bufferedfileadapter.java

用java实现的神经网络bp的核心算法

/*
 * BufferedFileAdapter.java
 *
 * Created on 2007年12月6日, 上午6:47
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

package Compressor;
import java.io.*;
import java.util.*;
/**
 * buffered file adapter.
 * @author yuhui_bear
 */
public class BufferedFileAdapter {
    private FileAdapter source;
    private LinkedList<LinkedList<DoubleBuffer>> filebuf;
    private Iterator<DoubleBuffer> dataIterator;
    private Iterator<LinkedList<DoubleBuffer>> groupIterator;
    private long group=0;
    private long curCnt=0;
    /**
     * Creates a new instance of BufferedFileAdapter
     * @param sfile the file to be buffered and adapted.
     * @param ds the size of the output data array.
     * @param encode TRUE , work in encode mode.
     * @throws java.io.IOException If there is no such file or other errors about I/O system, the IOException will be thrown.
     */
    public BufferedFileAdapter(File sfile, int ds ,boolean encode) throws IOException{
        LinkedList<DoubleBuffer> filebufSubgourp = new LinkedList();
        filebuf = new LinkedList();
        filebuf.add(filebufSubgourp);
        int cnt=0;
        double[] data ;
        try {
            source = new FileAdapter(sfile,ds,encode);
            data = source.nextGroup();
            while(data != null){
                cnt++;
                group++;
                filebufSubgourp.add(new DoubleBuffer(data));
                if(cnt > 4096){
                    //new subgroup.
                    filebufSubgourp = new LinkedList();
                    filebuf.add(filebufSubgourp);
                    cnt=0;
                }
                data = source.nextGroup();
            }
            dataIterator = filebuf.get(0).iterator();
            groupIterator = filebuf.iterator();
        } catch (IOException ex) {
            ex.printStackTrace();
            throw new IOException();
        }              
    }
    /**
     * return how many batches the file divided.
     * @return return how many batches the file divided.
     */
    public int size(){
        return filebuf.size();
    }    
    /**
     * get the size of batch.
     * @return numbers of group included in per batch.
     */
    public int[] subGroupSize(){
        int[] temp = new int[filebuf.size()];
        for (int i =0 ; i< filebuf.size();i++){
            temp[i] = filebuf.get(i).size();
        }
        return temp;
    }
    /**
     * get next group data.
     * @return one group of data , Normalized.
     */
    public double[] nextGroup(){
        if(dataIterator.hasNext()){
            curCnt ++;
            return dataIterator.next().data;
        }else{
            if(groupIterator.hasNext()){
                dataIterator = groupIterator.next().iterator();
                if(dataIterator.hasNext()){
                    curCnt ++;
                    return dataIterator.next().data;
                }   //get data in new group.
            }   //check next gourp.
        }   //search next gourp.                
        return null;
    }
    
    /**
     * reset iterator to the starting point.
     */
    public void resetIterator(){
        groupIterator = filebuf.iterator();
        dataIterator = filebuf.get(0).iterator();            
    }
    /**
     * inqure progress by present.
     * @return int number between 0 ~100
     */
    public int getProgress (){
        return (int)(100 * curCnt / group);
    }
    /**
     * write back data the file.The data will not be instantly writen until buffer managed by JVM was ful.
     * @param toWrite data to be writen.
     * @return -1,write error.
     * -2,close error.
     * 1,work done.
     * 2,close stream succeed by file size.
     */
    public int writeGroup(double[] toWrite){
        return source.writeBack(toWrite);
    }
    /**
     *box of double arrays.
     */
    class DoubleBuffer {
    public double[] data;
    public DoubleBuffer(double[] indouble){
        data =indouble;
    }
}
}