OpenTally/src/main.rs

393 lines
13 KiB
Rust

/* OpenTally: Open-source election vote counting
* Copyright © 2021 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/>.
*/
use opentally::constraints::Constraints;
use opentally::election::{CandidateState, CountState, Election};
use opentally::numbers::{Fixed, GuardedFixed, NativeFloat64, Number, Rational};
use opentally::stv::{self, STVOptions};
use opentally::ties;
use clap::{AppSettings, Clap};
use std::cmp::max;
use std::fs::File;
use std::io::{self, BufRead};
use std::ops;
/// Open-source election vote counting
#[derive(Clap)]
#[clap(name="OpenTally", version=opentally::VERSION)]
struct Opts {
#[clap(subcommand)]
command: Command,
}
#[derive(Clap)]
enum Command {
STV(STV),
}
/// Count a single transferable vote (STV) election
#[derive(Clap)]
#[clap(setting=AppSettings::DeriveDisplayOrder)]
struct STV {
// ----------------
// -- File input --
/// Path to the BLT file to be counted
filename: String,
// ----------------------
// -- Numbers settings --
/// Numbers mode
#[clap(help_heading=Some("NUMBERS"), short, long, possible_values=&["rational", "fixed", "gfixed", "float64"], default_value="rational", value_name="mode")]
numbers: String,
/// Decimal places if --numbers fixed
#[clap(help_heading=Some("NUMBERS"), long, default_value="5", value_name="dps")]
decimals: usize,
/// Convert ballots with value >1 to multiple ballots of value 1
#[clap(help_heading=Some("NUMBERS"), long)]
normalise_ballots: bool,
// -----------------------
// -- Rounding settings --
/// Round surplus fractions to specified decimal places
#[clap(help_heading=Some("ROUNDING"), long, alias="round-tvs", value_name="dps")]
round_surplus_fractions: Option<usize>,
/// Round ballot values to specified decimal places
#[clap(help_heading=Some("ROUNDING"), long, alias="round-weights", value_name="dps")]
round_values: Option<usize>,
/// Round votes to specified decimal places
#[clap(help_heading=Some("ROUNDING"), long, value_name="dps")]
round_votes: Option<usize>,
/// Round quota to specified decimal places
#[clap(help_heading=Some("ROUNDING"), long, value_name="dps")]
round_quota: Option<usize>,
/// (Gregory STV) How to calculate votes to credit to candidates in surplus transfers
#[clap(help_heading=Some("ROUNDING"), long, possible_values=&["single_step", "by_value", "per_ballot"], default_value="single_step", value_name="mode")]
sum_surplus_transfers: String,
/// (Meek STV) Limit for stopping iteration of surplus distribution
#[clap(help_heading=Some("ROUNDING"), long, default_value="0.001%", value_name="tolerance")]
meek_surplus_tolerance: String,
// -----------
// -- Quota --
/// Quota type
#[clap(help_heading=Some("QUOTA"), short, long, possible_values=&["droop", "hare", "droop_exact", "hare_exact"], default_value="droop_exact")]
quota: String,
/// Whether to elect candidates on meeting (geq) or strictly exceeding (gt) the quota
#[clap(help_heading=Some("QUOTA"), short='c', long, possible_values=&["geq", "gt"], default_value="gt", value_name="criterion")]
quota_criterion: String,
/// Whether to apply a form of progressive quota
#[clap(help_heading=Some("QUOTA"), long, possible_values=&["static", "ers97", "ers76"], default_value="static", value_name="mode")]
quota_mode: String,
// ------------------
// -- STV variants --
/// Tie-breaking method
#[clap(help_heading=Some("STV VARIANTS"), short='t', long, possible_values=&["forwards", "backwards", "random", "prompt"], default_value="prompt", value_name="methods")]
ties: Vec<String>,
/// Random seed to use with --ties random
#[clap(help_heading=Some("STV VARIANTS"), long, value_name="seed")]
random_seed: Option<String>,
/// Method of surplus distributions
#[clap(help_heading=Some("STV VARIANTS"), short='s', long, possible_values=&["wig", "uig", "eg", "meek", "cincinnati", "hare"], default_value="wig", value_name="method")]
surplus: String,
/// (Gregory STV) Order to distribute surpluses
#[clap(help_heading=Some("STV VARIANTS"), long, possible_values=&["by_size", "by_order"], default_value="by_size", value_name="order")]
