Initial commit

LICENSE

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+Copyright (c) 2014, The Go-strutils Authors
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+* Redistributions of source code must retain the above copyright notice, this
+  list of conditions and the following disclaimer.
+
+* Redistributions in binary form must reproduce the above copyright notice,
+  this list of conditions and the following disclaimer in the documentation
+  and/or other materials provided with the distribution.
+
+* Neither the name of the {organization} nor the names of its
+  contributors may be used to endorse or promote products derived from
+  this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

README.md

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+# Too
+
+Too is a simple recommendation engine built on top of Redis in Go.
+
+## Installation
+
+Install Too using the go get command:
+
+    $ go get github.com/hjr265/too
+
+The only dependencies are Go distribution and [Redis](http://redis.io).
+
+## Documentation
+
+- [Reference](http://godoc.org/github.com/hjr265/too)
+
+## Contributing
+
+Contributions are welcome.
+
+## License
+
+Too is available under the [BSD (3-Clause) License](http://opensource.org/licenses/BSD-3-Clause).

doc.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+// Package too provides a recommendation engine implementation built on top of Redis
+package too

engine.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+package too
+
+import (
+	"net"
+
+	"github.com/garyburd/redigo/redis"
+)
+
+type Engine struct {
+	c     redis.Conn
+	class string
+
+	Likes    Rater
+	Dislikes Rater
+
+	Similars    Similars
+	Suggestions Suggestions
+}
+
+// New returns a new engine for given class connected to Redis server at addr.
+func New(addr net.Addr, class string) (*Engine, error) {
+	c, err := redis.Dial(addr.Network(), addr.String())
+	if err != nil {
+		return nil, err
+	}
+
+	e := &Engine{
+		c:     c,
+		class: class,
+	}
+	e.Likes = Rater{e, "likes"}
+	e.Dislikes = Rater{e, "dislikes"}
+	e.Similars = Similars{e}
+	e.Suggestions = Suggestions{e}
+	return e, nil
+}

example_test.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+package too_test
+
+import (
+	"fmt"
+	"log"
+	"net"
+
+	"github.com/hjr265/too"
+)
+
+func ExampleEngine() {
+	redisAddr, _ := net.ResolveTCPAddr("tcp", ":6379")
+	te, err := too.New(redisAddr, "movies")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	te.Likes.Add("Sonic", "The Shawshank Redemption")
+	te.Likes.Add("Sonic", "The Godfather")
+	te.Likes.Add("Sonic", "The Dark Knight")
+	te.Likes.Add("Sonic", "Pulp Fiction")
+
+	te.Likes.Add("Mario", "The Godfather")
+	te.Likes.Add("Mario", "The Dark Knight")
+	te.Likes.Add("Mario", "The Shawshank Redemption")
+	te.Likes.Add("Mario", "The Prestige")
+	te.Likes.Add("Mario", "The Matrix")
+
+	te.Likes.Add("Peach", "The Godfather")
+	te.Likes.Add("Peach", "Inception")
+	te.Likes.Add("Peach", "Fight Club")
+	te.Likes.Add("Peach", "WALL·E")
+	te.Likes.Add("Peach", "Princess Mononoke")
+
+	te.Likes.Add("Luigi", "The Prestige")
+	te.Likes.Add("Luigi", "The Dark Knight")
+
+	items, _ := te.Suggestions.For("Luigi", 2)
+	for _, item := range items {
+		fmt.Println(item)
+	}
+
+	// Output:
+	// The Shawshank Redemption
+	// The Matrix
+}

item.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+package too
+
+type Item string

