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index.go
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index.go
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// Copyright 2022 gorse Project Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package search
import (
"fmt"
"github.com/chewxy/math32"
"github.com/zhenghaoz/gorse/base/floats"
"github.com/zhenghaoz/gorse/base/log"
"go.uber.org/zap"
"modernc.org/sortutil"
"reflect"
"sort"
)
type Vector interface {
Distance(vector Vector) float32
Terms() []string
IsHidden() bool
Centroid(vectors []Vector, indices []int32) CentroidVector
}
type DenseVector struct {
data []float32
terms []string
isHidden bool
}
func NewDenseVector(data []float32, terms []string, isHidden bool) *DenseVector {
return &DenseVector{
data: data,
terms: terms,
isHidden: isHidden,
}
}
func (v *DenseVector) Distance(vector Vector) float32 {
feedbackVector, isFeedback := vector.(*DenseVector)
if !isFeedback {
log.Logger().Fatal("vector type mismatch",
zap.String("expect", reflect.TypeOf(v).String()),
zap.String("actual", reflect.TypeOf(vector).String()))
}
return -floats.Dot(v.data, feedbackVector.data)
}
func (v *DenseVector) Terms() []string {
return v.terms
}
func (v *DenseVector) IsHidden() bool {
return v.isHidden
}
func (v *DenseVector) Centroid(_ []Vector, _ []int32) CentroidVector {
panic("not implemented")
}
type DictionaryVector struct {
isHidden bool
terms []string
indices []int32
values []float32
norm float32
}
func NewDictionaryVector(indices []int32, values []float32, terms []string, isHidden bool) *DictionaryVector {
sort.Sort(sortutil.Int32Slice(indices))
var norm float32
for _, i := range indices {
norm += values[i]
}
norm = math32.Sqrt(norm)
return &DictionaryVector{
isHidden: isHidden,
terms: terms,
indices: indices,
values: values,
norm: norm,
}
}
func (v *DictionaryVector) Dot(vector *DictionaryVector) (float32, float32) {
i, j, sum, common := 0, 0, float32(0), float32(0)
for i < len(v.indices) && j < len(vector.indices) {
if v.indices[i] == vector.indices[j] {
sum += v.values[v.indices[i]]
common++
i++
j++
} else if v.indices[i] < vector.indices[j] {
i++
} else if v.indices[i] > vector.indices[j] {
j++
}
}
return sum, common
}
const similarityShrink = 100
func (v *DictionaryVector) Distance(vector Vector) float32 {
var score float32
if dictVec, isDictVec := vector.(*DictionaryVector); !isDictVec {
panic(fmt.Sprintf("unexpected vector type: %v", reflect.TypeOf(vector)))
} else {
dot, common := v.Dot(dictVec)
if dot > 0 {
score = -dot / v.norm / dictVec.norm * common / (common + similarityShrink)
}
}
return score
}
func (v *DictionaryVector) Terms() []string {
return v.terms
}
func (v *DictionaryVector) IsHidden() bool {
return v.isHidden
}
type CentroidVector interface {
Distance(vector Vector) float32
}
type DictionaryCentroidVector struct {
data map[int32]float32
norm float32
}
func (v DictionaryVector) Centroid(vectors []Vector, indices []int32) CentroidVector {
data := make(map[int32]float32)
for _, i := range indices {
vector, isDictVector := vectors[i].(*DictionaryVector)
if !isDictVector {
panic(fmt.Sprintf("unexpected vector type: %v", reflect.TypeOf(vector)))
}
for _, i := range vector.indices {
data[i] += math32.Sqrt(vector.values[i])
}
}
var norm float32
for _, val := range data {
norm += val * val
}
norm = math32.Sqrt(norm)
for i := range data {
data[i] /= norm
}
return &DictionaryCentroidVector{
data: data,
norm: norm,
}
}
func (v *DictionaryCentroidVector) Distance(vector Vector) float32 {
var sum, common float32
if dictVector, isDictVec := vector.(*DictionaryVector); !isDictVec {
panic(fmt.Sprintf("unexpected vector type: %v", reflect.TypeOf(vector)))
} else {
for _, i := range dictVector.indices {
if val, exist := v.data[i]; exist {
sum += val * math32.Sqrt(v.data[i])
common++
}
}
}
return -sum * common / (common + similarityShrink)
}
type VectorIndex interface {
Build()
Search(q Vector, n int, prune0 bool) ([]int32, []float32)
MultiSearch(q Vector, terms []string, n int, prune0 bool) (map[string][]int32, map[string][]float32)
}