t4

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.*;

public class HW01_4 {
    public static void main(String[] args) {
        File f = new File("results.csv");
        File tsv = new File("results.tsv");
        Scanner sc = null;
        PrintWriter pw = null;
        try {
            sc  = new Scanner(f);
            pw = new PrintWriter(tsv);
            if(!sc.hasNext()) {
                System.out.println("The file is empty");
                return;
            }
            Map<Integer, String> subjectByIndex = new HashMap<>();
            Map<String, List<Integer>> subjects = new LinkedHashMap<>();
            Map<String, List<Integer>> students = new LinkedHashMap<>();

            String line = sc.nextLine();
            pw.write(line.replace(",", "\t") + "\n");
            String[] lines = line.split(",");

            for (int i = 1; i < lines.length; i++) {
                subjectByIndex.put(i,lines[i]);
                subjects.put(lines[i],new ArrayList<>());
            }

            while(true) {
                line = sc.nextLine();
                lines = line.split(",");
                String studentIndex = lines[0];
                students.put(studentIndex,new ArrayList<>());

                for (int i = 1; i < lines.length; i++) {
                    int grade = Integer.parseInt(lines[i]);
                    students.get(studentIndex).add(grade);
                    String subject = subjectByIndex.get(i);
                    subjects.get(subject).add(grade);
                }
                if(sc.hasNext())
                    pw.write(line.replace(",", "\t") + "\n");
                else {
                    pw.write(line.replace(",", "\t"));
                    break;
                }
            }
            subjects.keySet().stream()
                    .forEach(key -> {
                        double avg = subjects.get(key)
                                .stream()
                                .mapToInt(i -> i)
                                .average()
                                .getAsDouble();
                        System.out.println("Average grade of " + key + " is " + avg);
                    });
            students.keySet().stream()
                    .forEach(key -> {
                        double avg = students.get(key)
                                .stream()
                                .mapToInt(i -> i)
                                .average()
                                .getAsDouble();
                        System.out.println("Average grade of student with index " + key + " is " + avg);
                    });


        }
        catch (IOException e) {
            e.printStackTrace();
        }
        finally {
            sc.close();
            pw.close();
        }
    }
}