row sum average: Elements appears to be zero when compared

Question

I want to find out row sum average but in case zero appears in the row then that particular column should be left when average of the row is done. let it be more clear. i have a matrix say

5   3   4   4   0
3   1   2   3   3
4   3   4   3   5
3   3   1   5   4
1   5   5   2   1

row sum average for the first row should be 16/4 instead of 16/5 because we left row 1 column 5 since it contains "0" value

i am trying following code. for the first row its working fine but for the rest each row 2-5 and each column 5 its leaving the value although its not zero.

my code is:

    int rows = 5;
    int cols = 5;
    float hostMatrix[] = createExampleMatrix(rows, cols);

    System.out.println("Input matrix:");
    System.out.println(createString2D(hostMatrix, rows, cols));
    float sums[] = new float[rows];
    for(int i=0;i<rows;i++){
        float sum = 0,counter=0;
        for(int j=0;j<cols;j++){
            if(hostMatrix[j]==0){
                sum += hostMatrix[i * cols + j];
            }
            else
    {
                sum += hostMatrix[i * cols + j];
                counter++;
            }
        }
        sum=sum/counter;
    sums[i] = sum;
    }
    System.out.println("sums of the columns ");
    for(int i=0;i<rows;i++){

            System.out.println(" "+sums[i]);

    }

output of the program i receive is:

     sums of the columns 
     4.0
     3.0
     4.75
     4.0
     3.5

i want the output as:

please guide me where i am doing wrong

With each row of your array, you always check for `hostMatrix[j]==0` in the `if`'s condition, and when `j = 4`, of course `hostMatrix[4]==0` in your array. You can try the answer of `nhouser9` below to fix, or simply change `if (hostMatrix[j]==0)` to `if(hostMatrix[i * cols + j]==0)`. — Đăng Khoa Huỳnh, Apr 23 '16 at 12:56

score 0 · Answer 1 · answered Apr 23 '16 at 12:30

0

Your if(hostmatrix[j]==0) check doesn't take into account the row. As a result, every time it arrives at the 5th column, it is at the first row and it sees a zero.

answered Apr 23 '16 at 12:30

Akshay Shenoy

119
8

i tried http://stackoverflow.com/questions/5269183/how-to-compare-integer-with-integer-array but its not working in my case – user3804161 Apr 23 '16 at 12:45

nhouser9 · Accepted Answer · 2016-04-23T12:51:10.073

The code below should fix this. The problem was that your inner loop was not iterating correctly. I changed it to index into the right spot in the array. Let me know if it works!

int rows = 5;
int cols = 5;
float hostMatrix[] = createExampleMatrix(rows, cols);

System.out.println("Input matrix:");
System.out.println(createString2D(hostMatrix, rows, cols));
float sums[] = new float[rows];
for(int i=0; i<rows; i++){
    float sum = 0,counter=0;
    for(int j=0; j<cols; j++){

        //the problem was here
        if(hostMatrix[i * cols + j] != 0){
            sum += hostMatrix[i * cols + j];
            counter++;
        }
    }
    sum=sum/counter;
    sums[i] = sum;
}

System.out.println("sums of the columns ");
for(int i=0;i<rows;i++){
        System.out.println(" "+sums[i]);
}

score 0 · Answer 3 · answered Apr 23 '16 at 12:37

0

Edit the following line:

if(hostMatrix[j]==0)

It should be:

if(hostMatrix[i][j]==0)

So that it does not remain on the first row and always find a 0.

answered Apr 23 '16 at 12:37

Andrei-Marius Longhin

563
3
7

He's using a one-demension array. Fix the `if` condition: `if (hostMatrix[i * cols + j] == 0)` – Đăng Khoa Huỳnh Apr 23 '16 at 12:49

row sum average: Elements appears to be zero when compared

3 Answers3