如何获取二维数组中列的平均值

Question

I have just started using 2D arrays, but can't seem to figure out how to get the average of each column. I am using a for loop to have the user enter the data( a students grade), then a for loop to display the information user entered. But after the information is displayed, I want to display the average of each column. What should I do get the average of each column?

This is the code I have so far

    static void Main(string[] args)
    {
        double[,] grades = new double[2, 3];
        double result;



        for (int i = 0; i < 2; i++)
        {

            for (int j = 0; j < 3; j++)
            {
                Console.Write("Enter Grade " + (j + 1) + " For Group" + (i + 1) + ":   ==>> ");


                if (double.TryParse(Console.ReadLine(), out result)) grades[i, j] = result;
                else
                {
                    Console.WriteLine("*** INVALID GRADE ENTERED. PLEASE REENTER.");

                }
            }

        }





        for (int row = 0; row < 1; row++)
        {
            Console.WriteLine();
            Console.Write("   Group " + (row + 1) + ":        ");
            Console.WriteLine("   Group " + (row + 2) + ":   ");
            Console.Write("===========        ===========");

            for (int col = 0; col < 3; col++)
            {
                //String.Format("{0,-10} | {1,-10} | {2,5}",
                //make pring for execise 2 Console.Write(string.Format("{0,-5}", grades[row, col]));
                Console.WriteLine();
                Console.Write(string.Format("{0,-9}", ""));
                Console.Write(string.Format("{0,-20}",grades[0, col]));
                Console.Write(grades[1,col]);



            }
            Console.WriteLine();
            Console.WriteLine("===========        ===========");


        }



        Console.WriteLine("\n\npress any key to exit...");
        Console.ReadKey();
        //print it for exercise 1 myArr[o, column];  myArr[ , column]
    }` 

Answer 1

If you are looking for a special command that will do it for you, you're out of luck! You'll just have to write the code to do it, the same way you would normally average a series of numbers. Hint: The number of elements in the 'y' dimension of a 2D array is given by eg grades.GetLength(1) .

Answer 2

To get Average per columns you need to traverse columns for a fixed row and add their values like this:

int columnTotal, average;
for (int row = 0; row < 2; row++)
{
    columnTotal = 0;
    for (int col = 0; col < 2; col++)
    {
        columnTotal += grades[row, col];
    }

    average = columnTotal/2;
    Console.WriteLine("Average: {0}", average);
}