Main Author: Julien Boudry
License: MIT - Please say hello if you like or use this code!
Contribute: Contribute File
Donation: ₿ 1LhZZVxmNCTPWftKFTUKbRiUKzA67RPWez You can also offer me a bottle of good wine.
Methods provided natively: Condorcet / Borda (+ Nauru variant) / Copeland / Dodgson (2 Approximations) / FTPT / Instant-runoff (alternative vote) / Kemeny–Young / Minimax (+ variants) / Ranked Pairs (+ variants) / Schulze (+ variants)
A PHP library implementing the Condorcet voting system and others methods like the Schulze method. And also a powerful election manager.
- Project State and Specifications
- Main features
- Supported Methods
a. Methods provided natively
b. Add your own method
- How to use it?
b. Condorcet Wiki Manual
c. Class & Methods reference
d. Examples Have a look on Examples!
e. Really quick and simple example
- Performance & Coding style considerations
- Roadmap for further releases
- Related projects / They use Condorcet
Project State and Specifications
- Stable Version: 1.8.x
- PHP Requirement: PHP 7.1 with Ctype, MB_String, Json common extensions. (tested up to PHP 7.3)
- Old Stable : 1.0.x support provided
- PHP Requirement: PHP 5.6 with Ctype, MB_String, Json common extensions. (tested up to PHP 7.1)
v0.9x series is no longer supported. But bug report are welcomes, code base can be close to v1.x series.
Some support and fix can be done for 0.14 version on demand. Since v0.90, you should consider than it's a new project (api, engine).
- Manage an election
- Respect an election cycle: Registering candidate, registering vote, get results from many algorithms.
- Ordered votes, delete it, simulate partials results.
- Many input type available (String, Json, Parse text, Objects...)
- Integrity check (checksumming) and logs.
- Support for storing elections (serializing Election object, exports datas...)
- Some methods can be use nearly front final user (anti-spam check, parsing input, human friendly results and stats, vote constraints...)
- Get election results and stats
- Get the natural Condorcet Winner, Loser, Pairwise, Paradox...
- Get full ranking from advanced methods (Schulze, Copeland, Ranked Pairs, Kemeny–Young, Minimax...)
- Get some additional stats from these methods
- Force ranking all candidate implicitly (default) or allow voters to not rank all candidates.
- Put weight for each vote, give more importance to certain voters.
- Be more powerful
- All are objects, all are abstract (But there is many higher level functions and inputs types).
- Candidates and Votes are objects which can take part to multiples elections on the same time and change her name or ranking dynamically. That allow powerful tools to simulate elections.
- Manage hundreds of billions votes by activating an external driver to store (instead of RAM) an unlimited number of votes during the computation phase. A PDO driver is provided by default, an example is provided with SQLite, an interface allows you to design others drivers.
- Extend it! Configure it!
- Modular architecture allow you to registered additional methods of Condorcet (or not Condorcet) without fork Condorcet PHP! Just make your own module on your own namespace.
- Candidate and Vote class are extensible.
- Allow you to use your own datastore driver to manage very large elections at your way.
- Many configurations options and methods.
Condorcet PHP is not designed for high performances. But can handle virtually unlimited voting without limit or degrading performance
And has no certification or proven implementation that would guarantee a very high level of reliability.
Methods provided natively
- Condorcet Basic Give you the natural winner or loser of Condorcet, if there is one.
- Borda count https://en.wikipedia.org/wiki/Borda_count
- Borda System (starting at 1)
- Dowdall system (Nauru)
- Copeland http://en.wikipedia.org/wiki/Copeland%27s_method
- Dodgson Approximations (Not the real Dodgson method, see: Lewis Caroll, Voting and the taxicab metric)
- Dodgson Quick (recommended)
- Dodgson Tideman approximation
- First-past-the-post https://en.wikipedia.org/wiki/First-past-the-post_voting
- Instant-runoff (Alternative Vote / Preferential Voting) https://en.wikipedia.org/wiki/Instant-runoff_voting
- Kemeny–Young http://en.wikipedia.org/wiki/Kemeny-Young_method Kemeny-Young is currently limited up to 8 candidats. Note that, for 8 candidates, you must provide into php.ini a memory_limit upper than 160MB.
- Minimax Family http://en.wikipedia.org/wiki/Minimax_Condorcet
- Minimax Winning
- Minimax Margin
- Minimax Opposition
- Ranked Pairs Family (Tideman method) https://en.wikipedia.org/wiki/Ranked_pairs
- Ranked Pairs Margin Margin variant is recommended by Nicolaus Tideman himself.
- Ranked Pairs Winning Widely used variant, maybe more than the original.
- Schulze Method http://en.wikipedia.org/wiki/Schulze_method
- Schulze Winning Schulze Winning is recommended by Markus Schulze himself.
- Schulze Margin Variant from Markus Schulze himself.
- Schulze Ratio Variant from Markus Schulze himself.
Add your own method as module
Condorcet is designed to be easily extensible with new algorithms (they don't need share the same namespace). A modular schematic is already used for all algorithms provided, so you can easily help, do not forget to make a pull request!
More explanations in the documentation below
How to use it?
I have undertaken and continues to undertake efforts to reform and improve the documentation. Thereof is not yet satisfactory and perfectly updated. Your help is welcome!