rater.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+package too
+
+import (
+	"fmt"
+
+	"github.com/garyburd/redigo/redis"
+)
+
+type Rater struct {
+	e    *Engine
+	kind string
+}
+
+// Add adds a rating by user for item
+func (r Rater) Add(user User, item Item) error {
+	yes, err := redis.Bool(r.e.c.Do("SISMEMBER", fmt.Sprintf("%s:%s:%s", r.e.class, item, r.kind), user))
+	if err != nil {
+		return err
+	}
+
+	if !yes {
+		_, err = r.e.c.Do("ZINCRBY", fmt.Sprintf("%s:mosts:%s", r.e.class, r.kind), 1, item)
+		if err != nil {
+			return err
+		}
+	}
+
+	_, err = r.e.c.Do("SADD", fmt.Sprintf("%s:%s:%s", r.e.class, user, r.kind), item)
+	if err != nil {
+		return err
+	}
+
+	_, err = r.e.c.Do("SADD", fmt.Sprintf("%s:%s:%s", r.e.class, item, r.kind), user)
+	if err != nil {
+		return err
+	}
+
+	err = r.e.Similars.update(user)
+	if err != nil {
+		return err
+	}
+
+	err = r.e.Suggestions.update(user)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}

similars.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+package too
+
+import (
+	"fmt"
+
+	"github.com/garyburd/redigo/redis"
+)
+
+type Similars struct {
+	e *Engine
+}
+
+// Of returns n users similar to user
+func (s Similars) Of(user User, n int) ([]User, error) {
+	results, err := redis.Strings(s.e.c.Do("ZREVRANGE", fmt.Sprintf("%s:%s:%s", s.e.class, user, "similars"), 0, n-1))
+	if err != nil && err != redis.ErrNil {
+		return nil, err
+	}
+
+	users := []User{}
+	for _, user := range results {
+		users = append(users, User(user))
+	}
+	return users, nil
+}
+
+// Jaccard returns the Jaccard coefficient between user and other
+func (s Similars) Jaccard(user, other User) (float64, error) {
+	likes, err := redis.Strings(s.e.c.Do("SINTER", fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Likes.kind), fmt.Sprintf("%s:%s:%s", s.e.class, other, s.e.Likes.kind)))
+	if err != nil && err != redis.ErrNil {
+		return 0, err
+	}
+
+	dislikes, err := redis.Strings(s.e.c.Do("SINTER", fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Dislikes.kind), fmt.Sprintf("%s:%s:%s", s.e.class, other, s.e.Dislikes.kind)))
+	if err != nil && err != redis.ErrNil {
+		return 0, err
+	}
+
+	antiLikes, err := redis.Strings(s.e.c.Do("SINTER", fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Likes.kind), fmt.Sprintf("%s:%s:%s", s.e.class, other, s.e.Dislikes.kind)))
+	if err != nil && err != redis.ErrNil {
+		return 0, err
+	}
+
+	antiDislikes, err := redis.Strings(s.e.c.Do("SINTER", fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Dislikes.kind), fmt.Sprintf("%s:%s:%s", s.e.class, other, s.e.Likes.kind)))
+	if err != nil && err != redis.ErrNil {
+		return 0, err
+	}
+
+	return float64(len(likes)+len(dislikes)-len(antiLikes)-len(antiDislikes)) / float64(len(likes)+len(dislikes)+len(antiLikes)+len(antiDislikes)), nil
+}
+
+func (s Similars) update(user User) error {
+	items, err := redis.Strings(s.e.c.Do("SUNION", fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Likes.kind), fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Dislikes.kind)))
+	if err != nil && err != redis.ErrNil {
+		return err
+	}
+
+	args := []interface{}{}
+	for _, item := range items {
+		args = append(args, fmt.Sprintf("%s:%s:%s", s.e.class, item, s.e.Likes.kind))
+		args = append(args, fmt.Sprintf("%s:%s:%s", s.e.class, item, s.e.Dislikes.kind))
+	}
+	users, err := redis.Strings(s.e.c.Do("SUNION", args...))
+	if err != nil && err != redis.ErrNil {
+		return err
+	}
+
+	for _, other := range users {
+		if other != string(user) {
+			v, err := s.Jaccard(user, User(other))
+			if err != nil {
+				return err
+			}
+
+			_, err = s.e.c.Do("ZADD", fmt.Sprintf("%s:%s:similars", s.e.class, user), v, other)
+			if err != nil {
+				return err
+			}
+		}
+	}
+	return nil
+}

