Native HyperLogLog for node.js

See http://en.wikipedia.org/wiki/HyperLogLog.

Based on https://github.com/avz/hll.

Example

var HLL = require('hll-native').HLL;

var tries = 5;

for(var n = 0; n < tries; n++) {
	var start = Date.now();
	var o = {};

	var obj = new HLL(20);

	for(var i = 0; i < 10000000; i++) {
		obj.add('hello_' + i);
	}

	console.log(
		'[' + (n + 1) + ' / ' + tries + ']',
		'Approximated set size:', obj.count() + '.',
		'Elapsed time:', Date.now() - start, 'ms'
	);
}

[1 / 5] Approximated set size: 10000341. Elapsed time: 2142 ms
[2 / 5] Approximated set size: 10000341. Elapsed time: 2133 ms
[3 / 5] Approximated set size: 10000341. Elapsed time: 2142 ms
[4 / 5] Approximated set size: 10000341. Elapsed time: 2121 ms
[5 / 5] Approximated set size: 10000341. Elapsed time: 2118 ms

Memory usage and error values

|bits|size (bytes) | standard error | |----|---------|--------| | 4 | 16 | 26.00% | | 5 | 32 | 18.38% | | 6 | 64 | 13.00% | | 7 | 128 | 9.19% | | 8 | 256 | 6.50% | | 9 | 512 | 4.60% | | 10 | 1024 | 3.25% | | 11 | 2048 | 2.30% | | 12 | 4096 | 1.62% | | 13 | 8192 | 1.15% | | 14 | 16384 | 0.81% | | 15 | 32768 | 0.57% | | 16 | 65536 | 0.41% | | 17 | 131072 | 0.29% | | 18 | 262144 | 0.20% | | 19 | 524288 | 0.14% | | 20 | 1048576 | 0.10% |

Prototype

/**
 * Create new HyperLogLog storage with specified size and standard error.
 *
 * Memory usage for storage calculated as (1 << bits) bytes.
 * Standard error described in table above
 *
 * @param {number} bits
 */
var HLL = function(bits) {};

/**
 * Add key to storage
 * @param {string} key
 */
HLL.prototype.add = function(key) {};

/**
 * Get approximated set size with selected standard error
 * @returns {number}
 */
HLL.prototype.count = function() {};