神经网络与深度学习(二)cpp-c++BP神经网络

读到作者用java实现的神经网络解决异或等问题

以下为c++实现版本

接口略有不同

具体关键的更新的证明详见机器学习或大牛博客

有一个关键的地方是 权值的初始化

原本是都初始化0 但是楼主也意识到 这样无论怎样更新 隐层不同神经元对应输入层同一神经元的权值都相同 相当于 仍然用一个线性函数划分 不可线性划分的区域

思考良久就初始化为随机数了 然而不行 后来看了别人的初始化 发现了这个

//关键的初始化权值		for (int i = 0; i < lastlayerneunum; ++i)			this->Last_weight[i] = (2.0*(double)rand() / RAND_MAX) - 1;改了一下 瞬间问题都没了 也很神奇  至于原因  楼主开学要回去问学长  有知道的大神也请赐教
一下为代码  如有bug 欢迎指正
楼主有些懒 成员函数的实现都在类内部了 有点难看 还请别介意
TransferFunc.h  激励函数类及类型的定义
//TransferFunc.h//created by WK#ifndef TRANSFERFUNC_H#define TRANSFERFUNC_H#include <cmath>enum Functypes{	FUNCTYPE_TANH,	FUNCTYPE_STEP,	FUNCTYPE_LINEAR,	FUNCTYPE_SIGMOID};class Function{PRivate:	double Step(double input)	{		if (input < 0)			return 0;		else			return 1;	}	double Linear(double input)	{		return input;	}	double Sigmoid(double input)	{		return 1.0 / (1.0 + exp(-1.0*input));	}public:	double GetResult(int funcType, double input)	{		switch (funcType)		{		case FUNCTYPE_TANH:			return tanh(input);		case FUNCTYPE_STEP:			return Step(input);		case FUNCTYPE_LINEAR:			return Linear(input);		case FUNCTYPE_SIGMOID:			return Sigmoid(input);		default:			return input;		}	}};#endif // !TRANSFERFUNC_HDataSet.h 数据集类型
//DateSet.h//created by WK#ifndef DATASET_H#define DATASET_H#include <vector>using namespace std;//数据集class DataSet{private:	int					InputNum;	int					OutputNum;	vector<double*>		DataMap;public:	DataSet(int inputnum, int outputnum)	{		this->InputNum = inputnum;		this->OutputNum = outputnum;	}	void AddRow(double *inputArray, double *outputArray)	{		double *data = new double[this->InputNum + this->OutputNum];		for (int i = 0; i<this->InputNum; ++i)		{			data[i] = inputArray[i];		}		for (int i = 0; i<this->OutputNum; ++i)		{			data[InputNum + i] = outputArray[i];		}		this->DataMap.push_back(data);	}	int GetInputNum()	{		return this->InputNum;	}	int GetOutputNum()	{		return this->OutputNum;	}	int GetRows()	{		return DataMap.size();	}	vector<double*> GetDataMap()	{		return DataMap;	} };#endif // !DATASET_H
MultiLayerPerceptron.cpp神经元定义以及单隐层神经网络定义 以及 异或问题的解决
#include <vector>#include <iostream>#include "TransferFunc.h"#include "DataSet.h"#include <time.h>#include <cstdlib>using namespace std;#define WINITVALUE 0.001#define TINITVALUE 0//神经元class Neuron{private:	double				Input;	double				Output;	double				Threshold;	double				*Last_weight;			//神经元维护后向的权重	int					LastLayerNeuNum;	int					TransferFunctionType;	Function			Transferfunction;public:	Neuron(double threshold, int lastlayerneunum, int funcType)	{		this->Input					=	0;		this->Output				=	0;		this->Threshold				=	threshold;		this->LastLayerNeuNum		=	lastlayerneunum;		this->TransferFunctionType	=	funcType;		this->Last_weight			=	new double[lastlayerneunum];		//关键的初始化权值		for (int i = 0; i < lastlayerneunum; ++i)			this->Last_weight[i] = (2.0*(double)rand() / RAND_MAX) - 1;			}	void SetInput(double input)	{		this->Input = input;	}	double GetOutput()	{		this->Output = Transferfunction.GetResult(this->TransferFunctionType, this->Input - this->Threshold);		return this->Output;	}	double* GetThreshold()	{		return &this->Threshold;	}	double *GetWeight()	{		return this->Last_weight;	}	void SetFuncType(int functype)	{		this->TransferFunctionType = functype;	}};//多层感知机class MultiLayerPerceptron{private:	int			OutTransfetFunctionType;	int			HideTransfetFunctionType;	int			InTransfetFunctionType;	int			InLayerNeuNum;	int			HideLayerNeuNum;	int			OutLayerNeuNum;	double		Speed;	Neuron		**InputNeurons;	Neuron		**OutputNeurons;	Neuron		**HidenNeurons;public:	MultiLayerPerceptron(int intransferfunctiontype, int inLayerNeuNum, int hidetransferfunctiontype, int hideLayerNeuNum, int outtransferfunctiontype, int outLayerNeuNum, double speed)	{		this->InTransfetFunctionType	=	intransferfunctiontype;		this->HideTransfetFunctionType	=	hidetransferfunctiontype;		this->OutTransfetFunctionType	=	outtransferfunctiontype;		this->InLayerNeuNum				=	inLayerNeuNum;		this->HideLayerNeuNum			=	hideLayerNeuNum;		this->OutLayerNeuNum			=	outLayerNeuNum;		this->Speed						=	speed;		this->InputNeurons	= (Neuron**)new void*[inLayerNeuNum];		