README_GO.rst

Install

To install, you'll need Swig (tested with Swig 4.2.1 on Ubuntu 24.04), and then just:

swig -go -intgosize 64 -cgo -c++ src/annoygomodule.i
mkdir -p $(go env GOPATH)/src/annoy
cp src/annoygomodule_wrap.cxx src/annoy.go src/annoygomodule.h src/annoylib.h src/kissrandom.h test/annoy_test.go $(go env GOPATH)/src/annoy
cd $(go env GOPATH)/src/annoy
go mod init github.com/spotify/annoy
go mod tidy
go test

Background

See the main README.

Go code example

package main

import (
       "fmt"
       "math/rand"

       "github.com/spotify/annoy"
)

func main() {
     f := 40
     t := annoy.NewAnnoyIndexAngular(f)
     for i := 0; i < 1000; i++ {
       item := make([]float32, 0, f)
       for x:= 0; x < f; x++ {
           item = append(item, rand.Float32())
       }
       t.AddItem(i, item)
     }
     t.Build(10)
     t.Save("test.ann")

     annoy.DeleteAnnoyIndexAngular(t)

     t = annoy.NewAnnoyIndexAngular(f)
     t.Load("test.ann")

     result := annoyindex.NewAnnoyVectorInt()
     defer result.Free()
     t.GetNnsByItem(0, 1000, -1, result)
     fmt.Printf("%v\n", result.ToSlice())

}

Right now it only accepts integers as identifiers for items. Note that it will allocate memory for max(id)+1 items because it assumes your items are numbered 0 … n-1. If you need other id's, you will have to keep track of a map yourself.

Full Go API

See annoygomodule.h. Generally the same as Python API except some arguments are not optional. Go binding does not support multithreaded build.

Tests

A simple test is supplied in test/annoy_test.go.

Discuss

Memroy leak in the previous versions has been fixed thanks to swig/swig#2292. (memory leak fix is implemented in https://github.com/Rikanishu/annoy-go)

Go glue written by Taneli Leppä (@rosmo). You can contact me via email (see https://github.com/rosmo).