init

pkg/util/vector/vector.go

@@ -0,0 +1,53 @@
+// Copyright (C) 2025 wangyusong
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+package vector
+
+import (
+	"math"
+)
+
+func Quantize(vec []float32) (quantized []int8, min, scale float32) {
+	// Find the minimum and maximum values.
+	min, max := float32(math.MaxFloat32), float32(-math.MaxFloat32)
+	for _, v := range vec {
+		if v < min {
+			min = v
+		}
+		if v > max {
+			max = v
+		}
+	}
+
+	// Calculate the quantization scale.
+	scale = float32(255) / (max - min)
+
+	// Quantize the data.
+	quantized = make([]int8, len(vec))
+	for i, v := range vec {
+		quantized[i] = int8(math.Round(float64((v-min)*scale - 128)))
+	}
+
+	return quantized, min, scale
+}
+
+func Dequantize(quantized []int8, min, scale float32) []float32 {
+	vec := make([]float32, len(quantized))
+	for i, v := range quantized {
+		vec[i] = (float32(v)+128)/scale + min
+	}
+
+	return vec
+}

pkg/util/vector/vector_test.go

@@ -0,0 +1,99 @@
+// Copyright (C) 2025 wangyusong
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+package vector
+
+import (
+	"testing"
+
+	. "github.com/onsi/gomega"
+
+	"github.com/glidea/zenfeed/pkg/test"
+)
+
+func TestQuantizeDequantize(t *testing.T) {
+	RegisterTestingT(t)
+
+	type givenDetail struct{}
+	type whenDetail struct {
+		vector []float32
+	}
+	type thenExpected struct {
+		maxError float32
+	}
+
+	tests := []test.Case[givenDetail, whenDetail, thenExpected]{
+		{
+			Scenario: "Quantize and dequantize unit vector",
+			When:     "quantizing and then dequantizing a vector with values between 0 and 1",
+			Then:     "should return vector close to the original with small error",
+			WhenDetail: whenDetail{
+				vector: []float32{0.1, 0.5, 0.9, 0.3},
+			},
+			ThenExpected: thenExpected{
+				maxError: 0.01,
+			},
+		},
+		{
+			Scenario: "Quantize and dequantize vector with negative values",
+			When:     "quantizing and then dequantizing a vector with negative values",
+			Then:     "should return vector close to the original with small error",
+			WhenDetail: whenDetail{
+				vector: []float32{-1.0, -0.5, 0.0, 0.5, 1.0},
+			},
+			ThenExpected: thenExpected{
+				maxError: 0.01,
+			},
+		},
+		{
+			Scenario: "Quantize and dequantize large range vector",
+			When:     "quantizing and then dequantizing a vector with large range of values",
+			Then:     "should return vector close to the original with acceptable error",
+			WhenDetail: whenDetail{
+				vector: []float32{-100, -50, 0, 50, 100},
+			},
+			ThenExpected: thenExpected{
+				maxError: 1.5,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.Scenario, func(t *testing.T) {
+			// When.
+			quantized, min, scale := Quantize(tt.WhenDetail.vector)
+			dequantized := Dequantize(quantized, min, scale)
+
+			// Then.
+			Expect(len(dequantized)).To(Equal(len(tt.WhenDetail.vector)))
+
+			maxError := float32(0)
+
+			for i := range tt.WhenDetail.vector {
+				error := float32(0)
+				if tt.WhenDetail.vector[i] > dequantized[i] {
+					error = tt.WhenDetail.vector[i] - dequantized[i]
+				} else {
+					error = dequantized[i] - tt.WhenDetail.vector[i]
+				}
+				if error > maxError {
+					maxError = error
+				}
+			}
+
+			Expect(maxError).To(BeNumerically("<=", tt.ThenExpected.maxError))
+		})
+	}
+}