Read file and change the values

[Rebekah]

Hi,

I'm really stuggling with a program i'm trying to create
I have to normalise some data so the the values are in the range [0,1]. I want to do this by taking the greates value in each column and dividing every other value by this.
Example: i have a txt file -
6, 148, 72, 35, 0, 336, 0627, 50, 2
1, 85, 66, 29, 0, 266, 0351, 31, 1
8, 183, 64, 0, 0, 233, 0672, 32, 2
1, 89, 66, 23, 94, 281, 0167, 21, 1
0, 137, 40, 35, 168, 431, 2288, 33, 2
5, 116, 74, 0, 0, 256, 0201, 30, 1

if i take the first column, i would want to divide each value by 8.
I've wrote a program that reads the file and puts each line into an array, but want i want is each column in an array/vector(whichever is best) and i really don't know how to do this.

My code so far:

import java.io.*;
import java.util.*;

public class FileIO
{
public static void main(String[] args)
{
ArrayList bob = loadFile("testfile.txt");
for (int i=0; i<bob.size(); i++)
System.out.println(i+1 + ":\t" + bob.get(i));
}
public static ArrayList loadFile(String fileName)
{
ArrayList file = new ArrayList();
try
{
BufferedReader in = new BufferedReader(new FileReader(fileName));
if (!in.ready()) throw new IOException();
while ((line = in.readLine()) != null)
file.add(line);
in.close();
}
catch (IOException e)
{
System.out.println(e);
return null;
}
return file;
}
}

i'd want to put each column in an array then perform the calculations on each column.
Can anyone please help me?

[sjalle]

I have hacked up two solutions here, one with ArrayList and one with a
matrix, but... I haven't tested it

import java.io.*;
import java.util.*;
import java.text.*;

public class FileIO {

  public static DecimalFormat dF=new DecimalFormat("0.00");

  public FileIO() {}

  public void doArrayListSolution ()  throws Exception {
    ArrayList bob = loadFileAL("testfile.txt");
    for (int i = 0; i < bob.size(); i++) {
      System.out.println(i + 1 + ":\t" + bob.get(i));
    }
  }
  public void doMatrixSolution () throws Exception {
    double [][] fileMX = loadFileMX("testfile.txt");
    for (int i = 0; i < fileMX.length; i++) {
      for (int j=0; j<fileMX[i].length; j++) {
        System.out.print(dF.format(fileMX[i][j]+"\t"));
      }
      System.out.println();
    }
  }
  private int countRecords(String fileName)throws IOException {
    String line=null;
    int count=0;
    BufferedReader in = new BufferedReader(new FileReader(fileName));
    while ( (line = in.readLine()) != null) count++;
    in.close();
    return count;
  }
  /**
  * MAtrix
  * @param fileName
  * @return double matrix
  */
 public double [][] loadFileMX(String fileName) throws Exception {
   String line = null;
   double [][] data=new double[countRecords(fileName)][];
   BufferedReader in = new BufferedReader(new FileReader(fileName));
   int lineNo=0;
   while ( (line = in.readLine()) != null) {
     /**
      * Split line into array of strings, create double array,
      * Store row of parsed doubles in the matrix.
      */
     String[] ss = line.split(",");
     double[] dd = new double[ss.length];
     for (int i = 0; i < ss.length; i++) {
       dd[i] = Integer.parseInt(ss[i]);
     }
     data[lineNo++]=dd;
   }
   in.close();
   return data;
 }

  /**
   * Arraylist
   * @param fileName
   * @return arrayList of double arrays
   */
  public ArrayList loadFileAL(String fileName) throws Exception {
    String line = null;
    ArrayList file = new ArrayList();

    BufferedReader in = new BufferedReader(new FileReader(fileName));
    while ( (line = in.readLine()) != null) {
      /**
       * Split line into array of strings, create double array,
       * Store parsed doubles in the array.
       */
      String[] ss = line.split(",");
      double[] dd = new double[ss.length];
      for (int i = 0; i < ss.length; i++) {
        dd[i] = Integer.parseInt(ss[i]);
      }
      /**
       * stuff the double array into the arrayList.
       * Rerieve like: double [] lineVals=(double[])list.get(i);
       */
      file.add(dd);
    }

    in.close();
    return file;
  }

  public static void main(String[] args) {
    FileIO fio = new FileIO();
    try {
      fio.doArrayListSolution();
      fio.doMatrixSolution();
    }
    catch (Exception ex) {
      System.err.println("This didn't go so well...");
      ex.printStackTrace();
    }
  }

}