cecec Binary files /dev/null and b/tests/data/ers76.ods differ diff --git a/tests/ers97.rs b/tests/ers.rs similarity index 76% rename from tests/ers97.rs rename to tests/ers.rs index 57f48dc..5f5a8fd 100644 --- a/tests/ers97.rs +++ b/tests/ers.rs @@ -61,3 +61,24 @@ fn ers97_rational() { utils::read_validate_election::("tests/data/ers97.csv", "tests/data/ers97.blt", stv_opts, None, &["nt", "vre"]); } + +#[test] +fn ers76_rational() { + let stv_opts = stv::STVOptionsBuilder::default() + .round_surplus_fractions(Some(2)) + .round_values(Some(2)) + .round_votes(Some(2)) + .round_quota(Some(0)) + .quota(stv::QuotaType::DroopExact) + .quota_criterion(stv::QuotaCriterion::GreaterOrEqual) + .quota_mode(stv::QuotaMode::ERS76) + .surplus(stv::SurplusMethod::EG) + .transferable_only(true) + .exclusion(stv::ExclusionMethod::ByValue) + .early_bulk_elect(false) + .bulk_exclude(true) + .defer_surpluses(true) + .build().unwrap(); + + utils::read_validate_election::("tests/data/ers76.csv", "tests/data/ers76.blt", stv_opts, None, &["nt", "vre"]); +}