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Thread: [Method] How to calculate the sum of a Row or Column in a Multi Dimensional Array

  1. #1
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    Default [Method] How to calculate the sum of a Row or Column in a Multi Dimensional Array

    Hello, I am working on an assignment for my Java class and I just can't figure out the last two methods. I was hoping someone here can point me in the right direction, as searching for an answer online hasn't been helpful.

    I am supposed to build a class that will fill an array and use a GUI to display different function sin the array, such as returning true if the number 7 is included. The last two methods are to return the sum of a column and a row, which column or row is not specified. I am at a loss on how to do this frankly, so hopefully I can get some help.

    //Program Name: StatsArray.java
    //Author: Joshua Rowley
    //Class: CSC110AA
    //Date: 17Oct11
    //Description: This program returns information based on a multiple dimension array.
    // Needs to be able to return sum, average, minimum, maximum, search for a specific number and generate a new array.

    import java.awt.*;
    import java.util.Random; //for our random number generator

    public class MultiStatsArray
    {
    private int rowSize; // how many rows
    private int columnSize; // how many columns
    private int[][] stats; // an array of integers

    MultiStatsArray()
    {
    rowSize = 10;
    columnSize = 5;
    stats = new int[rowSize][columnSize] ; //instantiate the array called stats
    }

    public void display(Graphics g)
    {
    int x = 50; //coordinates for displaying
    int y = 40; // displaying the array
    for(int row = 0; row < stats.length; row++)
    {
    for (int column = 0; column < stats[row].length; column++)
    {
    g.drawString("" + stats[row][column], x + column * 25, (y + 15 * row));
    }
    }
    }

    public void fillArray()
    {
    Random random = new Random();
    for(int row = 0; row < 10; row++)
    {
    for(int column = 0; column < 5; column++)
    {
    stats[row][column] = random.nextInt(100);
    }
    }
    }

    public int getSum() //add up all the values in the array
    {
    int sum = 0;
    Random random = new Random();
    for(int row = 0; row < 10; row++)
    {
    for(int column = 0; column < 5; column++)
    {
    sum += stats[row][column];
    }
    }
    return sum;
    }


    public int getMax() //return the maximum value in the array
    {
    int maximum = stats[9][4];
    for(int row = 0; row < 10; row++)
    {
    for(int column = 0; column < 5; column++)
    {
    if(maximum < stats[row][column])
    {
    maximum = stats[row][column];
    }
    }
    }
    return maximum;
    }

    public int getMin() //return the minimum value in the array
    {
    int minimum = stats[9][4];
    for(int row = 0; row < 10; row++)
    {
    for(int column = 0; column < 5; column++)
    {
    if(minimum > stats[row][column])
    {
    minimum = stats[row][column];
    }
    }
    }
    return minimum;
    }

    public double getAverage()
    {
    return (double) this.getSum() / (rowSize * columnSize);
    }

    public int countValues(int lowRange, int highRange) //count how many numbers are >= lowRange and <= highRange
    {
    int count = 0;
    for(int row = 0; row < 10; row++)
    {
    for(int column = 0; column < 5; column++)
    {
    if((stats[row][column] >= lowRange) && (stats[row][column] <= highRange))
    count++;
    }
    }
    return count;
    }

    public boolean isValueFound(int someNumber)
    {
    for(int row = 0; row < 10; row++)
    {
    for(int column = 0; column < 5; column++)
    {
    if (stats[row][column] == someNumber)
    {
    return true;
    }
    }
    }
    return false;
    }

    public int getRowSum(int row)
    {
    return 0;
    }

    public int getColumnSum(int column)
    {
    return 0;
    }

    }

    ------------------------------------------------------------------------------------------------------------------------------------------

    /* MultiStatsArrayGUI
    This is the GUI tester/controller for the MultiStatsArray class.
    The MultiStatsArray is used to hold 50 grades.

    Patricia Baker
    */

    import java.awt.*;
    import java.awt.event.*;
    import javax.swing.*;

    public class MultiStatsArrayGUI extends JFrame implements ActionListener
    {

    //set up buttons to control the MultiStatsArray
    private JButton maxButton;
    private JButton minButton;
    private JButton sumButton;
    private JButton avgButton;
    private JButton aButton;
    private JButton luckyButton;
    private JButton startOverButton;
    private JButton rangeButton;
    private JButton specificColButton;
    private JButton specificRowButton;

    private JPanel panel;

    /*instantiate your MultiStatsArray object called grades
    creates array of size 10 rows and 5 columns */
    private MultiStatsArray grades = new MultiStatsArray( );

    public static void main(String[] args)
    {
    MultiStatsArrayGUI demo = new MultiStatsArrayGUI();
    demo.setSize(400,400);
    demo.createGUI();
    demo.setVisible(true);
    }

    private void createGUI()
    {
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    Container window = getContentPane();
    window.setLayout(new FlowLayout());

    panel = new JPanel();
    panel.setPreferredSize(new Dimension(300, 200));
    panel.setBackground(Color.white);
    window.add(panel);

