RoaringBitmap

This is a go port of the Roaring bitmap data structure. The original java version can be found at https://github.com/lemire/RoaringBitmap and the supporting paper is

Samy Chambi, Daniel Lemire, Owen Kaser, Robert Godin, Better bitmap performance with Roaring bitmaps, Software: Practice and Experience (to appear) http://arxiv.org/abs/1402.6407

The Java and Go version are meant to be binary compatible: you can save bitmaps from a Java program and load them back in Go, and vice versa.

This code is licensed under Apache License, Version 2.0 (ASL2.0).

Contributors: Todd Gruben (@tgruben), Daniel Lemire (@lemire), Elliot Murphy (@statik), Bob Potter (@bpot)

Dependencies

• go get github.com/smartystreets/goconvey/convey
• go get github.com/willf/bitset

Naturally, you also need to grab the roaring code itself:

• go get github.com/tgruben/roaring

Example

Here is a simplified but complete example:

package main

import (
    "fmt"
    "github.com/tgruben/roaring"
    "bytes"
)


func main() {
    // example inspired by https://github.com/fzandona/goroar
    fmt.Println("==roaring==")
    rb1 := roaring.BitmapOf(1, 2, 3, 4, 5, 100, 1000)
    fmt.Println(rb1.String())

    rb2 := roaring.BitmapOf(3, 4, 1000)
    fmt.Println(rb2.String())

    rb3 := roaring.NewRoaringBitmap()
    fmt.Println(rb3.String())

    fmt.Println("Cardinality: ", rb1.GetCardinality())

    fmt.Println("Contains 3? ", rb1.Contains(3))

    rb1.And(rb2)

    rb3.Add(1)
    rb3.Add(5)

    rb3.Or(rb1)

    // prints 1, 3, 4, 5, 1000
    i := rb3.Iterator()
    for i.HasNext() {
        fmt.Println(i.Next())
    }
    fmt.Println()

    // next we include an example of serialization
    buf := new(bytes.Buffer)
    rb1.WriteTo(buf) // we omit error handling
    newrb:= roaring.NewRoaringBitmap()
    newrb.ReadFrom(buf)
    if rb1.Equals(newrb) {
    	fmt.Println("I wrote the content to a byte stream and read it back.")
    }
}

If you wish to use serialization and handle errors, you might want to consider the following sample of code:

	rb := BitmapOf(1, 2, 3, 4, 5, 100, 1000)
	buf := new(bytes.Buffer)
	size,err:=rb.WriteTo(buf)
	if err != nil {
		t.Errorf("Failed writing")
	}
	newrb:= NewRoaringBitmap()
	size,err=newrb.ReadFrom(buf)
	if err != nil {
		t.Errorf("Failed reading")
	}
	if ! rb.Equals(newrb) {
		t.Errorf("Cannot retrieve serialized version")
	}

Documentation

Current documentation is available at http://godoc.org/github.com/tgruben/roaring

Benchmark

Type

     go test -bench Benchmark -run -

Alternative

For an alternative implementation in Go, see https://github.com/fzandona/goroar The two versions were written independently.