for (int i = 0; i < inLayerNeuNum; ++i)			this->InputNeurons[i] = new Neuron(TINITVALUE, 0, intransferfunctiontype);		this->HidenNeurons	= (Neuron**)new void*[hideLayerNeuNum];		for (int i = 0; i < hideLayerNeuNum; ++i)			this->HidenNeurons[i] = new Neuron(TINITVALUE, inLayerNeuNum, hidetransferfunctiontype);		this->OutputNeurons = (Neuron**)new void*[outLayerNeuNum];		for (int i = 0; i < outLayerNeuNum; ++i)			this->OutputNeurons[i] = new Neuron(TINITVALUE, hideLayerNeuNum, outtransferfunctiontype);	}	//获取正向的输出	void GetOutput(double *output)	{		double sum;		for (int i = 0; i < this->HideLayerNeuNum; ++i)		{			sum = 0;			for (int j = 0; j < this->InLayerNeuNum; ++j)				sum += this->HidenNeurons[i]->GetWeight()[j] * this->InputNeurons[j]->GetOutput();			this->HidenNeurons[i]->SetInput(sum);		}		for (int i = 0; i < this->OutLayerNeuNum; ++i)		{			sum = 0;			for (int j = 0; j < this->HideLayerNeuNum; ++j)				sum += this->OutputNeurons[i]->GetWeight()[j] * this->HidenNeurons[j]->GetOutput();			this->OutputNeurons[i]->SetInput(sum);			output[i] = this->OutputNeurons[i]->GetOutput();		}	}	//学习所有数据一次更新权值以及阈值	void Learn(DataSet *trainingSet)	{		double *expect;		double *data;		double *output = new double[this->OutLayerNeuNum];		for (int i = 0; i < trainingSet->GetRows(); ++i)		{			data	= trainingSet->GetDataMap()[i];			expect	= data + trainingSet->GetInputNum();			for (int j = 0; j < trainingSet->GetInputNum(); ++j)				this->InputNeurons[j]->SetInput(data[j]);			this->GetOutput(output);			//更改隐藏层到输出层权重以及阈值			//更新公式详见机器学习			for (int j = 0; j < this->OutLayerNeuNum; ++j)			{						double delta = this->Speed * output[j] * (1 - output[j]) * (expect[j] - output[j]);				for (int k = 0; k < this->HideLayerNeuNum; ++k)					this->OutputNeurons[j]->GetWeight()[k] += (delta * this->HidenNeurons[k]->GetOutput());				*this->OutputNeurons[j]->GetThreshold() -= delta;			}			//更改输入层到隐藏层的权重以及阈值			//更新公式详见机器学习			for (int j = 0; j < this->HideLayerNeuNum; ++j)			{				double t = 0;				for (int k = 0; k < this->OutLayerNeuNum; ++k)					t += (this->OutputNeurons[k]->GetWeight()[j] * output[k] * (1 - output[k])*(expect[k] - output[k]));				double delta = this->HidenNeurons[j]->GetOutput() * (1 - this->HidenNeurons[j]->GetOutput()) * t;				for (int k = 0; k < this->InLayerNeuNum; ++k)					this->HidenNeurons[j]->GetWeight()[k] += (this->Speed * this->InputNeurons[k]->GetOutput() * delta);				*this->HidenNeurons[j]->GetThreshold() -= (this->Speed * delta);			}		}	}	void Test(DataSet *trainingSet)	{		double *output = new double[this->OutLayerNeuNum];		double *expect = new double[this->OutLayerNeuNum];				for (int i = 0; i < trainingSet->GetRows(); ++i)		{			for (int j = 0; j < trainingSet->GetInputNum(); ++j)				this->InputNeurons[j]->SetInput(trainingSet->GetDataMap()[i][j]);			this->GetOutput(output);			for (int j = 0; j < trainingSet->GetOutputNum(); ++j)			{				cout << "output: ";				cout << output[j] << "/t";				cout << "expect: ";				cout << trainingSet->GetDataMap()[i][trainingSet->GetInputNum()+j]<<"/t";			}			cout << endl;		} 		cout << endl;		cout << "in to hide W:" << endl;		for (int i = 0; i < this->HideLayerNeuNum; ++i)		{			for (int j = 0; j < this->InLayerNeuNum; ++j)			{				cout << this->HidenNeurons[i]->GetWeight()[j] << "  ";			}			cout << endl;		}		cout << endl;		cout << "hide to out W:" << endl;		for (int i = 0; i < this->OutLayerNeuNum; ++i)		{			for (int j = 0; j < this->HideLayerNeuNum; ++j)			{				cout << this->OutputNeurons[i]->GetWeight()[j] << "  ";			}			cout << endl;		}	}};int main(){	DataSet *trainingSet = new DataSet(2, 1);	trainingSet->AddRow(new double[2]{ 1,1 }, new double[1]{ 0 });	trainingSet->AddRow(new double[2]{ 1,0 }, new double[1]{ 1 });	trainingSet->AddRow(new double[2]{ 0,1 }, new double[1]{ 1 });	trainingSet->AddRow(new double[2]{ 0,0 }, new double[1]{ 0 });	//层激励函数类型 神经元个数... 学习速率	MultiLayerPerceptron *m = new MultiLayerPerceptron(FUNCTYPE_LINEAR, 2, FUNCTYPE_SIGMOID, 5, FUNCTYPE_SIGMOID, 1, 0.9);	//学习1000次	for (int i = 0; i < 10000; ++i)		m->Learn(trainingSet);	m->Test(trainingSet);		system("pause");	return 0;}