var elements = {"Hydrogen":{"weight":389,"value":400},"Helium":{"weight":309,"value":380},"Lithium":{"weight":339,"value":424},"Beryllium":{"weight":405,"value":387},"Boron":{"weight":12,"value":174},"Carbon":{"weight":298,"value":483},"Nitrogen":{"weight":409,"value":303},"Oxygen":{"weight":432,"value":497},"Fluorine":{"weight":414,"value":306},"Neon":{"weight":149,"value":127},"Sodium":{"weight":247,"value":341},"Magnesium":{"weight":327,"value":98},"Aluminium":{"weight":195,"value":343},"Silicon":{"weight":356,"value":122},"Phosphorus":{"weight":49,"value":157},"Sulfur":{"weight":151,"value":438},"Chlorine":{"weight":56,"value":460},"Argon":{"weight":317,"value":395},"Potassium":{"weight":383,"value":221},"Calcium":{"weight":281,"value":395},"Scandium":{"weight":394,"value":79},"Titanium":{"weight":377,"value":303},"Vanadium":{"weight":381,"value":308},"Chromium":{"weight":299,"value":295},"Manganese":{"weight":114,"value":447},"Iron":{"weight":422,"value":360},"Cobalt":{"weight":288,"value":249},"Nickel":{"weight":458,"value":482},"Copper":{"weight":91,"value":314},"Zinc":{"weight":104,"value":140},"Gallium":{"weight":470,"value":254},"Germanium":{"weight":77,"value":25},"Arsenic":{"weight":213,"value":393},"Selenium":{"weight":419,"value":96},"Bromine":{"weight":114,"value":199},"Krypton":{"weight":490,"value":8},"Rubidium":{"weight":278,"value":367},"Strontium":{"weight":310,"value":159},"Yttrium":{"weight":175,"value":109},"Zirconium":{"weight":453,"value":288},"Niobium":{"weight":56,"value":375},"Molybdenum":{"weight":147,"value":343},"Technetium":{"weight":123,"value":105},"Ruthenium":{"weight":325,"value":214},"Rhodium":{"weight":418,"value":428},"Palladium":{"weight":353,"value":387},"Silver":{"weight":182,"value":429},"Cadmium":{"weight":411,"value":394},"Indium":{"weight":322,"value":329},"Tin":{"weight":490,"value":436},"Antimony":{"weight":28,"value":479},"Tellurium":{"weight":443,"value":305},"Iodine":{"weight":345,"value":253},"Xenon":{"weight":463,"value":19},"Caesium":{"weight":361,"value":416},"Barium":{"weight":307,"value":417},"Lanthanum":{"weight":291,"value":453},"Cerium":{"weight":259,"value":414},"Praseodymium":{"weight":58,"value":83},"Neodymium":{"weight":127,"value":475},"Promethium":{"weight":11,"value":480},"Samarium":{"weight":361,"value":192},"Europium":{"weight":409,"value":271},"Gadolinium":{"weight":86,"value":231},"Terbium":{"weight":100,"value":75},"Dysprosium":{"weight":166,"value":128},"Holmium":{"weight":54,"value":109},"Erbium":{"weight":432,"value":399},"Thulium":{"weight":361,"value":395},"Ytterbium":{"weight":417,"value":222},"Lutetium":{"weight":311,"value":224},"Hafnium":{"weight":138,"value":101},"Tantalum":{"weight":177,"value":397},"Tungsten":{"weight":14,"value":234},"Rhenium":{"weight":480,"value":141},"Osmium":{"weight":208,"value":490},"Iridium":{"weight":121,"value":68},"Platinum":{"weight":182,"value":29},"Gold":{"weight":339,"value":267},"Mercury":{"weight":259,"value":438},"Thallium":{"weight":342,"value":425},"Lead":{"weight":65,"value":395},"Bismuth":{"weight":33,"value":497},"Polonium":{"weight":293,"value":394},"Astatine":{"weight":392,"value":210},"Radon":{"weight":116,"value":203},"Francium":{"weight":433,"value":253},"Radium":{"weight":303,"value":109},"Actinium":{"weight":149,"value":317},"Thorium":{"weight":342,"value":129},"Protactinium":{"weight":457,"value":50},"Uranium":{"weight":118,"value":77},"Neptunium":{"weight":117,"value":300},"Plutonium":{"weight":106,"value":455},"Americium":{"weight":66,"value":365},"Curium":{"weight":393,"value":407},"Berkelium":{"weight":289,"value":458},"Californium":{"weight":302,"value":322},"Einsteinium":{"weight":455,"value":94},"Fermium":{"weight":216,"value":347},"Mendelevium":{"weight":304,"value":331},"Nobelium":{"weight":49,"value":236},"Lawrencium":{"weight":84,"value":351},"Rutherfordium":{"weight":345,"value":233},"Dubnium":{"weight":168,"value":187},"Seaborgium":{"weight":361,"value":125},"Bohrium":{"weight":236,"value":479},"Hassium":{"weight":201,"value":353},"Meitnerium":{"weight":278,"value":307},"Darmstadtium":{"weight":308,"value":344},"Roentgenium":{"weight":171,"value":201},"Copernicium":{"weight":251,"value":460},"Ununtrium":{"weight":158,"value":52},"Ununquadium":{"weight":282,"value":113},"Ununpentium":{"weight":145,"value":497},"Ununhexium":{"weight":459,"value":449},"Ununseptium":{"weight":327,"value":7},"Ununoctium":{"weight":184,"value":411}};
function length(obj) {
var length = 0;
for (var i in obj)
length++;
return length;
}
function clone(obj) {
obj = JSON.parse(JSON.stringify(obj));
return obj;
}
function pickRandomProperty(obj) {
var result;
var count = 0;
for (var prop in obj)
