simple ordering implementation for foursquare hackathon dish ranking app - messy messy messy!

gistfile1.js

var B = {};
var REC = { "_id" : "HZXXY3", "venues" : { "A" : [ "B" ], "B" : [ "C" ], "C" : [ ] } };
var RECS = [rec];
TESTJSON = [{ "_id" : "HZXXY3", "venues" : { "A" : [ "B" ], "B" : [ "C" ], "C" : [ ] } }, { "_id" : "HZXXY4", "venues" : { "A" : [ "B" ], "B" : [ "C" ], "C" : [ ] } }, { "_id" : "HZXXY5", "venues" : { "A" : [ "B", "C"], "B" : [ "A", "C" ], "C" : ["A"] } }];

function increment_venue_ballot(v, k, ballot) {
  if (typeof(ballot[v]) == "undefined") {
    ballot[v] = {"for": 0, "against": 0}; // initialize ballot with 0s
  }
  ++ballot[v][k]; // increment for or against, depending on value of k
  return ballot;
}

// increment_venue_ballot("a","for", {}) 
// { a: { for: 1, against: 0 } }

function parse_venue(rec, ballot) {
  for (var winner in rec.venues) {
      // increment for vote for winner
      if (rec.venues[winner].length > 0) {
        ballot = increment_venue_ballot(winner, "for", ballot);
      }
      // increment against votes for losers
      for (var loser_idx in rec.venues[winner]) {
           var loser = rec.venues[winner][loser_idx];
        ballot = increment_venue_ballot(loser, "against", ballot);
      }
  }
  return ballot;
}

function parse_records(recs) {
  var ballot = {};
  for (var i in recs) { // parse all records
    ballot = parse_venue(recs[i], ballot);
  }
  return ballot;
}

// parse_records(RECS)
// { A: { for: 1, against: 0 }, B: { for: 1, against: 1 }, C: { for: 0, against: 1 } }

function get_margin(votes) {
  return votes["for"] - votes["against"]; // calculate vote margin
}

// get_margin({"for":1, "against":2})
// => -1

function get_venue_tallies(ballot) {
  var tally = [];
  
  for (var venue in ballot) {
      var against = ballot[venue].against; // votes against
      var votes = ballot[venue]; // votes
      var margin = get_margin(votes); // vote margin
    // store stats in dictionary
    tally.push({"venue":venue,
                "margin":margin,
                "against":against});
  }
  return tally;
}

/*
get_venue_tallies(parse_records(RECS))

[ { venue: 'A', margin: 1, against: 0 },
  { venue: 'B', margin: 0, against: 1 },
  { venue: 'C', margin: -1, against: 1 } ]
*/


function mysortfunction(a, b) {
  // sorting on two fields!
  var margin1 = a.margin;
  var margin2 = b.margin;

  var against1 = a.against;
  var against2 = b.against;

  if (margin1 != margin2) {
    if (margin1 < margin2) return -1;
    if (margin1 > margin2) return 1;
    return 0;
  }
  if (against1 < against2) return 1;
  if (against1 > against2) return -1;
  return 0;
}

function rank_venues(tallies) {
  // sort venues by votes, descending in awesomeness
  return tallies.sort(mysortfunction).reverse();
}

function main (){
  var records = TESTJSON;
  var ballot = parse_records(records);
  tallies = get_venue_tallies(ballot);
  ranks = rank_venues(tallies);

  return ranks;
}


/*
main()
[ { venue: 'A', margin: 1, against: 2 },
  { venue: 'B', margin: 0, against: 3 },
  { venue: 'C', margin: -3, against: 4 } ]
*/