    //buttons
    startOverButton = new JButton("New Array");
    window.add(startOverButton);
    startOverButton.addActionListener(this);

    maxButton = new JButton("Maximum");
    window.add(maxButton);
    maxButton.addActionListener(this);

    minButton = new JButton("Minimum");
    window.add(minButton);
    minButton.addActionListener(this);

    sumButton = new JButton("Sum");
    window.add(sumButton);
    sumButton.addActionListener(this);

    avgButton = new JButton("Average");
    window.add(avgButton);
    avgButton.addActionListener(this);

    aButton = new JButton("Number of A's");
    window.add(aButton);
    aButton.addActionListener(this);

    luckyButton = new JButton("Lucky 7");
    window.add(luckyButton);
    luckyButton.addActionListener(this);

    rangeButton = new JButton("Range Test");
    window.add(rangeButton);
    rangeButton.addActionListener(this);

    specificColButton = new JButton("2nd column");
    window.add(specificColButton);
    specificColButton.addActionListener(this);

    specificRowButton = new JButton("3rd row");
    window.add(specificRowButton);
    specificRowButton.addActionListener(this);

    /* invokes method to fill array with random numbers between 1 and 100 */
    grades.fillArray();
    }

    public void actionPerformed(ActionEvent event)
    {
    Graphics g = panel.getGraphics();
    Object source = event.getSource();

    /*cover up old display before drawing the new values. */
    g.setColor(Color.white);
    g.fillRect(0, 0, 300, 200);
    g.setColor(Color.black);

    if (source == minButton)
    g.drawString("Minimum is: " + grades.getMin(), 50, 20);
    if (source == maxButton)
    g.drawString("Maximum is: " + grades.getMax(), 50, 20);
    if (source == sumButton)
    g.drawString("Sum is: " + grades.getSum(), 50, 20);
    if (source == avgButton)
    g.drawString("Average is: " + grades.getAverage(), 50, 20);
    if (source == aButton)
    g.drawString("Number of A's = " + grades.countValues(90, 100), 50, 20);
    if (source == luckyButton)
    g.drawString("Lucky 7 Y or N: " + ( ( grades.isValueFound( 7 ) )? 'Y' : 'N' ), 50, 20);
    if (source == specificColButton)
    g.drawString("The total of the 2nd column is: " + grades.getColumnSum(1), 50, 20);
    if (source == specificRowButton)
    g.drawString("The total of the 3rd row is: " + grades.getRowSum(2), 50, 20);
    if (source == startOverButton)
    {
    grades.fillArray();
    g.drawString("New Values" , 50, 20);
    }
    if (source == rangeButton)
    {
    g.drawString("Number of Values in Range 25 - 50: " + grades.countValues(25,50), 50, 20);
    }
    grades.display(g);
    }

    }


  2. #2
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    Default Re: [Method] How to calculate the sum of a Row or Column in a Multi Dimensional Array

    That is waaay too much code for us to sift through- there are hundreds of posts here, so we don't have a ton of time to wade through hundreds of lines of code. I suggest you create an SSCCE that demonstrates the problem.

    I also recommend you read through this: How to Program (stuck on homework? READ THIS BEFORE POSTING)
    Useful links: How to Ask Questions the Smart Way | Use Code Tags | Java Tutorials
    Static Void Games - Play indie games, learn from game tutorials and source code, upload your own games!

  3. #3
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    Default Re: [Method] How to calculate the sum of a Row or Column in a Multi Dimensional Array

    A good way to work on this you should create a class with just a main method and the method you want to test. Also, highlight your code with:
    [highlight=Java] code [/highlight]

  4. #4

    Default Re: [Method] How to calculate the sum of a Row or Column in a Multi Dimensional Array

    The first thing you should realize is the "direction" that the active element takes in a multidimensional array when traversing through it.

    The 2D array:
    int[][] matrix = new int[3][4];
    Assuming all are initialized to zeros, this creates:

    0 0 0 0
    0 0 0 0
    0 0 0 0

    The array can be accessed via row and column indexing.
    The first index is the row, the second is the column.

    So matrix[1][2] would get you here:
    0 0 0 0
    0 0 0 0
    0 0 0 0

    All arrays start from the upper left corner (0,0):
    0 0 0 0
    0 0 0 0
    0 0 0 0

    and end in the lower right (row.length,column.length) ... (3,4)
    0 0 0 0
    0 0 0 0
    0 0 0 0

    Movement can be achieved by manipulating the indices.
    To go right, increase the column by 1
    To go left, decrease the column by 1
    To go up, decrease the row by 1
    To go down, increase the row by 1

    You can move diagonally by combining this logic.
    Kenneth Walter
    Software Developer
    http://kennywalter.com

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