if (Math.random() < 1 / ++count)
result = prop;
return result;
}
var Chromosome = function(members) {
this.members = members;
for (var element in this.members)
{
if (typeof this.members[element]['active'] == 'undefined')
{
this.members[element]['active'] = Math.round( Math.random() );
}
}
this.mutate();
this.calcScore();
};
Chromosome.prototype.mutate = function() {
if (Math.random() > this.mutationRate)
return false;
var element = pickRandomProperty(this.members);
this.members[element]['active'] = Number(! this.members[element]['active']);
};
Chromosome.prototype.calcScore = function() {
if (this.score)
return this.score;
this.value = 0;
this.weight = 0;
this.score = 0;
for (var element in this.members)
{
if (this.members[element]['active'])
{
this.value += this.members[element]['value'];
this.weight += this.members[element]['weight'];
}
}
this.score = this.value;
if (this.weight > this.maxWeight)
{
this.score -= (this.weight - this.maxWeight) * 50;
}
return this.score;
};
Chromosome.prototype.mateWith = function(other) {
var child1 = {};
var child2 = {};
var pivot = Math.round( Math.random() * (length(this.members) - 1) );
var i = 0;
for (var element in elements)
{
if (i < pivot)
{
child1[element] = clone(this.members[element]);
child2[element] = clone(other.members[element]);
}
else
{
child2[element] = clone(this.members[element]);
child1[element] = clone(other.members[element]);
}
i++;
}
child1 = new Chromosome(child1);
child2 = new Chromosome(child2);
return [child1, child2];
};
Chromosome.prototype.weight = 0;
Chromosome.prototype.value = 0;
Chromosome.prototype.members = [];
Chromosome.prototype.maxWeight = 1000;
Chromosome.prototype.mutationRate = 0.7;
Chromosome.prototype.score = 0;
var Population = function(elements, size)
{
if ( ! size )
size = 20;
this.elements = elements;
this.size = size;
this.fill();
};
Population.prototype.fill = function() {
while (this.chromosomes.length < this.size)
{
if (this.chromosomes.length < this.size / 3)
{
this.chromosomes.push( new Chromosome( clone(this.elements) ) );
}
else
{
this.mate();
}
}
};
Population.prototype.sort = function() {
this.chromosomes.sort(function(a, b) { return b.calcScore() - a.calcScore(); });
};
Population.prototype.kill = function() {
var target = Math.floor( this.elitism * this.chromosomes.length );
while (this.chromosomes.length > target)
{
this.chromosomes.pop();
}
};
Population.prototype.mate = function() {
var key1 = pickRandomProperty(this.chromosomes);
var key2 = key1;
while (key2 == key1)
{
key2 = pickRandomProperty(this.chromosomes);
}
var children = this.chromosomes[key1].mateWith(this.chromosomes[key2]);
this.chromosomes = this.chromosomes.concat(children);
};
Population.prototype.generation = function(log) {
this.sort();
this.kill();
this.mate();
this.fill();
this.sort();
};
Population.prototype.display = function(i, noImprovement) {
document.getElementById('gen_no').innerHTML = i;
document.getElementById('weight').innerHTML = this.chromosomes[0].weight;
document.getElementById('value').innerHTML = this.chromosomes[0].score;
document.getElementById('nochange').innerHTML = noImprovement;
};
Population.prototype.run = function(threshold, noImprovement, lastScore, i) {
if ( ! threshold )
threshold = 1000;
if ( ! noImprovement )
noImprovement = 0;
if ( ! lastScore )
lastScore = false;
if ( ! i )
i = 0;
if (noImprovement < threshold)
{
lastScore = this.chromosomes[0].calcScore();
this.generation();
if (lastScore >= this.chromosomes[0].calcScore())
{
noImprovement++;
}
else
{
noImprovement = 0;
}
i++;
if (i % 10 == 0)
this.display(i, noImprovement);
var scope = this;
setTimeout(function() { scope.run(threshold, noImprovement, lastScore, i) }, 1);
return false;
}
this.display(i, noImprovement);
};
Population.prototype.elitism = 0.2;
Population.prototype.chromosomes = [];
Population.prototype.size = 100;
Population.prototype.elements = false;
var p;
p = new Population(clone(elements));
document.getElementById('runbutton').onclick = function() {
p.run(document.getElementById('runfor').value);
};
<table>
<tr>
<td><strong>Generation</strong></td>
<td id="gen_no"></td>
<tr>
<td><strong>Best Value</strong></td>
<td id="value"></td>
<tr>
<td><strong>Weight</strong></td>
<td id="weight"></td>
<tr>
<td><strong>No change in</strong></td>
<td id="nochange"></td>
</table>
<div>
<input type="range" min=1 max=1000 value=100 id="runfor" onchange="document.getElementById('runforspan').innerHTML=this.value;">
<br>
<button id="runbutton">Run for <span id='runforspan'>100</span>-generation threshold</button>
</div>
body {
font-family:Helvetica, Arial, sans-serif;
font-size:14px;
}
table, div, input {
width: 200px;
margin:10px auto;
}