我需要关于 JAVA 中二维数组平均评分的代码的帮助

Question

I need help with my code which that my input ratings is

-1 2 3 5 -1 5 3 3 1 4 2 2 5 -1 1 3 3 5 4 3
-1 1 1 4 1 3 3 1 2 3 4 -1 4 1 2 4 5 4 2 3
3 -1 2 3 -1 2 5 -1 3 3 5 2 2 1 2 3 5 3 4 2
-1 1 -1 4 1 3 5 2 1 5 3 -1 5 2 1 3 4 5 3 2
-1 -1 3 2 -1 5 5 2 2 4 4 2 3 2 -1 3 4 4 3 1
2 1 1 5 2 2 4 2 3 4 3 -1 5 2 2 5 3 5 2 1
3 -1 3 4 -1 2 5 -1 -1 4 3 -1 3 -1 2 5 5 5 4 2
4 -1 4 2 3 -1 1 3 4 -1 1 4 4 4 -1 2 -1 1 4 4
4 3 3 3 -1 2 2 4 3 -1 2 4 3 4 2 -1 -1 2 2 3
3 -1 3 -1 3 4 -1 5 5 -1 -1 -1 1 -1 -1 1 1 2 -1 5
3 -1 3 4 3 4 -1 5 5 2 3 3 4 1 1 -1 -1 -1 -1 4
4 -1 4 4 1 3 -1 5 4 -1 1 3 4 1 -1 1 -1 1 -1 5
5 -1 3 1 4 3 -1 5 4 1 3 2 1 -1 4 2 1 -1 2 4
3 -1 5 1 4 4 2 5 5 1 2 3 1 1 -1 1 -1 1 -1 5
4 1 5 4 3 -1 1 3 4 -1 -1 3 3 -1 1 1 2 -1 3 5
-1 1 1 3 -1 3 1 3 -1 -1 3 -1 5 2 2 1 4 -1 5 -1
3 -1 2 3 1 5 4 3 3 -1 5 -1 5 2 -1 4 4 3 3 3
1 1 1 3 2 4 1 -1 -1 -1 5 -1 3 -1 -1 1 -1 2 5 2
-1 2 3 5 -1 4 3 1 1 3 3 -1 4 -1 -1 4 3 2 5 1
-1 1 3 3 -1 3 3 1 -1 -1 3 -1 5 -1 -1 3 1 2 4 -1
3 -1 2 4 1 4 3 -1 2 3 4 1 3 -1 2 -1 4 3 5 -1
-1 1 3 5 -1 4 2 1 -1 3 3 2 3 2 -1 3 1 -1 3 -1
3 2 2 3 -1 5 -1 -1 2 3 4 -1 4 1 -1 -1 -1 -1 4 2
-1 3 -1 -1 4 -1 2 -1 2 2 2 5 -1 3 4 -1 -1 2 -1 2
1 4 3 -1 3 2 1 -1 -1 -1 1 3 1 3 3 1 -1 -1 -1 3
4 3 3 -1 4 2 -1 4 -1 -1 2 4 -1 3 4 2 -1 -1 -1 4
-1 5 1 -1 4 1 -1 3 2 2 -1 4 1 3 3 1 -1 -1 -1 3
-1 4 2 1 5 -1 -1 2 1 1 -1 5 -1 5 4 1 2 2 -1 1
2 5 2 -1 3 -1 -1 1 -1 2 -1 4 2 4 3 -1 2 1 -1 -1
2 5 1 1 4 -1 2 1 -1 -1 2 4 -1 3 4 2 -1 -1 -1 4

which I am taking the first role of the rate by vertically which my average[] has 20 values. I am confused about where is wrong with my code such that if number = -1, then it set to 0 and then doesn't count. This is a code to count the average rating of a book, my average[] value comes out different then my calculation on a calculator.

public static double [] recommandratings(double[][]ratings) {
    double [] average = new double[20];
    int [] count = new int[20];
    double[] sum = new double[30];
    Arrays.fill(count,0);
    Arrays.fill(sum, 0);
    for(int i= 0;i<20;i++) {
        for(int j=0; j<30; j++) {
            if(ratings[j][i] == -1) {
                ratings[j][i] = 0;
                sum[i] += ratings[j][i];
                count[i]--;
            } else {
                sum[i] += ratings[j][i];
                count[i]++;
            }
        }
    }
    for(int a =0; a<20;a++) {
        average[a] = sum[a]/count[a];
    }
    return average;
}

Answer 1

Since you don't want to count number with value -1, there is no use of count[i]-- because you are increasing count only when there is a number not equal to -1.

Answer 2

I think the way of iteration of the 2D array is wrong in your case. I made the following changes to make it simple and dynamic. I hope the following code will give you desired result.

public static double [] recommandratings (double[][]ratings) {
        int rowSize = ratings.length;
        int colSize = ratings[0].length;
        double [] average = new double[colSize];
        int[] count = new int[colSize];
        for (int row= 0;row < rowSize;row++) {
            for (int col=0; col < colSize; col++) {
                if (ratings[row][col] != -1) {
                    average[col] += ratings[row][col];
                    count[col]++;
                }
            }
        }
        for (int a =0; a < colSize;a++) {
            int sum = (int) average[a];
            average[a] = average[a] / count[a];
            System.out.println("count[" + a + "]=" + count[a] + "; sum[" + a + "]=" + sum + "; average[" + a + "]=" + average[a]);
        }
        return average;
}

PS I removed the sum[] and reused the average[] to optimize memory.

Update

This update is based on the comments where you state that the count[a] is always returning 30, where it should be less than 30. I performed a test with both your exact dataset and a smaller dataset. I found my solution is returning less than 30 which is expected. Therefore, I think you made some mistake in integrating my solution. So, I have made a gist with complete source code and input/output as well which will help you integrate it correctly.