groupstage module vs fifa2014

gs-vs-fifa2014.js

var seeds = [
  // top 8 seeds
  'BRZ', // brazil
  'SPA', // spain
  'GER', // germany
  'ARG', // argentina
  'COL', // columbia
  'BEL', // belgium
  'URU', // uruguay
  'SWI', // switzerland
  // bottom seeds
  'NED', // netherlands
  'ITA', // italy
  'ENG', // england
  'CHI', // chile
  'USA', // united states
  'POR', // portugal
  'GRE', // greece
  'BIH', // bosnia and herzegovina
  'CIV', // ivory coast 
  'CRO', // croatia 
  'RUS', // russia
  'FRA', // france
  'ECU', // ecuador 
  'GHA', // ghana 
  'MEX', // mexico
  'CRC', // costa rica
  'ALG', // algeria 
  'NGA', // nigeria 
  'HON', // honduras
  'JPN', // japan 
  'IRN', // iran
  'KOR', // south korea 
  'AUS', // australia 
  'CMR'  // cameroon
];

var assert = require('assert');
assert(seeds.length === 8*4, 'have not missed out any teams');

// expected sum of seeds is sum of integers up to seeds.length divided by num groups
var seedSum = (seeds.length*(seeds.length+1)/2) / 8;


console.log('fifa groups 2014:');
var fifaGroups = [
  ['BRZ', 'MEX', 'CMR', 'CRO'],
  ['NED', 'CHI', 'AUS', 'SPA'],
  ['COL', 'CIV', 'JPN', 'GRE'],
  ['CRC', 'ITA', 'ENG', 'URU'],
  ['FRA', 'SWI', 'ECU', 'HON'],
  ['ARG', 'IRN', 'NGA', 'BIH'],
  ['GER', 'POR', 'GHA', 'USA'],
  ['BEL', 'ALG', 'RUS', 'KOR']
];

var calculateSum = function (group) {
  return group.reduce(function (sum, code) {
    var idx = seeds.indexOf(code);
    assert(idx >= 0, 'index exists for ' + code);
    return sum + (idx + 1);
  }, 0);
};
var masterSum = 0;
fifaGroups.forEach(function (group, i) {
  var sum = calculateSum(group);
  console.log('  Group', (i + 1) + ':', group.join(', '), '( seed sum is ' + sum + ' )');
  masterSum += sum;
});
assert(masterSum === seedSum*8, 'we did math correctly');

// so sort by strength:
console.log('Toughest groups:')
fifaGroups.sort(function (g1, g2) {
  return calculateSum(g1) - calculateSum(g2);
}).slice(0, 3).forEach(function (group, i) {
  var sum = calculateSum(group);
  console.log('  #' + (i+1) + ':',  group.join(', '), '(' + sum + ')');
});




console.log('\nactually fair groups:');
var GS = require('./');
var gs = new GS(8*4, { groupSize: 4 });

[1,2,3,4,5,6,7,8].forEach(function (g) {
  var sum = 0;
  var ps = [];
  gs.players({ s: g }).forEach(function (p) {
    ps.push(seeds[p-1]);
    sum += p;
  });
  console.log('  Group', g + ':', ps.join(', '), '( seed sum is ' + sum + ' )');
});

How bad could it have been? Looking at the draw procedures, it is possible to get the following combination of groups:

var toughestPossible = ['BRZ', 'NED', 'USA', 'ITA']; // seed sum 33
var weakestPossible = ['SWI', 'CMR', 'AUS', 'NGA']; // seed sum 97
// 6 other groups

The toughest one relies on Italy being picked as the extraneous european team and it being matched up with Brazil as the pot X winner. Entirely possible, but obviously much worse.