Question

我正在尝试从文本文件创建矩阵。问题是，当缓冲读取器函数readline（）完成解析第一行文件时，它会到达第二行，但是它将其读为空，而不是。

void covar()
    {
        double [][]covar=new double[10][5];
        int i=0;
        int j=0;
        try
        {
            FileInputStream fstream = new FileInputStream("class 1\\feature_vector.txt");
            DataInputStream in = new DataInputStream(fstream);
            BufferedReader br = new BufferedReader(new InputStreamReader(in));
            String input;

            while((input=br.readLine())!= null)
            {               
                String [] temp=input.split(",");
                //System.out.println(input.split(",").length);
                covar[i][j]= new Double(temp[0]);
                covar[i+1][j]=new Double(temp[1]);
                covar[i+2][j]=new Double(temp[2]);
                covar[i+3][j]=new Double(temp[3]);
                covar[i+4][j]=new Double(temp[4]);
                //i=0;
                j++;
            }

            in.close();
        }
        catch(Exception e)

        {
            e.printStackTrace();

        }

以上是代码。文件名是完美的，流的东西没有任何问题。你能帮助我解决这个问题吗？

以下是文件的内容：

0.75,321.0,0.22429906,0.97507787,1.966202512778112
0.33333334,135.0,-0.014814815,1.0,5.323770568766052
0.64285713,311.0,0.025723472,1.0,4.764298570227433
0.6,188.0,0.03723404,1.0,4.7349608150168105
0.25,189.0,0.16931216,0.98941797,7.15681209803803
0.71428573,194.0,-0.26804122,0.96391755,5.1654456838422425
0.6,173.0,0.028901733,1.0,6.54275787030257
0.2857143,257.0,0.031128405,1.0,6.095356508899233
0.23076923,197.0,-0.04568528,1.0,3.784908227189768
0.18181819,231.0,0.17316018,0.987013,5.956322938602553

Answer 1

有两件事显然是错误的：

您不需要变量i，因为其中一个维度是固定的，并且您将循环“展开”了五次
您交换了索引：j应该先行，这是从0更改为9的那个。

例如：

String [] temp=input.split(",");
covar[j][0] = new Double(temp[0]);
covar[j][1] =new Double(temp[1]);
covar[j][2] =new Double(temp[2]);
covar[j][3] =new Double(temp[3]);
covar[j][4] =new Double(temp[4]);

您可以将循环放回来缩短代码：

String [] temp=input.split(",");
for (int i = 0 ; i != 5 ; i++) {
    covar[j][i] = new Double(temp[i]);
}

Answer 2

看起来你正在为矩阵使用错误的索引，我认为它应该是这样的：

int i = 0;
while((input=br.readLine())!= null) {               
    String [] temp=input.split(",");
    //System.out.println(input.split(",").length);
    covar[i][0]= new Double(temp[0]);
    covar[i][1]=new Double(temp[1]);
    covar[i][2]=new Double(temp[2]);
    covar[i][3]=new Double(temp[3]);
    covar[i][4]=new Double(temp[4]);
    ++i;
}

Answer 3

您的文件可能有一些奇怪的行终结符，这使得读者认为有一个额外的行。

您可以尝试让代码跳过空行：

while((input=br.readLine())!= null) {
    if( input.length() > 0 ){
        String [] temp=input.split(",");
        for (int i = 0 ; i != 5 ; i++) {
            covar[j][i] = new Double(temp[i]);
        }
    }
    ++j;
}

来自文件的矩阵

3 个答案: