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// 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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} |