relative-placement.js
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/**
* Created by Techniv on 30/11/2016.
* @module relativePlacement
*/
(function (definition) {
// Node export
if(typeof global != 'undefined' && typeof module != 'undefined' && module.exports) return module.exports = definition();
//Browser export
if(typeof window != 'undefined'){
if(typeof angular != 'undefined' && angular.version.major == 1) return angular.module('relative-placement-js').factory('RelativePlacement', definition);
if(typeof requirejs != 'undefined') return define(definition());
window.RelativePlacement = definition();
}
})(function(){
/**
* @name RelativePlacement
* @constructor
* @property {Candidate[]} candidateList
* @property {String[][]} votes
* @property {Number} numberOfCandidates
*
*/
function RelativePlacement() {
Object.defineProperties(this, {
candidateList: {value: {}},
votes: {value: []},
numberOfCandidates: {get: () => Object.keys(this.candidateList).length}
});
}
RelativePlacement.version = '0.0.0';
/**
* @name addCandidate
* @param {String} candidateName
* @methodOf RelativePlacement
* @this RelativePlacement
*/
RelativePlacement.prototype.addCandidate = function addCandidate(candidateName){
if(this.votes.length) throw new Error("Adding candidates after votes is not permit.");
if(this.candidateList[candidateName]) throw new Error('"' +candidateName+ '" already exist in candidate list.');
this.candidateList[candidateName] = new Candidate(candidateName);
};
/**
* @name addCandidates
* @param {String[]} candidateNames
* @methodOf RelativePlacement
* @this RelativePlacement
*/
RelativePlacement.prototype.addCandidates = function (candidateNames) {
for(let i = 0; i < candidateNames.length; i++){
this.addCandidate(candidateNames[i]);
}
};
/**
* @name addVote
* @param {String[]} vote
* @methodOf RelativePlacement
* @this RelativePlacement
*/
RelativePlacement.prototype.addVote = function (vote) {
if(vote.length != this.numberOfCandidates)
throw new Error('The vote and the candidate list have not the same size.');
var candidates = Object.keys(this.candidateList);
var controlMask = Math.pow(2,candidates.length)-1;
var checkMask = 0;
for(let i = 0; i < vote.length; i++){
var index = candidates.indexOf(vote[i]);
if(index == -1) throw new Error('The candidate "'+vote[i]+"' is not present in candidate list.");
checkMask |= Math.pow(2, index);
}
if(checkMask != controlMask) throw new Error('Candidate must be unique in each vote.');
this.votes.push(vote);
for(let i = 0; i < vote.length; i++){
let candidate = this.candidateList[vote[i]];
candidate.votes.push(i);
}
};
/**
*
* @param {String[][]} votes
*/
RelativePlacement.prototype.addVotes = function (votes) {
votes.forEach(vote => this.addVote(vote));
};
RelativePlacement.prototype.getResult = function () {
return relativePlacement(this.votes, this.candidateList);
};
/**
*
* @param {String} name
* @constructor
* @property {String} name
* @property {Number[]} votes
* @property {Number[]} placements
* @property {Number[]} cumulativePlacement
*/
function Candidate(name) {
Object.defineProperties(this, {
name: {value: name, enumerable: true},
votes: {value:[], enumerable: true},
placements: {value:[], enumerable: true, writable: true},
cumulativePlacement: {value:[], enumerable: true, writable: true}
});
}
/**
* @name relativePlacement
* @memberOf RelativePlacement
* @static
* @param {String[][]} votes
* @param {Object<String,Candidate>} [candidates]
* @returns {String[]}
*/
function relativePlacement(votes, candidates){
if(votes.length <= 1) return votes[0];
// Prepare candidate list if not pass
var init = false, majority, result, candidateNames;
if(!candidates) {
candidates = {};
init = true;
}
candidateNames = votes[0];
majority = Math.floor(votes.length / 2) + 1;
result = [];
candidateNames.forEach((name) => {
if(init) candidates[name] = new Candidate(name);
candidates[name].placements[candidateNames.length-1] = 0;
candidates[name].placements.fill(0,0,candidateNames.length-1);
candidates[name].cumulativePlacement[candidateNames.length-1] = 0;
candidates[name].cumulativePlacement.fill(0,0,candidateNames.length-1);
});
// Assign votes
votes.forEach((vote,num) => {
vote.forEach((name, place) => {
var candidate = candidates[name];
candidate.votes[num] = place;
for(let i = place; i < candidate.placements.length; i++){
candidate.placements[i]++;
candidate.cumulativePlacement[i] += place + 1;
}
});
});
// Search placement
var cursor = 0, nextPlace = 0, proposed = [];
while(result.length < candidateNames.length && cursor < candidateNames.length){
// Search majority
candidateNames.forEach(name => {
if(result.indexOf(name) != -1) return;
var candidate = candidates[name];
if(candidate.placements[cursor] >= majority) proposed.push(candidate);
});
if(proposed.length){
proposed.sort((a,b) => {
var sortCursor = cursor;
while(sortCursor < candidateNames.length){
if(a.placements[sortCursor] != b.placements[sortCursor])
return b.placements[sortCursor] - a.placements[sortCursor];
if(a.cumulativePlacement[sortCursor] != b.cumulativePlacement[sortCursor])
return a.cumulativePlacement[sortCursor] - b.cumulativePlacement[sortCursor];
sortCursor++;
}
return 0;
});
result = result.concat(proposed.map(candidate => candidate.name));
proposed.splice(0);
continue;
}
cursor++;
}
return result;
}
RelativePlacement.relativePlacement = relativePlacement;
return RelativePlacement;
});