Simple Histogram Stats

histogram.js

function Histogram() {
	this.reset();
}

Histogram.prototype.reset = function() {
	this.counts = [];
	this.types = {};
};

Histogram.prototype.add = function(type) {
	if (type in this.types) {
		this.types[type].count++;
	} else {
		var counter = {
		  type: type,
          count: 1
		};

		this.counts.push(counter);
		this.types[type] = counter;
	}
};

Histogram.prototype.count = function() {
	return this.counts.length;
};


Histogram.prototype.array = function() {
	return this.counts;
};

function dsc(a, b) {
  return b.count - a.count;
}


function asc(b, a) {
  return b.count - a.count;
}

Histogram.prototype.sort = function() {
	this.counts.sort(dsc);
};

Histogram.prototype.sum = function() {
  var counts = this.counts;
  var sum = 0, i = 0, il = counts.length;
  for (;i<il;i++) {
    sum += counts[i].count;
  }
  return sum;
};

Histogram.prototype.mean = function() {
  return this.sum() / this.count();
};

Histogram.prototype.medium = function() {
  var mid = this.count() / 2 | 0;
  return this.counts[mid];
};

file_types = new Histogram();
file_types.add('js');
file_types.add('sh');
file_types.add('js');
file_types.add('png');
file_types.add('jpg');
file_types.add('js');
file_types.add('js');
file_types.add('html');
file_types.add('html');

file_types.sort();

console.log('count', file_types.count());
console.log('sum', file_types.sum());
console.log('mean', file_types.mean());
console.log('medium', file_types.medium());


console.log(file_types.array());