surplus_order: String,
/// (Gregory STV) Examine only transferable papers during surplus distributions
#[clap(help_heading=Some("STV VARIANTS"), long)]
transferable_only: bool,
/// (Gregory STV) Method of exclusions
#[clap(help_heading=Some("STV VARIANTS"), long, possible_values=&["single_stage", "by_value", "by_source", "parcels_by_order", "wright"], default_value="single_stage", value_name="method")]
exclusion: String,
/// (Meek STV) NZ Meek STV behaviour: Iterate keep values one round before candidate exclusion
#[clap(help_heading=Some("STV VARIANTS"), long)]
meek_nz_exclusion: bool,
/// (Cincinnati/Hare) Method of drawing a sample
#[clap(help_heading=Some("STV VARIANTS"), long, possible_values=&["stratified", "by_order", "nth_ballot"], default_value="stratified", value_name="method")]
sample: String,
/// (Cincinnati/Hare) Sample-based methods: Check for candidate election after each individual ballot paper transfer
#[clap(help_heading=Some("STV VARIANTS"), long)]
sample_per_ballot: bool,
// -------------------------
// -- Count optimisations --
/// Continue count even if continuing candidates fill all remaining vacancies
#[clap(help_heading=Some("COUNT OPTIMISATIONS"), long)]
no_early_bulk_elect: bool,
/// Use bulk exclusion
#[clap(help_heading=Some("COUNT OPTIMISATIONS"), long)]
bulk_exclude: bool,
/// Defer surplus distributions if possible
#[clap(help_heading=Some("COUNT OPTIMISATIONS"), long)]
defer_surpluses: bool,
/// Elect candidates only when their surpluses are distributed; (Meek STV) Wait for keep values to converge before electing candidates
#[clap(help_heading=Some("COUNT OPTIMISATIONS"), long)]
no_immediate_elect: bool,
/// On exclusion, exclude any candidate with fewer than this many votes
#[clap(help_heading=Some("COUNT OPTIMISATIONS"), long, default_value="0", value_name="votes")]
min_threshold: String,
// -----------------
// -- Constraints --
/// Path to a CON file specifying constraints
#[clap(help_heading=Some("CONSTRAINTS"), long)]
constraints: Option<String>,
/// Mode of handling constraints
#[clap(help_heading=Some("CONSTRAINTS"), long, possible_values=&["guard_doom"], default_value="guard_doom")]
constraint_mode: String,
// ----------------------
// -- Display settings --
/// Hide excluded candidates from results report
#[clap(help_heading=Some("DISPLAY"), long)]
hide_excluded: bool,
/// Sort candidates by votes in results report
#[clap(help_heading=Some("DISPLAY"), long)]
sort_votes: bool,
/// Print votes to specified decimal places in results report
#[clap(help_heading=Some("DISPLAY"), long, default_value="2", value_name="dps")]
pp_decimals: usize,
}
fn main() {
match main_() {
Ok(_) => {}
Err(code) => {
std::process::exit(code);
}
}
}
fn main_() -> Result<(), i32> {
// Read arguments
let opts: Opts = Opts::parse();
let Command::STV(cmd_opts) = opts.command;
// Read and count election according to --numbers
if cmd_opts.numbers == "rational" {
let mut election = election_from_file(&cmd_opts.filename)?;
maybe_load_constraints(&mut election, &cmd_opts.constraints);
// Must specify ::<N> here and in a few other places because ndarray causes E0275 otherwise
count_election::<Rational>(election, cmd_opts)?;
} else if cmd_opts.numbers == "float64" {
let mut election = election_from_file(&cmd_opts.filename)?;
maybe_load_constraints(&mut election, &cmd_opts.constraints);
count_election::<NativeFloat64>(election, cmd_opts)?;
} else if cmd_opts.numbers == "fixed" {
Fixed::set_dps(cmd_opts.decimals);
let mut election = election_from_file(&cmd_opts.filename)?;
maybe_load_constraints(&mut election, &cmd_opts.constraints);
count_election::<Fixed>(election, cmd_opts)?;
} else if cmd_opts.numbers == "gfixed" {
GuardedFixed::set_dps(cmd_opts.decimals);
let mut election = election_from_file(&cmd_opts.filename)?;
maybe_load_constraints(&mut election, &cmd_opts.constraints);
count_election::<GuardedFixed>(election, cmd_opts)?;
}
return Ok(());
}
