BP算法java实现（java bpm是什么意思）

陈濂

2017-10-16

import java.util.Random;

public class BpDeep{

public double[][] layer;//神经网络各层节点

public double[][] layerErr;//神经网络各节点误差

public double[][][] layer_weight;//各层节点权重

public double[][][] layer_weight_delta;//各层节点权重动量

public double mobp;//动量系数

public double rate;//学习系数

public BpDeep(int[] layernum, double rate, double mobp){

this.mobp = mobp;

this.rate = rate;

layer = new double[layernum.length][];

layerErr = new double[layernum.length][];

layer_weight = new double[layernum.length][][];

layer_weight_delta = new double[layernum.length][][];

Random random = new Random();

for(int l=0;l<layernum.length;l++){

layer[l]=new double[layernum[l]];

layerErr[l]=new double[layernum[l]];

if(l+1<layernum.length){

layer_weight[l]=new double[layernum[l]+1][layernum[l+1]];

layer_weight_delta[l]=new double[layernum[l]+1][layernum[l+1]];

for(int j=0;j<layernum[l]+1;j++)

for(int i=0;i<layernum[l+1];i++)

layer_weight[l][j][i]=random.nextDouble();//随机初始化权重

}

}

}

//逐层向前计算输出

public double[] computeOut(double[] in){

for(int l=1;l<layer.length;l++){

for(int j=0;j<layer[l].length;j++){

double z=layer_weight[l-1][layer[l-1].length][j];

for(int i=0;i<layer[l-1].length;i++){

layer[l-1][i]=l==1?in[i]:layer[l-1][i];

z+=layer_weight[l-1][i][j]*layer[l-1][i];

}

layer[l][j]=1/(1+Math.exp(-z));

}

}

return layer[layer.length-1];

}

//逐层反向计算误差并修改权重

public void updateWeight(double[] tar){

int l=layer.length-1;

for(int j=0;j<layerErr[l].length;j++)

layerErr[l][j]=layer[l][j]*(1-layer[l][j])*(tar[j]-layer[l][j]);

while(l-->0){

for(int j=0;j<layerErr[l].length;j++){

double z = 0.0;

for(int i=0;i<layerErr[l+1].length;i++){

z=z+l>0?layerErr[l+1][i]*layer_weight[l][j][i]:0;

layer_weight_delta[l][j][i]= mobp*layer_weight_delta[l][j][i]+rate*layerErr[l+1][i]*layer[l][j];//隐含层动量调整

layer_weight[l][j][i]+=layer_weight_delta[l][j][i];//隐含层权重调整

if(j==layerErr[l].length-1){

layer_weight_delta[l][j+1][i]= mobp*layer_weight_delta[l][j+1][i]+rate*layerErr[l+1][i];//截距动量调整

layer_weight[l][j+1][i]+=layer_weight_delta[l][j+1][i];//截距权重调整

}

}

layerErr[l][j]=z*layer[l][j]*(1-layer[l][j]);//记录误差

}

}

}

public void train(double[] in, double[] tar){

double[] out = computeOut(in);

updateWeight(tar);

}

}