bp神经网络对数据分类的实现（java代码，iris测试数据）

package zxz; import java.io.File; import java.io.FileNotFoundException; import java.util.HashMap; import java.util.Scanner; public class BPNN { /** * @param args */ int inputnodenum=4; int hidennodenum=3; int outputnodenum=3; int maxstep=5000; int step; double theta=0.5; double lambda=1.0; double alpha=0.01; double eta=0.5; double v[][]; double w[][]; double inputdata[]; double hidendata[]; double outputdata[]; double rightoutput[]; double deltav[][][]; double deltaw[][][]; HashMap<String, Integer> map; String [] classname; void init() { v=new double[inputnodenum][hidennodenum]; w=new double[hidennodenum][outputnodenum]; deltav=new double[maxstep+1][inputnodenum][hidennodenum];//0 deltaw=new double[maxstep+1][hidennodenum][outputnodenum]; inputdata=new double[inputnodenum]; hidendata=new double[hidennodenum]; outputdata=new double[outputnodenum]; rightoutput=new double[outputnodenum]; map=new HashMap<String, Integer>(); classname=new String[]{"Iris-setosa","Iris-versicolor","Iris-virginica"}; for(int i=0;i<3;++i) map.put(classname[i], i); for(int i=0;i<inputnodenum;++i) { for(int j=0;j<hidennodenum;++j) { v[i][j]=Math.random(); } } for(int i=0;i<hidennodenum;++i) { for(int j=0;j<outputnodenum;++j) { w[i][j]=Math.random(); } } } void showweight() { System.out.println("V:"); for(int i=0;i<inputnodenum;++i) { for(int j=0;j<hidennodenum;++j) { System.out.print(v[i][j]+" "); } System.out.println(); } System.out.println("W:"); for(int i=0;i<hidennodenum;++i) { for(int j=0;j<outputnodenum;++j) { System.out.print(w[i][j]+" "); } System.out.println(); } System.out.println(); } double sigmoid(double x) { return 1/(1+Math.exp(-x)); } void train() throws FileNotFoundException { String input=""; String inputline; String tmpdata[]; Scanner jin; jin = new Scanner(new File("iris/bezdekIris.data")); while(jin.hasNext()) { inputline=jin.nextLine(); input+=inputline+"\r\n"; } for(step=1;step<=maxstep;++step) { jin = new Scanner(input); while(jin.hasNext()) { inputline=jin.next(); tmpdata=inputline.split(","); for(int i=0;i<inputnodenum;++i) { inputdata[i]=Double.parseDouble(tmpdata[i]); } for(int i=0;i<3;++i) { if(i==map.get(tmpdata[inputnodenum])) rightoutput[i]=1; else rightoutput[i]=0; } for(int j=0;j<hidennodenum;++j)// { hidendata[j]=-theta; for(int i=0;i<inputnodenum;++i) hidendata[j]+=v[i][j]*inputdata[i]; hidendata[j]=sigmoid(hidendata[j]); } for(int k=0;k<outputnodenum;++k)// { outputdata[k]=-theta; for(int j=0;j<hidennodenum;++j) outputdata[k]+=w[j][k]*hidendata[j]; outputdata[k]=sigmoid(outputdata[k]); } for(int k=0;k<outputnodenum;++k)// { for(int j=0;j<hidennodenum;++j)// deltaw[step][j][k]=-eta*(-(rightoutput[k]-outputdata[k]))*(1-outputdata[k])*outputdata[k]*hidendata[j]; } for(int j=0;j<hidennodenum;++j) { for(int i=0;i<inputnodenum;++i) { double sum=0; for(int k=0;k<outputnodenum;++k) sum+=-(rightoutput[k]-outputdata[k])*(1-outputdata[k])*outputdata[k]*w[j][k]; deltav[step][i][j]=-eta*sum*(1-hidendata[j])*hidendata[j]*inputdata[i]; } } for(int k=0;k<outputnodenum;++k)// { for(int j=0;j<hidennodenum;++j) w[j][k]+=deltaw[step][j][k]+alpha*deltaw[step-1][j][k]; } for(int j=0;j<hidennodenum;++j) { for(int i=0;i<inputnodenum;++i) v[i][j]+=deltav[step][i][j]+alpha*deltav[step-1][i][j]; } } } } void test() throws FileNotFoundException { int total=0; int right=0; String inputline; String tmpdata[]; Scanner jin = new Scanner(new File("iris/iris.data")); while(jin.hasNext()) { inputline=jin.next(); tmpdata=inputline.split(","); for(int i=0;i<inputnodenum;++i) { inputdata[i]=Double.parseDouble(tmpdata[i]); } for(int j=0;j<hidennodenum;++j)// { hidendata[j]=-theta; for(int i=0;i<inputnodenum;++i) hidendata[j]+=v[i][j]*inputdata[i]; hidendata[j]=sigmoid(hidendata[j]); } for(int k=0;k<outputnodenum;++k)// { outputdata[k]=-theta; for(int j=0;j<hidennodenum;++j) outputdata[k]+=w[j][k]*hidendata[j]; outputdata[k]=sigmoid(outputdata[k]); } int classid=0; for(int k=1;k<outputnodenum;++k) { if(outputdata[classid]<outputdata[k]) classid=k; } System.out.print(inputline+" "+classname[classid]+" "); if(classid==map.get(tmpdata[inputnodenum])) { System.out.println("right"); right++; } else System.out.println("wrong"); total++; } System.out.println(); System.out.println("The total number of test data:"+total); System.out.println("The right number of test data:"+right); System.out.println("The right ratio: of test data:"+(double)right/total); } void run() throws FileNotFoundException { long t1=System.currentTimeMillis(); init(); train(); test(); System.out.println("Runtime:"+(System.currentTimeMillis()-t1)+"ms"); } }