suggestions.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+package too
+
+import (
+	"fmt"
+
+	"github.com/garyburd/redigo/redis"
+)
+
+type Suggestions struct {
+	e *Engine
+}
+
+// For returns n suggested items for user
+func (s Suggestions) For(user User, n int) ([]Item, error) {
+	results, err := redis.Strings(s.e.c.Do("ZREVRANGE", fmt.Sprintf("%s:%s:%s", s.e.class, user, "suggestions"), 0, n-1))
+	if err != nil && err != redis.ErrNil {
+		return nil, err
+	}
+
+	items := []Item{}
+	for _, item := range results {
+		items = append(items, Item(item))
+	}
+	return items, nil
+}
+
+func (s Suggestions) update(user User) error {
+	similars, err := s.e.Similars.Of(user, 8)
+	if err != nil {
+		return err
+	}
+	if len(similars) == 0 {
+		return nil
+	}
+
+	args := []interface{}{fmt.Sprintf("%s:%s:_tmp", s.e.class, user)}
+	for _, similar := range similars {
+		args = append(args, fmt.Sprintf("%s:%s:%s", s.e.class, similar, s.e.Likes.kind))
+	}
+	_, err = s.e.c.Do("SUNIONSTORE", args...)
+	if err != nil {
+		return err
+	}
+	defer s.e.c.Do("DEL", fmt.Sprintf("%s:%s:_tmp", s.e.class, user))
+
+	items, err := redis.Strings(s.e.c.Do("SDIFF", fmt.Sprintf("%s:%s:_tmp", s.e.class, user), fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Likes.kind), fmt.Sprintf("%s:%s:%s", s.e.class, user, s.e.Dislikes.kind)))
+	if err != nil && err != redis.ErrNil {
+		return err
+	}
+
+	scores := map[string]float64{}
+	for _, item := range items {
+		likers, err := redis.Strings(s.e.c.Do("SMEMBERS", fmt.Sprintf("%s:%s:%s", s.e.class, item, s.e.Likes.kind)))
+		if err != nil && err != redis.ErrNil {
+			return err
+		}
+
+		for _, liker := range likers {
+			score, err := redis.Float64(s.e.c.Do("ZSCORE", fmt.Sprintf("%s:%s:similars", s.e.class, user), liker))
+			if err != nil && err != redis.ErrNil {
+				return err
+			}
+
+			scores[item] += score
+		}
+
+		dislikers, err := redis.Strings(s.e.c.Do("SMEMBERS", fmt.Sprintf("%s:%s:%s", s.e.class, item, s.e.Likes.kind)))
+		if err != nil && err != redis.ErrNil {
+			return err
+		}
+
+		for _, disliker := range dislikers {
+			score, err := redis.Float64(s.e.c.Do("ZSCORE", fmt.Sprintf("%s:%s:similars", s.e.class, user), disliker))
+			if err != nil && err != redis.ErrNil {
+				return err
+			}
+
+			scores[item] -= score
+		}
+
+		total := len(likers) + len(dislikers)
+		if total > 0 {
+			scores[item] /= float64(total)
+		}
+	}
+
+	_, err = s.e.c.Do("DEL", fmt.Sprintf("%s:%s:suggestions", s.e.class, user))
+	if err != nil {
+		return err
+	}
+
+	for _, item := range items {
+		s.e.c.Do("ZADD", fmt.Sprintf("%s:%s:suggestions", s.e.class, user), scores[item], item)
+	}
+	return nil
+}

user.go

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+// Copyright 2014 The Too Authors. All rights reserved.
+
+package too
+
+type User string