Bdtjtk

I have an issue with the CSV file: here is a sample of the file.

4.98    24

9.14    21.6

4.03    34.7

2.94    33.4

5.33    36.2

5.21    28.7

12.43   22.9

19.15   27.1

29.93   16.5

17.1    18.9

20.45   15

13.27   18.9

15.71   21.7

8.26    20.4

10.26   18.2

8.47    19.9

6.58    23.1

14.67   17.5

11.69   20.2

11.28   18.2

The aim is to convert it in something like that:

double column1= {4.98, 9.14, 4.03, 2.94, 5.33, 5.21, 12.43, 19.15}; //but with all the values, here it's just a sample

double  column2 = {24, 21.6, 34.7, 33.4, 36.2, 28.7, 22.9, 27.1};

I don't want to write all the data, I need to do a loop but I don't know how I can do it.

I manage to read the csv file and to split the data but not to convert the result into a double array. Here is how I read the file:

String fileName = "dataset.csv";

File file = new File(fileName);

String values;

try{

    Scanner inputStream = new Scanner(file);

    while (inputStream.hasNext()){

        String data = inputStream.next();

        values = data.split(",");

    }

    inputStream.close();



}

catch (FileNotFoundException e){

    e.printStackTrace();

}

Here's a full working example for Java 7:

import java.io.File;

import java.io.IOException;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

import java.util.Scanner;



public class Example

{

    public static void main(String args)

    {

        Scanner inputStream = null;

        try

        {

            String fileName = "dataset.csv";

            File file = new File(fileName);



            // we don't know the amount of data ahead of time so we use lists

            List<Double> col1 = new ArrayList<>();

            List<Double> col2 = new ArrayList<>();



            inputStream = new Scanner(file);

            while (inputStream.hasNext())

            {

                String data = inputStream.next();

                String  arr = data.split(",");



                col1.add(Double.parseDouble(arr[0]));

                col2.add(Double.parseDouble(arr[1]));

            }



            // Covert the lists to double arrays

            double column1 = new double[col1.size()];

            double column2 = new double[col2.size()];



            for (int i = 0; i < col1.size(); i++)

            {

                column1[i] = col1.get(i);

            }



            for (int i = 0; i < col2.size(); i++)

            {

                column2[i] = col2.get(i);

            }



            // print out just for verification

            System.out.println(Arrays.toString(column1));

            System.out.println(Arrays.toString(column2));

        }

        catch (IOException e)

        {

            e.printStackTrace();

        }

        finally

        {

            if (inputStream != null)

            {

                inputStream.close();

            }

        }

    }

}

You can stream the lines from the file and split them to get a String, as you did. You can then stream each such array and convert each item to a double, and then collect them back to arrays:

double data =

    Files.lines(Paths.get(fileName))

         .map(s -> s.split(","))

         .map(s -> Arrays.stream(s).mapToDouble(Double::parseDouble).toArray())

         .toArray(double::new);