/
richard.go
190 lines (142 loc) · 3.04 KB
/
richard.go
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package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"math"
"os"
)
type InnerStruct map[string]float64
type OuterStruct map[string]InnerStruct
type MetricFunc func(p1, p2 InnerStruct) float64
type Richard struct {
data OuterStruct
}
func (r *Richard) CommonKeys(v1, v2 InnerStruct) InnerStruct {
common := make(InnerStruct)
for key, _ := range v1 {
if v2[key] != 0 {
common[key] = 1
}
}
return common
}
func (r *Richard) SimDistance(v1, v2 InnerStruct) float64 {
common := r.CommonKeys(v1, v2)
n := float64(len(common))
if n == 0 {
return 0.0
}
var sum_of_squares float64
for key, _ := range common {
sum_of_squares += math.Pow(v1[key]-v2[key], 2)
}
return 1 / (1 + sum_of_squares)
}
func (r *Richard) SimPearson(v1, v2 InnerStruct) float64 {
common := r.CommonKeys(v1, v2)
n := float64(len(common))
if n == 0 {
return 0
}
var sum1, sum2, sumsq1, sumsq2, sump float64
for key, _ := range common {
sum1 += v1[key]
sumsq1 += math.Pow(v1[key], 2)
sum2 += v2[key]
sumsq2 += math.Pow(v2[key], 2)
sump += v1[key] * v2[key]
}
num := sump - ((sum1 * sum2) / n)
den := math.Sqrt((sumsq1 - (math.Pow(sum1, 2))/n) * (sumsq2 - (math.Pow(sum2, 2))/n))
if den == 0 {
return 0
}
return num / den
}
func (r *Richard) Recommend(thekey string, metric MetricFunc) InnerStruct {
total := make(InnerStruct)
totalSim := make(InnerStruct)
ranking := make(InnerStruct)
k1 := r.data[thekey]
for p2, k2 := range r.data {
if thekey != p2 {
common := r.CommonKeys(k1, k2)
sim := metric(k1, k2)
if sim < 0 {
continue
}
for key, value := range k2 {
if common[key] > 0 {
continue
}
total[key] += value * sim
totalSim[key] += sim
}
}
}
for key, _ := range total {
ranking[key] = total[key] / totalSim[key]
}
return ranking
}
func (r *Richard) Transform() OuterStruct {
result := make(OuterStruct)
for name, ratings := range r.data {
for item, rating := range ratings {
if result[item] == nil {
result[item] = make(InnerStruct)
}
result[item][name] = rating
}
}
return result
}
func (r *Richard) Top(thekey string, n int, metric MetricFunc) []float64 {
if n == 0 {
n = 5
}
scores := make([]float64, 0)
for key, values := range r.data {
if key == thekey {
continue
}
scores = append(scores, metric(r.data[thekey], values))
}
if n > len(r.data) {
n = len(r.data)
}
return scores
}
func (r *Richard) ImportJSON(filename string) {
input, err := ioutil.ReadFile(filename)
if err != nil {
fmt.Println("[ERROR]", "[ReadFile]", err)
os.Exit(1)
}
err = json.Unmarshal(input, &r.data)
if err != nil {
fmt.Println("[ERROR]", "[Unmarshal]", err)
os.Exit(1)
}
}
func (r *Richard) Sim(n int) {
if n == 0 {
n = 5
}
for key, _ := range r.data {
fmt.Print(key)
fmt.Println(r.Top(key, 5, r.SimPearson))
}
}
func main() {
var r Richard
r.ImportJSON(os.Args[1])
r.data = r.Transform()
for p1, _ := range r.data {
fmt.Println(p1)
fmt.Println(r.Recommend(p1, r.SimDistance))
fmt.Println(r.Recommend(p1, r.SimPearson))
}
r.Sim(5)
}