This project is consistent with the standard PSR-4 and can be loaded easily and without modification in most frameworks or Composer autoloader. Namespace \Condorcet is used. The examples also provide an easy way of implementation using an optional Condorcet autoloader. If you don't want to use composer or PSR-4 autoloader.
Condorcet Wiki Manual
Living and learning examples, giving an overview but not exhaustive of the possibilities of the library.
Class & Methods reference
The precise documentation of methods is not a wiki. It can be found in the form of Markdown in the "Documentation" folder for each release.
- Non-visual quick tour of opportunities without interface (not exhaustive and partial, but just a great tour.)
With html output basics examples
- Condorcet Wiki Manual provide many code example
- Manage millions of votes with an external database drive Your own driver, or the provided simple driver for PDO.
Really quick and simple example
OK: sacrifice to the local tradition of lazy.
use Condorcet\Condorcet; use Condorcet\Election; use Condorcet\Candidate; use Condorcet\CondorcetUtil; use Condorcet\Vote; $myElection1 = new Election () ; // Create your own candidate object $candidate1 = new Candidate ('Candidate 1'); $candidate2 = new Candidate ('Candidate 2'); $candidate3 = new Candidate ('Candidate 3'); // Register your candidates $myElection1->addCandidate($candidate1); $myElection1->addCandidate($candidate2); $myElection1->addCandidate($candidate3); $candidate4 = $myElection1->addCandidate('Candidate 4'); // Add some votes, by some ways $myElection1->addVote( array( $candidate2, // 1 [$candidate1, $candidate4] // 2 - Tie // Last rank is optionnal. Here it's : $candidate3 )); $myElection1->addVote('Candidate 2 > Candidate 3 > Candidate 4 = Candidate 1'); // last rank can also be omitted $myElection1->parseVotes( 'tagX || Candidate 1 > Candidate 2 = Candidate 4 > Candidate 3 * 4 tagX, tagY || Candidate 3 > Candidate 1 * 3' ); // Powerfull, it add 7 votes $myElection1->addVote( new Vote ( array( $candidate4, $candidate2 // You can ignore the over. They will be at the last rank in the contexte of each election. ) )); // Get Result // Natural Condorcet Winner $myWinner = $myElection1->getWinner(); // Return a candidate object echo 'My winner is ' . $myWinner->getName() . '<br>' ; // Natural Condorcet Loser $myLoser = $myElection1->getLoser(); // Return a candidate object echo 'My loser is ' . $myLoser->getName() ; // Schulze Ranking $myResultBySchulze = $myElection1->getResult('Schulze'); // Return a multi-dimensional array, filled with objects Candidate (multi-dimensional if tie on a rank) # Echo it easily CondorcetUtil::format($myResultBySchulze); // Get Schulze advanced computing data & stats $mySchulzeStats = $myElection1->getResult('Schulze')->getStats(); // Get Copeland Ranking $myResultByCopeland = $myElection1->getResult('Copeland'); // Get Pairwise $myPairwise = $myElection1->getPairwise(); // How long computation time behind us? $timer = $myElection1->getGlobalTimer(); // SHA-2 checksum and sleep $myChecksum = $myElection1->getChecksum(); $toStore = serialize($myElection1); // You can now unset your $candidate1 & co. On wake up, Condorcet election will build distinct with new reference. # And many many more than that. Read the doc. & look advanced examples.
Performance & Coding style considerations
The code is very close to the respect of PSR-1 (lacks only the naming of methods), and freely influenced by PSR-2 when it is not unnecessarily authoritarian.
- Complex use case with three algorithms chained (Natural Condorcet, Schulze, Copeland), multiple elections sharing votes & candidates and hundreds of votes.
- Memory usage: less than 2M
- Execution time: less than 30ms
- use Kemeny-Young 6 candidates: 5MB - 150ms
- use Kemeny-Young 7 candidates: 32MB - 600ms
- use Kemeny-Young 8 candidates: 135MB - 2500ms
Massive election case:
Extending PHP memory_limit allows you to manage hundreds of thousands of votes, but it can be a bit slower than outsource this data (PHP don't like that) and it's not extensive to infinity.
If you need to manage election with more than 50 000 votes. You should consider externalize your data, Condorcet provide a simple PDO driver to store data outside RAM between processing steps, this driver store it into classical relational database system, it's support hundreds millions votes (or more). You can too develop your own datastore driver (to store into NoSQL... all yours fantasy), the modular architecture allows you to link it easily.
Benchmark on a modern machine (linux - x64 - php 7.0 - cli).
Roadmap for further releases
- Better cache system to prevent any full computing of the Pairwise on new vote / remove vote. This would remain a minor optimization that does not concern all cases of use.
- Rebuild Exception System
- Research reference librarians !!
Related projects / They use Condorcet
- From August 2014: Condorcet.Vote Web services to create and store online Condorcet election. Including interactives and collaborative features.
It is based in large part on this project, and uses the library as a real election manager for computing, storage & stats.
(French interface) Web wrapper to compute and show result for classical music blind challenge with the Condorcet Class full potential (can also be used and adapted for any elections).
Look like the examples provided here, but better: Gustav Mahler blind listening test