bloomfilter - npm Package Compare versions

Comparing version 0.0.12 to 0.0.14

bloomfilter.js

@@ -11,3 +11,4 @@ (function(exports) {
   // each element is a 32-bit integer.  Otherwise, *m* should specify the
-  // number of bits.  *k* specifies the number of hashing functions.
+  // number of bits.  Note that *m* is rounded up to the nearest multiple of
+  // 32.  *k* specifies the number of hashing functions.
   function BloomFilter(m, k) {
@@ -17,6 +18,6 @@ var a;
 
-    this.m = m;
-    this.k = k;
     var n = Math.ceil(m / 32),
         i = -1;
+    this.m = m = n * 32;
+    this.k = k;
 
@@ -77,2 +78,17 @@ if (typedArrays) {
 
+  // Estimated cardinality.
+  BloomFilter.prototype.size = function() {
+    var buckets = this.buckets,
+        bits = 0;
+    for (var i = 0, n = buckets.length; i < n; ++i) bits += popcnt(buckets[i]);
+    return -this.m * Math.log(1 - bits / this.m) / this.k;
+  };
+
+  // http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
+  function popcnt(v) {
+    v -= (v >> 1) & 0x55555555;
+    v = (v & 0x33333333) + ((v >> 2) & 0x33333333);
+    return ((v + (v >> 4) & 0xF0F0F0F) * 0x1010101) >> 24;
+  }
+
   // Fowler/Noll/Vo hashing.
@@ -79,0 +95,0 @@ function fnv_1a(v) {

package.json

 {
   "name": "bloomfilter",
-  "version": "0.0.12",
+  "version": "0.0.14",
   "description": "Fast bloom filter in JavaScript.",
@@ -5,0 +5,0 @@ "keywords": [

README.md

@@ -26,2 +26,12 @@ Bloom Filter
 
+    // Serialisation. Note that bloom.buckets may be a typed array,
+    // so we convert to a normal array first.
+    var array = [].slice.call(bloom.buckets),
+        json = JSON.stringify(array);
+
+    // Deserialisation. Note that the any array-like object is supported, but
+    // this will be used directly, so you may wish to use a typed array for
+    // performance.
+    var bloom = new BloomFilter(array, 3);
+
 Implementation
@@ -28,0 +38,0 @@ --------------

No alert changes

Improved metrics

Total package byte prevSize

7482

increased by15.55%

Lines of code

123

increased by12.84%

Number of lines in readme file

49

increased by25.64%

No dependency changes