java回归中的残差平方和的均值

你的名字 2022-07-12 01:11 178阅读 0赞

以下，是我在写一个算法时中的一小部分，程序给了一个简单的算例。

计算**残差平方和的均值**。  
以下是残差平方和公式。  
![这里写图片描述][SouthEast]

package sampling.method;
    
    import java.util.HashMap;
    import java.util.Map;
    import org.apache.commons.math3.linear.Array2DRowRealMatrix;
    import org.apache.commons.math3.linear.RealMatrix;
    public class Test {
    
        public static void main(String[] args) {
            Map<Integer,RealMatrix > ymatrix=new HashMap<Integer,RealMatrix >();
            double[][] y1={
       {
       1,2,3,4}};
            RealMatrix y1matrix = new Array2DRowRealMatrix(y1);
            double[][] y2={
       {
       2,3,3,5,7}};
            RealMatrix y2matrix = new Array2DRowRealMatrix(y2);
            //这里的1和2分别表示类别
            ymatrix.put(1, y1matrix);
            ymatrix.put(2, y2matrix);
            //
            Map<Integer,RealMatrix > xMatrixList=new  HashMap<Integer,RealMatrix >();
            double[][] x1={
       {
       1,2},{
       3,4},{
       2,4},{
       2,4}};
            double[][] x2={
       {
       1,2},{
       3,4},{
       0,0},{
       5,4},{
       2,6}};
            RealMatrix x1mat = new Array2DRowRealMatrix(x1);
            RealMatrix x2mat = new Array2DRowRealMatrix(x2);
            xMatrixList.put(1, x1mat);
            xMatrixList.put(2, x2mat);
            //
            Map<Integer,RealMatrix > wMatrixList=new  HashMap<Integer,RealMatrix >();
            double[][] w1={
       {
       1,2}};
            double[][] w2={
       {
       2,3}};
            RealMatrix w1mat = new Array2DRowRealMatrix(w1);
            RealMatrix w2mat = new Array2DRowRealMatrix(w2);
            wMatrixList.put(1, w1mat);
            wMatrixList.put(2, w2mat);
            double sum=0.0;
            int dimension=0;
            for( int itemnumber : ymatrix.keySet() ){
                RealMatrix yscore=ymatrix.get(itemnumber) ;
                dimension+=yscore.getColumnDimension();
                RealMatrix wxscore=wMatrixList.get(itemnumber).multiply(xMatrixList.get(itemnumber).transpose()) ;
                RealMatrix ysbuwxscore =yscore.add(wxscore.scalarMultiply(-1.0));
                System.out.println(yscore.add(wxscore.scalarMultiply(-1.0)));
                System.out.println(ysbuwxscore.multiply(ysbuwxscore.transpose()));
                sum+=sumarray(ysbuwxscore.multiply(ysbuwxscore.transpose()));
    
            }
            System.out.println("残差平方和均值为："+sum/dimension);
        }
        private static double sumarray(RealMatrix a){
            double[][] arr=a.getData();
            double sum = 0.0; 
            for (int i = 0; i < arr.length; i++) {  
                for (int j = 0; j < arr[i].length; j++) {  
                    sum += arr[i][j];  
                }  
            } 
            return sum;
        }
    }

![这里写图片描述][SouthEast 1]

[SouthEast]: /images/20220711/93b03a23effa4be8b7c0612118f41073.png
[SouthEast 1]: /images/20220711/420c61aea8024c1ca4a3fafeed3bf70d.png