gotensor/examples/advanced_optimizer/advanced_optimizer_example.go

package main

import (
	"fmt"

	"git.kingecg.top/kingecg/gotensor"
)

// LinearLayer 是一个简单的线性层实现
type LinearLayer struct {
	Weight *gotensor.Tensor
	Bias   *gotensor.Tensor
}

// NewLinearLayer 创建一个新的线性层
func NewLinearLayer(inputSize, outputSize int) *LinearLayer {
	// 初始化权重和偏置
	weight, _ := gotensor.NewTensor([]float64{
		0.1, 0.2,
		0.3, 0.4,
	}, []int{outputSize, inputSize})

	bias, _ := gotensor.NewTensor([]float64{0.1, 0.1}, []int{outputSize})

	return &LinearLayer{
		Weight: weight,
		Bias:   bias,
	}
}

func (l *LinearLayer) Forward(inputs *gotensor.Tensor) (*gotensor.Tensor, error) {
	// 执行线性变换: output = inputs * weight^T + bias
	weightTransposed, err := l.Weight.Data.Transpose()
	if err != nil {
		return nil, err
	}

	// 创建转置后的权重张量
	weightTransposedTensor := &gotensor.Tensor{
		Data: weightTransposed,
		Grad: must(gotensor.NewZeros(l.Weight.Shape())),
	}

	mulResult, err := inputs.MatMul(weightTransposedTensor)
	if err != nil {
		return nil, err
	}

	output, err := mulResult.Add(l.Bias)
	if err != nil {
		return nil, err
	}

	return output, nil
}

func (l *LinearLayer) Parameters() []*gotensor.Tensor {
	return []*gotensor.Tensor{l.Weight, l.Bias}
}

func (l *LinearLayer) ZeroGrad() {
	l.Weight.ZeroGrad()
	l.Bias.ZeroGrad()
}

// SimpleModel 是一个简单的模型实现
type SimpleModel struct {
	Layer *LinearLayer
}

func (m *SimpleModel) Forward(inputs *gotensor.Tensor) (*gotensor.Tensor, error) {
	return m.Layer.Forward(inputs)
}

func (m *SimpleModel) Parameters() []*gotensor.Tensor {
	return m.Layer.Parameters()
}

func (m *SimpleModel) ZeroGrad() {
	m.Layer.ZeroGrad()
}

// must 是一个辅助函数，用于处理可能的错误
func must(t *gotensor.Tensor, err error) *gotensor.Tensor {
	if err != nil {
		panic(err)
	}
	return t
}

func main() {
	fmt.Println("Gotensor Advanced Optimizer Example")

	// 创建模型
	model := &SimpleModel{
		Layer: NewLinearLayer(2, 2), // 2输入，2输出
	}

	fmt.Println("比较不同优化器的性能:")

	// 准备训练数据 (简单的线性回归问题)
	trainInputs := []*gotensor.Tensor{
		must(gotensor.NewTensor([]float64{1, 0}, []int{2})),
		must(gotensor.NewTensor([]float64{0, 1}, []int{2})),
		must(gotensor.NewTensor([]float64{1, 1}, []int{2})),
		must(gotensor.NewTensor([]float64{0, 0}, []int{2})),
	}

	trainTargets := []*gotensor.Tensor{
		must(gotensor.NewTensor([]float64{2, 0}, []int{2})),
		must(gotensor.NewTensor([]float64{0, 2}, []int{2})),
		must(gotensor.NewTensor([]float64{2, 2}, []int{2})),
		must(gotensor.NewTensor([]float64{0, 0}, []int{2})),
	}

	// 定义损失函数 (MSE)
	lossFn := func(output, target *gotensor.Tensor) *gotensor.Tensor {
		// 计算均方误差
		diff, _ := output.Sub(target)
		squared, _ := diff.Mul(diff)
		sum, _ := squared.Sum()
		size := float64(output.Size())
		result, _ := sum.DivScalar(size)
		return result
	}

