idf/lib/vocab.js

Function that takes a Term-Document map; computes IDFs.

/*DOCSTRING: HELPER FUNCTION to Compute the unique vocabulary set of a corpus.*/
module.exports = (function()
{
  Set.prototype.__arrUnion = function(arr)
  {
    arr.forEach(this.add, this); //'this' refers to the Set that called the method here.
  }

  return function(matr) // For a given 2D array, returns the set union of its elements.
         {
          var unionOfVector = new Set();
          matr.forEach(unionOfVector.__arrUnion, unionOfVector); //union in-place
          return unionOfVector;
         };

})();