Now with cardinality functions

bitset.go

@@ -371,6 +371,25 @@ func (b *BitSet) Difference(compare *BitSet) (result *BitSet) {
 	return
 }
 
+// computes the cardinality of the differnce
+func (b *BitSet) DifferenceCardinality(compare *BitSet) (uint) {	
+	panicIfNull(b)
+	panicIfNull(compare)
+	l := int(compare.wordCount()) 
+	if l > int(b.wordCount()) {
+		 l = int(b.wordCount())  
+	}
+	cnt := uint64(0)
+	for i := 0; i < l ; i++ {
+	    cnt += popcount_2(b.set[i] &^ compare.set[i])
+	}
+	for i := l; i < len(b.set) ; i++ {
+		cnt += popcount_2(b.set[i])
+	}
+	return uint(cnt)
+}
+
+
 // Difference of base set and other set
 // This is the BitSet equivalent of &^ (and not)
 func (b *BitSet) InPlaceDifference(compare *BitSet)  {
@@ -411,6 +430,20 @@ func (b *BitSet) Intersection(compare *BitSet) (result *BitSet) {
 	return
 }
 
+
+// Computes the cardinality of the union
+func (b *BitSet) IntersectionCardinality(compare *BitSet) (uint) {
+	panicIfNull(b)
+	panicIfNull(compare)
+	b, compare = sortByLength(b, compare)
+	cnt := uint64(0)
+	for i, word := range b.set {
+		cnt += popcount_2(word & compare.set[i]) 
+	}
+	return uint(cnt)
+}
+
+
 // Intersection of base set and other set
 // This is the BitSet equivalent of & (and)
 func (b *BitSet) InPlaceIntersection(compare *BitSet)  {
@@ -447,6 +480,21 @@ func (b *BitSet) Union(compare *BitSet) (result *BitSet) {
 	return
 }
 
+func (b *BitSet) UnionCardinality(compare *BitSet) (uint) {
+	panicIfNull(b)
+	panicIfNull(compare)
+	b, compare = sortByLength(b, compare)
+	cnt := uint64(0)
+	for i, word := range b.set {
+		cnt += popcount_2(word | compare.set[i])
+	}
+	for i := len(b.set); i < len(compare.set) ; i++ {
+		cnt += popcount_2(compare.set[i])
+	}
+
+	return uint(cnt)
+}
+
 
 // Union of base set and other set
 // This is the BitSet equivalent of | (or)
@@ -484,6 +532,23 @@ func (b *BitSet) SymmetricDifference(compare *BitSet) (result *BitSet) {
 	return
 }
 
+// computes the cardinality of the symmetric difference
+func (b *BitSet) SymmetricDifferenceCardinality(compare *BitSet) (uint) {
+	panicIfNull(b)
+	panicIfNull(compare)
+	b, compare = sortByLength(b, compare)
+	cnt := uint64(0)
+	for i, word := range b.set {
+		cnt += popcount_2(word ^ compare.set[i])
+	}
+	for i := len(b.set); i < len(compare.set) ; i++ {
+		cnt += popcount_2(compare.set[i])
+	}
+
+	return uint(cnt)
+}
+
+
 // SymmetricDifference of base set and other set
 // This is the BitSet equivalent of ^ (xor)
 func (b *BitSet) InPlaceSymmetricDifference(compare *BitSet)  {

bitset_test.go

@@ -188,7 +188,7 @@ func TestCount(t *testing.T) {
 	v := New(tot)
 	checkLast := true
 	for i := uint(0); i < tot; i++ {
-		sz := v.Count()
+		sz := uint(v.Count())
 		if sz != i {
 			t.Errorf("Count reported as %d, but it should be %d", sz, i)
 			checkLast = false
@@ -197,7 +197,7 @@ func TestCount(t *testing.T) {
 		v.Set(i)
 	}
 	if checkLast {
-		sz := v.Count()
+		sz := uint(v.Count())
 		if sz != tot {
 			t.Errorf("After all bits set, size reported as %d, but it should be %d", sz, tot)
 		}
@@ -209,7 +209,7 @@ func TestCount2(t *testing.T) {
 	tot := uint(64*4 + 11) // just some multi unit64 number
 	v := New(tot)
 	for i := uint(0); i < tot; i += 3 {
-		sz := v.Count()
+		sz := uint(v.Count())
 		if sz != i/3 {
 			t.Errorf("Count reported as %d, but it should be %d", sz, i)
 			break
@@ -422,6 +422,13 @@ func TestUnion(t *testing.T) {
 	for i := uint(100); i < 200; i++ {
 		b.Set(i)
 	}
+	if a.UnionCardinality(b) != 200 {
+		t.Errorf("Union should have 200 bits set, but had %d", a.UnionCardinality(b))
+	}
+	if a.UnionCardinality(b) != b.UnionCardinality(a) {
+		t.Errorf("Union should be symmetric")
+	}
+
 	c := a.Union(b)
 	d := b.Union(a)
 	if c.Count() != 200 {
@@ -468,6 +475,12 @@ func TestIntersection(t *testing.T) {
 	for i := uint(100); i < 200; i++ {
 		b.Set(i)
 	}
+	if a.IntersectionCardinality(b) != 50 {
+		t.Errorf("Intersection should have 50 bits set, but had %d", a.IntersectionCardinality(b))
+	}
+	if a.IntersectionCardinality(b) != b.IntersectionCardinality(a) {
+		t.Errorf("Intersection should be symmetric")
+	}
 	c := a.Intersection(b)
 	d := b.Intersection(a)
 	if c.Count() != 50 {
@@ -515,6 +528,13 @@ func TestDifference(t *testing.T) {
 	for i := uint(100); i < 200; i++ {
 		b.Set(i)
 	}
+	if a.DifferenceCardinality(b) != 50 {
+		t.Errorf("a-b Difference should have 50 bits set, but had %d", a.DifferenceCardinality(b))
+	}
+	if b.DifferenceCardinality(a) != 150 {
+		t.Errorf("b-a Difference should have 150 bits set, but had %d", b.DifferenceCardinality(a))
+	}
+
 	c := a.Difference(b)
 	d := b.Difference(a)
 	if c.Count() != 50 {
@@ -564,6 +584,13 @@ func TestSymmetricDifference(t *testing.T) {
 	for i := uint(100); i < 200; i++ {
 		b.Set(i)
 	}
+	if a.SymmetricDifferenceCardinality(b) != 150 {
+		t.Errorf("a^b Difference should have 150 bits set, but had %d", a.SymmetricDifferenceCardinality(b))
+	}
+	if b.SymmetricDifferenceCardinality(a) != 150 {
+		t.Errorf("b^a Difference should have 150 bits set, but had %d", b.SymmetricDifferenceCardinality(a))
+	}
+
 	c := a.SymmetricDifference(b)
 	d := b.SymmetricDifference(a)
 	if c.Count() != 150 {