fn election_from_file<N: Number>(path: &str) -> Result<Election<N>, i32> {
match Election::from_file(path) {
Ok(e) => return Ok(e),
Err(err) => {
println!("Syntax Error: {}", err);
return Err(1);
}
}
}
fn maybe_load_constraints<N: Number>(election: &mut Election<N>, constraints: &Option<String>) {
if let Some(c) = constraints {
let file = File::open(c).expect("IO Error");
let lines = io::BufReader::new(file).lines();
election.constraints = Some(Constraints::from_con(lines.map(|r| r.expect("IO Error").to_string()).into_iter()));
}
}
fn count_election<N: Number>(mut election: Election<N>, cmd_opts: STV) -> Result<(), i32>
where
for<'r> &'r N: ops::Sub<&'r N, Output=N>,
for<'r> &'r N: ops::Mul<&'r N, Output=N>,
for<'r> &'r N: ops::Div<&'r N, Output=N>,
for<'r> &'r N: ops::Neg<Output=N>
{
// Copy applicable options
let opts = STVOptions::new(
cmd_opts.round_surplus_fractions,
cmd_opts.round_values,
cmd_opts.round_votes,
cmd_opts.round_quota,
cmd_opts.sum_surplus_transfers.into(),
cmd_opts.meek_surplus_tolerance.into(),
cmd_opts.normalise_ballots,
cmd_opts.quota.into(),
cmd_opts.quota_criterion.into(),
cmd_opts.quota_mode.into(),
ties::from_strs(cmd_opts.ties, cmd_opts.random_seed),
cmd_opts.surplus.into(),
cmd_opts.surplus_order.into(),
cmd_opts.transferable_only,
cmd_opts.exclusion.into(),
cmd_opts.meek_nz_exclusion,
cmd_opts.sample.into(),
cmd_opts.sample_per_ballot,
!cmd_opts.no_early_bulk_elect,
cmd_opts.bulk_exclude,
cmd_opts.defer_surpluses,
!cmd_opts.no_immediate_elect,
cmd_opts.min_threshold,
cmd_opts.constraints,
cmd_opts.constraint_mode.into(),
cmd_opts.hide_excluded,
cmd_opts.sort_votes,
cmd_opts.pp_decimals,
);
// Validate options
match opts.validate() {
Ok(_) => {}
Err(err) => {
println!("Error: {}", err.describe());
return Err(1);
}
}
// Describe count
let total_ballots = election.ballots.iter().fold(N::zero(), |acc, b| { acc + &b.orig_value });
print!("Count computed by OpenTally (revision {}). Read {:.0} ballots from \"{}\" for election \"{}\". There are {} candidates for {} vacancies. ", opentally::VERSION, total_ballots, cmd_opts.filename, election.name, election.candidates.len(), election.seats);
let opts_str = opts.describe::<N>();
if opts_str.len() > 0 {
println!("Counting using options \"{}\".", opts_str);
} else {
println!("Counting using default options.");
}
println!();
// Normalise ballots if requested
if cmd_opts.normalise_ballots {
election.normalise_ballots();
}
// Initialise count state
let mut state = CountState::new(&election);
// Distribute first preferences
match stv::count_init(&mut state, &opts) {
Ok(_) => {}
Err(err) => {
println!("Error: {}", err.describe());
return Err(1);
}
}
let mut stage_num = 1;
print_stage(stage_num, &state, &opts);
loop {
match stv::count_one_stage(&mut state, &opts) {
Ok(is_done) => {
if is_done {
break;
}
}
Err(err) => {
println!("Error: {}", err.describe());
return Err(1);
}
}
stage_num += 1;
print_stage(stage_num, &state, &opts);
}
println!("Count complete. The winning candidates are, in order of election:");
let mut winners = Vec::new();
for (candidate, count_card) in state.candidates.iter() {
if count_card.state == CandidateState::Elected {
winners.push((candidate, count_card));
}
}
winners.sort_unstable_by(|a, b| a.1.order_elected.cmp(&b.1.order_elected));
for (i, (winner, count_card)) in winners.into_iter().enumerate() {
if let Some(kv) = &count_card.keep_value {
println!("{}. {} (kv = {:.dps2$})", i + 1, winner.name, kv, dps2=max(opts.pp_decimals, 2));
} else {
println!("{}. {}", i + 1, winner.name);
}
}
return Ok(());
}
fn print_stage<N: Number>(stage_num: usize, state: &CountState<N>, opts: &STVOptions) {
// Print stage details
match state.kind {
None => { println!("{}. {}", stage_num, state.title); }
Some(kind) => { println!("{}. {} {}", stage_num, kind, state.title); }
};
println!("{}", state.logger.render().join(" "));
// Print candidates
print!("{}", state.describe_candidates(opts));
// Print summary rows
print!("{}", state.describe_summary(opts));
println!("");
}