Rashid Khan
65 lines
1.8 KiB
JavaScript
65 lines
1.8 KiB
JavaScript
/*jshint node:true, laxcomma:true */
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"use strict";
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var debug = require('debug')('rwc');
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var RandomWeightedChoice = function (table, temperature, randomFunction, influence) {
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influence = influence || 2; // Seems fine, difficult to tune
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if (typeof(temperature)=="undefined") temperature = 50; // in [0,100], 50 is neutral
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temperature = temperature | 50;
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debug('temperature', temperature);
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var T = (temperature - 50) / 50;
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if (typeof(randomFunction)=="undefined") randomFunction = Math.random;
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var nb = table.length;
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if(!nb) return null; // No item given.
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var total = 0;
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table.forEach(function(element, index) {
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total += element.weight;
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});
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var avg = total / nb;
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debug('total', total);
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debug('nb', nb);
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debug('avg', avg);
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// Compute amplified urgencies (depending on temperature)
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var ur = {};
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var urgencySum = 0;
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table.forEach(function(element, index) {
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var urgency = element.weight + T * influence * (avg - element.weight);
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if (urgency < 0) urgency = 0;
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urgencySum += urgency;
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ur[element.id] = (ur[element.id] || 0 ) + urgency;
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});
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var cumulatedUrgencies = {};
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var currentUrgency = 0;
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Object.keys(ur).forEach(function(id, index) {
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currentUrgency += ur[id];
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cumulatedUrgencies[id] = currentUrgency;
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});
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if(urgencySum < 1) return null; // No weight given
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// Choose
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var choice = randomFunction() * urgencySum;
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debug('ur', ur);
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debug('cumulatedUrgencies', cumulatedUrgencies);
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debug('urgencySum', urgencySum);
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debug('choice', choice);
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var ids = Object.keys(cumulatedUrgencies);
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for(var i=0; i<ids.length; i++) {
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var id = ids[i];
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var urgency = cumulatedUrgencies[id];
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if(choice <= urgency) {
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debug('return', id);
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return id;
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}
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}
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};
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module.exports = RandomWeightedChoice; |