	// 测试SGD优化器
	fmt.Println("\n1. 使用SGD优化器训练:")
	sgdModel := &SimpleModel{
		Layer: NewLinearLayer(2, 2),
	}
	sgdOptimizer := gotensor.NewSGD(sgdModel.Parameters(), 0.1)
	sgdTrainer := gotensor.NewTrainer(sgdModel, sgdOptimizer)

	sgdInitialLoss, _ := sgdTrainer.Evaluate(trainInputs, trainTargets, lossFn)
	fmt.Printf("初始损失: %.6f\n", sgdInitialLoss)

	err := sgdTrainer.Train(trainInputs, trainTargets, 100, lossFn, false)
	if err != nil {
		fmt.Printf("SGD训练过程中出现错误: %v\n", err)
		return
	}

	sgdFinalLoss, _ := sgdTrainer.Evaluate(trainInputs, trainTargets, lossFn)
	fmt.Printf("SGD最终损失: %.6f\n", sgdFinalLoss)

	// 测试Adam优化器
	fmt.Println("\n2. 使用Adam优化器训练:")
	adamModel := &SimpleModel{
		Layer: NewLinearLayer(2, 2),
	}
	adamOptimizer := gotensor.NewAdam(adamModel.Parameters(), 0.01, 0.9, 0.999, 1e-8)
	adamTrainer := gotensor.NewTrainer(adamModel, adamOptimizer)

	adamInitialLoss, _ := adamTrainer.Evaluate(trainInputs, trainTargets, lossFn)
	fmt.Printf("初始损失: %.6f\n", adamInitialLoss)

	err = adamTrainer.Train(trainInputs, trainTargets, 100, lossFn, false)
	if err != nil {
		fmt.Printf("Adam训练过程中出现错误: %v\n", err)
		return
	}

	adamFinalLoss, _ := adamTrainer.Evaluate(trainInputs, trainTargets, lossFn)
	fmt.Printf("Adam最终损失: %.6f\n", adamFinalLoss)

	// 比较两个模型的预测结果
	fmt.Println("\n比较两个模型的预测结果:")
	testInput := must(gotensor.NewTensor([]float64{0.5, 0.5}, []int{2}))

	sgdOutput, _ := sgdModel.Forward(testInput)
	adamOutput, _ := adamModel.Forward(testInput)

	sgdOut0, _ := sgdOutput.Data.Get(0)
	sgdOut1, _ := sgdOutput.Data.Get(1)
	adamOut0, _ := adamOutput.Data.Get(0)
	adamOut1, _ := adamOutput.Data.Get(1)

	fmt.Printf("输入: [0.5, 0.5]\n")
	fmt.Printf("SGD输出: [%.6f, %.6f]\n", sgdOut0, sgdOut1)
	fmt.Printf("Adam输出: [%.6f, %.6f]\n", adamOut0, adamOut1)

	// 演示手动使用优化器
	fmt.Println("\n3. 演示手动使用优化器:")
	manualModel := &SimpleModel{
		Layer: NewLinearLayer(2, 2),
	}
	manualOptimizer := gotensor.NewAdam(manualModel.Parameters(), 0.01, 0.9, 0.999, 1e-8)

	// 执行几个训练步骤
	for step := 0; step < 5; step++ {
		totalLoss := 0.0
		for i := 0; i < len(trainInputs); i++ {
			// 前向传播
			output, err := manualModel.Forward(trainInputs[i])
			if err != nil {
				fmt.Printf("前向传播错误: %v\n", err)
				return
			}

			// 计算损失
			loss := lossFn(output, trainTargets[i])
			lossVal, _ := loss.Data.Get(0)
			totalLoss += lossVal

			// 反向传播
			loss.Backward()

			// 更新参数
			manualOptimizer.Step()

			// 清空梯度
			manualOptimizer.ZeroGrad()
		}

		avgLoss := totalLoss / float64(len(trainInputs))
		fmt.Printf("步骤 %d, 平均损失: %.6f\n", step+1, avgLoss)
	}

	fmt.Println("\n优化器示例完成!")
}