Question

我需要编写一个方法，将矩阵（对象）旋转90度，两个方向。

例如 -

( 0,0,0) (0,0,0) (0,0,0) (0,0,0)

( 1,1,1) (1,1,1) (1,1,1) (1,1,1)

( 2,2,2) (2,2,2) (2,2,2) (2,2,2)

成为 -

(2,2,2) (1,1,1) (0,0,0)

(2,2,2) (1,1,1) (0,0,0)

(2,2,2) (1,1,1) (0,0,0)

(2,2,2) (1,1,1) (0,0,0)

我无法克服“ArrayIndexOutOfBoundsException”错误。

这是我目前的工作 -

private RGBColor [][] _picture;
private int _row;
private int _col;

public RGBImage(RGBColor[][] pixels)
{
    _picture = new RGBColor [pixels.length][pixels[0].length];
    _row = pixels.length;
    _col = pixels[0].length;

    for(int i = 0 ; i < pixels.length ; i++)
    {
        for(int j = 0 ; j < pixels[0].length ; j++)
        {
            _picture[i][j] = pixels[i][j];
        }
    }
}

public double[][] toGrayscaleArray ( )
{
    double [][] copyToGrayscale = new double [_row][_col];
    for(int i = 0 ; i < _row ; i++)
        {
            for(int j = 0 ; j < _col ; j++)
            {
               copyToGrayscale [i][j] = _picture[i][j].convertToGrayscale();
            }
        }
        return copyToGrayscale;
}

public void rotateCounterClockwise ( )
{
    RGBImage copy = new RGBImage(_col,_row);
    for(int i=0 ; i < _col ; i++)
    {
        for(int j=_row-1 ; j >0 ; j--)
        {
            copy._picture[i][j]=_picture[j][i];
        }
    } 
    _picture = copy.toRGBColorArray();     
}

我该怎么办？感谢。

Answer 1

尝试：

for(int i = amount_columns-1; i>=0; i--) {
    for(int j = amount_rows-1; j>=0; j--) {

         new image[(amount_cols-1)-j][(amount_rows-1)-i] = old image[j][i];
    }

}

这段代码应该执行以下操作：

amount_colums = 4
amount_row = 3
new image[(amount_cols-1)-j][(amount_rows-1)-i] = old image[j][i]

i=3;j=2 --> new image[4-1-3 = 0][3-1-2 = 0] = old image [2][3];
i=3;j=1 --> new image[4-1-3 = 0][3-1-1 = 1] = old image [1][3];
i=3;j=0 --> new image[4-1-3 = 0][3-1-0 = 2] = old image [0][3];
i=2;j=2 --> new image[4-1-2 = 1][3-1-2 = 0] = old image [2][2];
i=2;j=1 --> new image[4-1-2 = 1][3-1-1 = 1] = old image [1][2];
i=2;j=0 --> new image[4-1-2 = 1][3-1-0 = 2] = old image [0][2];
i=1;j=2 --> new image[4-1-1 = 2][3-1-2 = 0] = old image [2][1];
... and so on.

如果它不起作用，我现在无法测试。

Answer 2

我认为这会奏效：

    int[][] arr = new int[][]{
        {0,0,0},
        {1,1,1},
        {2,2,2},
        {3,3,3},
        {4,4,4},
    };

    int[][] rotated = new int[arr[0].length][arr.length];
    for (int row = arr.length -1; row >= 0; row--){
        int destCol = arr.length -1 - row;
        int destRow = 0;
        for(int col = 0; col < arr[0].length; col++){
            rotated[destRow++][destCol] = arr[row][col];
        }
    }

    for(int row = 0; row < rotated.length; row++){
        for(int col = 0; col < rotated[0].length; col++) {
            System.out.print(rotated[row][col] + ",");
        }
        System.out.println();
    }

根据您的需要，更好地使用jai API。或者也许从java Graphic2D类转换为affini。

Answer 3

import java.util.Scanner;

class Rotate90
{

    public static void main(String [] args)
    {
        Scanner sc=new Scanner(System.in);
        System.out.println("enter the row ");
        byte row=sc.nextByte();
        System.out.println("enter the column");
        byte column=sc.nextByte();
        int arr[][]=new int[row][column];
        // enterMatrixData(scan, matrix, matrixRow, matrixCol);
        System.out.println("row entered is: "+row+",\ncolumn entered is: "+column);
        System.out.println("now enter the maitix data");
        for(int j=0;j<arr.length;j++)
                 {
                    for(int i=0;i<arr.length;i++)
                    {
                    arr[j][i]=sc.nextInt();

                    }

                 }

                 for(int j=0;j<arr.length;j++)
                 {
                    for(int i=0;i<arr.length;i++)
                    {

                    System.out.print(arr[j][i]+"\t");
                    }
                    System.out.println("");
                 }

        System.out.println("");
        System.out.println("After 90* rotation");

        for(int j=0;j<arr.length;j++)   // logic for clock-wise 90* rotation 
                 {
                    for(int i=arr.length-1;i>=0;i--)
                    {
                     System.out.print(arr[i][j]+"\t");
                    }
                    System.out.println("");
                 }
    }
}

用Java旋转矩阵90度

3 个答案: