该程序是模拟tensflow游乐场写的，实现了基本的神经网络效果并验证通过，不多废话，上代码。
核心代码在nn.c中，包含激活函数和损失函数，前向传播，反向传播以及更新权重与偏执的函数。
#include <stdint.h>
#include <stdlib.h>
#include <math.h>
#include "config.h"
#include "dataset.h"
#include "nn.h"
int networkShape[] = {2, 8, 8, 8, 8, 8, 8, 1};
NODE **network;
double getOutPut()
{
return network[sizeof(networkShape) / sizeof(int) - 1][0].output;
}
double square(double output, double target)
{
double r = output - target;
return r * r / 2;
}
double squareder(double output, double target)
{
return output - target;
}
double activation(double x)
{
#if ACTIVATIONFUNCTION == RELU
if (x > 0)
{
return x;
}
else
{
return 0;
}
#elif ACTIVATIONFUNCTION == TANH
return tanh(x);
#endif
}
double activationder(double x)
{
#if ACTIVATIONFUNCTION == RELU
if (x > 0)
{
return 1;
}
else
{
return 0;
}
#elif ACTIVATIONFUNCTION == TANH
// tanh的倒数
double y = tanh(x);
return 1 - y * y;
#endif
}
double outlayeractivation(double x)
{
#if OUTLAYERACTIVATIONFUNCTION == TANH
return tanh(x);
#endif
}
double outlayeractivationder(double x)
{
#if OUTLAYERACTIVATIONFUNCTION == TANH
// tanh的倒数
double y = tanh(x);
return 1 - y * y;
#endif
}
void buildNetwork()
{
network = (PPNODE)malloc((sizeof(networkShape) / sizeof(int)) * sizeof(PNODE));
// 输入层
network[0] = (PNODE)malloc(networkShape[0] * sizeof(NODE));
// 隐藏层与输出层
for (int i = 1, leni = sizeof(networkShape) / sizeof(int); i < leni; i++)
{
network[i] = (PNODE)malloc(networkShape[i] * sizeof(NODE));
int prenodeNum = networkShape[i - 1];
for (int j = 0, lenj = networkShape[i]; j < lenj; j++)
{
network[i][j].link = (PLINK)malloc(prenodeNum * sizeof(LINK));
}
}
// 输入层
for (int i = 0; i < networkShape[0]; i++)
{
network[0][i].bias = 0.1;
}
// 隐藏层与输出层
for (int i = 1, leni = sizeof(networkShape) / sizeof(int); i < leni; i++)
{
for (int j = 0, lenj = networkShape[i]; j < lenj; j++)
{
network[i][j].bias = 0.1;
network[i][j].inputDer = 0;
network[i][j].outputDer = 0;
network[i][j].accInputDer = 0;
network[i][j].numAccumulatedDers = 0;
for (int k = 0, lenk = networkShape[i - 1]; k < lenk; k++)
{
network[i][j].link[k].weight = (double)rand() / RAND_MAX - 0.5;
network[i][j].link[k].errorDer = 0;
network[i][j].link[k].accErrorDer = 0;
network[i][j].link[k].numAccumulatedDers = 0;
}
}
}
}
void forwardProp(POINT point)
{
int outlayerNum = sizeof(networkShape) / sizeof(int) - 1; // 输出层所在层
// 输入层
network[0][0].output = point.x;
network[0][1].output = point.y;
// 隐藏层
for (int i = 1, leni = outlayerNum; i < leni; i++)
{
for (int j = 0, lenj = networkShape[i]; j < lenj; j++)
{
network[i][j].totalInput = network[i][j].bias;
for (int k = 0, lenk = networkShape[i - 1]; k < lenk; k++)
{
network[i][j].totalInput += network[i][j].link[k].weight * network[i - 1][k].output;
}
network[i][j].output = activation(network[i][j].totalInput);
}
}
// 输出层
for (int i = 0, leni = networkShape[outlayerNum]; i < leni; i++)
{
network[outlayerNum][i].totalInput = network[outlayerNum][i].bias;
for (int j = 0, lenj = networkShape[outlayerNum - 1]; j < lenj; j++)
{
network[outlayerNum][i].totalInput += network[outlayerNum][i].link[j].weight * network[outlayerNum - 1][j].output;
}
network[outlayerNum][i].output = outlayeractivation(network[outlayerNum][i].totalInput);
}
}
void backProp(POINT point)
{
// 清空所有节点的outputDer
for (int i = 0, leni = sizeof(networkShape) / sizeof(int); i < leni; i++)
{
for (int j = 0; j < networkShape[i]; j++)
{
network[i][j].outputDer = 0;
}
}
int outlayerNum = sizeof(networkShape) / sizeof(int) - 1; // 输出层所在层
// 输出层
for (int i = 0, leni = networkShape[outlayerNum]; i < leni; i++)
{
network[outlayerNum][i].outputDer = squareder(network[outlayerNum][i].output, point.label); // 目标和结果的差距
network[outlayerNum][i].inputDer = network[outlayerNum][i].outputDer * outlayeractivationder(network[outlayerNum][i].totalInput);
network[outlayerNum][i].accInputDer += network[outlayerNum][i].inputDer;
network[outlayerNum][i].numAccumulatedDers++;
for (int j = 0, lenj = networkShape[outlayerNum]; j < lenj; j++)
{
network[outlayerNum][i].link[i].errorDer = network[outlayerNum][i].inputDer * network[outlayerNum - 1][i].output;
network[outlayerNum][i].link[i].accErrorDer += network[outlayerNum][i].link[i].errorDer;
network[outlayerNum][i].link[i].numAccumulatedDers++;
network[outlayerNum - 1][i].outputDer += network[outlayerNum][i].link[i].weight * network[outlayerNum][i].inputDer;
}
}
// 隐藏层
for (int i = outlayerNum; i > 0; i--)
{
for (int j = 0; j < networkShape[i]; j++)
{
network[i][j].inputDer = network[i][j].outputDer * activationder(network[i][j].totalInput);
network[i][j].accInputDer += network[i][j].inputDer;
network[i][j].numAccumulatedDers++;
for (int k = 0; k < networkShape[i - 1]; k++)
{
network[i][j].link[k].errorDer = network[i][j].inputDer * network[i - 1][k].output;
network[i][j].link[k].accErrorDer += network[i][j].link[k].errorDer;
network[i][j].link[k].numAccumulatedDers++;
network[i - 1][k].outputDer += network[i][j].link[k].weight * network[i][j].inputDer;
}
}
}
}
void updateWeights()
{
// 隐藏层与输出层
for (int i = 1; i < sizeof(networkShape) / sizeof(int); i++)
{
for (int j = 0; j < networkShape[i]; j++)
{
if (network[i][j].numAccumulatedDers > 0)
{
network[i][j].bias -= LEARNINGRATE * network[i][j].accInputDer / network[i][j].numAccumulatedDers;
network[i][j].accInputDer = 0;
network[i][j].numAccumulatedDers = 0;
}
for (int k = 0; k < networkShape[i - 1]; k++)
{
if (network[i][j].link[k].numAccumulatedDers > 0)
{
network[i][j].link[k].weight -= LEARNINGRATE * network[i][j].link[k].accErrorDer / network[i][j].link[k].numAccumulatedDers;
network[i][j].link[k].accErrorDer = 0;
network[i][j].link[k].numAccumulatedDers = 0;
}
}
}
}
}对应头文件为nn.h
#ifndef __NN_H__
#define __NN_H__
#include "config.h"
typedef struct LINK
{
double weight;
double errorDer;
double accErrorDer;
int numAccumulatedDers;
} LINK;
typedef LINK *PLINK;
typedef struct NODE
{
double bias;
PLINK link;
double output;
double inputDer;
double outputDer;
double accInputDer;
int numAccumulatedDers;
double totalInput;
} NODE;
typedef NODE *PNODE;
typedef PNODE *PPNODE;
double getOutPut();
double square(double output, double target);
double squareder(double output, double target);
double tanhder(double x); // tanh的倒数
double activation(double x);
double activationder(double x);
double outlayeractivation(double x);
double outlayeractivationder(double x);
void buildNetwork();
void forwardProp(POINT point);
void backProp(POINT point);
void updateWeights();
#endif自动创建与生成训练集与测试集的程序，这里就创建了一个基于半径为5的圆型，圆中间是一部分数据，圆外围是一部分数据。
#include <stdlib.h>
#include <math.h>
#include "config.h"
#include "dataset.h"
POINT points[NUMSAMPLES];
void shuffle()
{
for (int i = 0; i < NUMSAMPLES; i++)
{
int index = i * ((double)rand() / RAND_MAX);
POINT point = points[i];
points[i] = points[index];
points[index] = point;
}
}
// 创建NUMSAMPLES个参数，按照原型来创建
void classifyCircleData()
{
double radius = 5;
// 创建内部圆上的点
for (int i = 0; i < NUMSAMPLES / 2; i++)
{
double r = 0.5 * radius * rand() / RAND_MAX; // 生成随机的半径
double angle = 2.0 * M_PI * rand() / RAND_MAX; // 生成随机的角度
points[i].x = r * cos(angle);
points[i].y = r * sin(angle);
points[i].label = 1;
}
// 创建外部圆上的点
for (int i = NUMSAMPLES / 2; i < NUMSAMPLES; i++)
{
double r = 0.7 * radius + 0.3 * radius * rand() / RAND_MAX; // 生成随机的半径
double angle = 2.0 * M_PI * rand() / RAND_MAX; // 生成随机的角度
points[i].x = r * cos(angle);
points[i].y = r * sin(angle);
points[i].label = -1;
}
shuffle();
}对应头文件为dataset.h
#ifndef __DATASET_H__
#define __DATASET_H__
typedef struct
{
double x;
double y;
double label;
} POINT;
void classifyCircleData();
#endif程序配置部分为config.h，定义了数据集大小，学习率以及batchsize大小，还有激活函数，损失函数等应该选什么。
#ifndef __CONFIG_H__ #define __CONFIG_H__ #define NUMSAMPLES 500 // 创建测试点的数量，其中前一半作为训练集，后一半作为测试集 #define LEARNINGRATE 0.03 #define BATCHSIZE 10 #define ACTIVATIONFUNCTION RELU #define OUTLAYERACTIVATIONFUNCTION TANH #endif
main.c主要是调用上述函数，初始化网络以及数据集，以及训练。
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "config.h"
#include "dataset.h"
#include "nn.h"
extern POINT points[NUMSAMPLES];
double getLoss(int mode) // 0代表训练集，1代表测试集
{
double loss = 0;
if (mode)
{
for (int i = NUMSAMPLES / 2; i < NUMSAMPLES; i++)
{
forwardProp(points[i]);
loss += square(getOutPut(), points[i].label);
}
}
else
{
for (int i = 0; i < NUMSAMPLES / 2; i++)
{
forwardProp(points[i]);
loss += square(getOutPut(), points[i].label);
}
}
return loss / (NUMSAMPLES / 2);
}
void training()
{
for (int i = 0; i < NUMSAMPLES / 2; i++)
{
forwardProp(points[i]);
backProp(points[i]);
if ((i + 1) % BATCHSIZE == 0)
{
updateWeights();
}
}
double lossTrain = getLoss(0);
double lossTest = getLoss(1);
printf("lossTrain:%f,lossTest:%f\n", lossTrain, lossTest);
}
int main(int argc, char **argv)
{
srand((unsigned)time(NULL));
classifyCircleData();
buildNetwork();
double lossTrain = getLoss(0);
double lossTest = getLoss(1);
printf("lossTrain:%f,lossTest:%f\n", lossTrain, lossTest);
for (int i = 0; i < 100; i++)
{
training();
}
return 0;
}代码完整地址为：传送门
后期可能会根据我学习的深入继续更新这份代码，就不另行通知了。
文章作者：沃航科技
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