62 lines
1.5 KiB
Go
62 lines
1.5 KiB
Go
// Copyright 2023 The casbin Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package object
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import "math"
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func dot(vec1, vec2 []float32) float32 {
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if len(vec1) != len(vec2) {
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panic("Vector lengths do not match")
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}
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dotProduct := float32(0.0)
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for i := range vec1 {
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dotProduct += vec1[i] * vec2[i]
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}
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return dotProduct
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}
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func norm(vec []float32) float32 {
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normSquared := float32(0.0)
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for _, val := range vec {
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normSquared += val * val
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}
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return float32(math.Sqrt(float64(normSquared)))
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}
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func cosineSimilarity(vec1, vec2 []float32, vec1Norm float32) float32 {
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dotProduct := dot(vec1, vec2)
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vec2Norm := norm(vec2)
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if vec2Norm == 0 {
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return 0.0
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}
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return dotProduct / (vec1Norm * vec2Norm)
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}
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func getNearestVectorIndex(target []float32, vectors [][]float32) int {
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targetNorm := norm(target)
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var res int
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max := float32(-1.0)
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for i, vector := range vectors {
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similarity := cosineSimilarity(target, vector, targetNorm)
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if similarity > max {
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max = similarity
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res = i
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}
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}
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return res
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}
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