1
restaurant-search/util.go

185 lines
5.1 KiB
Go

/*
* Copyright (c) 2015 Alex Yatskov <alex@foosoft.net>
* Author: Alex Yatskov <alex@foosoft.net>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy of
* this software and associated documentation files (the "Software"), to deal in
* the Software without restriction, including without limitation the rights to
* use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
* the Software, and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
* FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
* COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
* IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package main
import (
"github.com/kellydunn/golang-geo"
"log"
"math"
"sort"
)
func innerProduct(features1 Features, features2 Features) float64 {
var result float64
for key, value1 := range features1 {
value2, _ := features2[key]
result += value1 * value2
}
return result
}
func walkMatches(records Records, features Features, minScore float64, callback func(Record, float64)) {
for _, record := range records {
if score := innerProduct(features, record.features); score >= minScore {
callback(record, score)
}
}
}
func statRecords(records Records, features Features, minScore float64) RecordStats {
var stats RecordStats
walkMatches(records, features, minScore, func(record Record, score float64) {
stats.compatibility += record.compatibility
stats.count++
})
return stats
}
func stepRange(rng Range, steps int, callback func(float64)) {
stepSize := (rng.max - rng.min) / float64(steps)
for i := 0; i < steps; i++ {
stepMax := rng.max - stepSize*float64(i)
stepMin := stepMax - stepSize
stepMid := (stepMin + stepMax) / 2
callback(stepMid)
}
}
func findRecords(records Records, features Features, minScore float64) {
var foundRecords Records
walkMatches(records, features, minScore, func(record Record, score float64) {
foundRecords = append(foundRecords, record)
})
sort.Sort(foundRecords)
}
func project(records Records, features Features, featureName string, minScore float64, rng Range, steps int) []Projection {
sampleFeatures := make(Features)
for key, value := range features {
sampleFeatures[key] = value
}
var projection []Projection
stepRange(rng, steps, func(sample float64) {
sampleFeatures[featureName] = sample
stats := statRecords(records, sampleFeatures, minScore)
projection = append(projection, Projection{sample: sample, stats: stats})
})
return projection
}
func computeRecordGeo(records Records, context Context) {
distUserMin := math.MaxFloat64
distUserMax := 0.0
for _, record := range records {
if context.hasPosition {
userPoint := geo.NewPoint(context.latitude, context.longitude)
recordPoint := geo.NewPoint(record.latitude, context.longitude)
record.distanceToUser = userPoint.GreatCircleDistance(recordPoint)
}
if record.distanceToUser < distUserMin {
distUserMin = record.distanceToUser
}
if record.distanceToUser > distUserMax {
distUserMax = record.distanceToUser
}
}
distUserRange := distUserMax - distUserMin
for _, record := range records {
nearby := -((record.distanceToUser-distUserMin)/distUserRange - 0.5) * 2.0
accessible := 1.0 - (record.distanceToStn / context.walkingDist)
if accessible < -1.0 {
accessible = 1.0
} else if accessible > 1.0 {
accessible = 1.0
}
record.features["nearby"] = nearby
record.features["accessible"] = accessible
}
}
func computeRecordPopularity(records Records, context Context) {
for _, record := range records {
historyRows, err := db.Query("SELECT id FROM history WHERE reviewId = (?)", record.id)
if err != nil {
log.Fatal(err)
}
var groupSum float64
var groupCount int
for historyRows.Next() {
var historyId int
if err := historyRows.Scan(&historyId); err != nil {
log.Fatal(err)
}
groupRows, err := db.Query("SELECT categoryId, categoryValue FROM historyGroups WHERE historyId = (?)", historyId)
if err != nil {
log.Fatal(err)
}
recordProfile := make(Features)
for groupRows.Next() {
var categoryId int
var categoryValue float64
if err := groupRows.Scan(&categoryId, &categoryValue); err != nil {
log.Fatal(err)
}
recordProfile[categoryId] = categoryValue
}
if err := groupRows.Err(); err != nil {
log.Fatal(err)
}
groupSum += innerProduct(recordProfile, context.profile)
groupCount++
}
if err := historyRows.Err(); err != nil {
log.Fatal(err)
}
var compatibility float64
if groupCount > 0 {
compatibility = groupSum / float64(groupCount)
}
record.features["compatibility"] = compatibility
}
}