Uniformly sampling random subsets in webppl

random-subsets.js

// uses lodash, not underscore

var sampleSubset = function(xs) {
  var n = xs.length;

  var toBinary = function(dec){
    // convert decimal to binary
    var _s = (dec >>> 0).toString(2);
    // do left padding
    var k = _s.length;
    var s = k < n ? ( _.repeat('0', n - k) + _s ) : _s;

    var intArray = map(function(x) { return !!(x == '1') }, s);

    return intArray;
  }

  var template = toBinary(randomInteger(Math.pow(2, n)), n);
  var zipped = _.zip(xs, template)
  return _.map(filter(function(pair) { return pair[1] }, zipped), '0')
}