CODEWITHSUNDEEP
javaarraysmultidimensional-array
AngryDuck
AngryDuck

Reputation: 4607

flipping a multi-dimensional array java

i have a class that creates a canvas of characters with a desired width and height.

within this i have a method drawLetter() (which basically changes the characters so that a letter appears on the canvas (like very simple ASCII art)

i have 3 other methods rotateClockwise, flipHorizontal, and flipVertical

rotate and flipHorizontal i have done fine and they work but i cannot seem to work out where im going wrong with flipping the array vertically (out of interest i think i have horizontal and vertical the wrong way round but ill put a sample of what im trying to get done below)

this is what i cant work out:

this:

# # # ~
~ # ~ ~
~ # ~ ~
~ ~ ~ ~

to this:

~ # # #
~ ~ # ~
~ ~ # ~
~ ~ ~ ~

obviously it will be done in a for loop like my other methods, below i will post the method i have done already for horizontal and rotate clockwise to prove its not homework i cant do

void mirrorHorizontally()
{
    char[][]horizontalImage = new char[height][width];

    for (int i = 0; i < height /2; i++)
    { 
       for(int j = 0; j < width; j++)
       {  
           horizontalImage[height - (i+1)][j] = canvasArray[i][j];           
           horizontalImage[i][j] = canvasArray[height - (i+1)][j];
       }
    }   
    printPicture(horizontalImage);
}


void rotateClockwise()
{
    char[][] rotatedImage = new char[height][width];

    for(int i=0; i< canvasArray.length; i++)
    {
        for(int j= canvasArray.length-1; j >= 0; j--)
        {
            rotatedImage[i][rotatedImage.length-1-j] = canvasArray[j][i]; 
        }
    }

    printPicture(rotatedImage);
}

canvasArray is the original image out of interest in a char[][] class variable

Upvotes: 3

Views: 10528

Answers (1)

sp00m
sp00m

Reputation: 48837

This should suit your needs:

public static char[][] mirror(int width, int height, char[][] in) {
    char[][] out = new char[height][width];
    for (int i = 0; i < height; i++) {
        for (int j = 0; j < width; j++) {
            out[i][width - j - 1] = in[i][j];
        }
    }
    return out;
}

For example:

char[][] in = new char[][] {
    new char[] { '#', '#', '#', '~' },
    new char[] { '~', '#', '~', '~' },
    new char[] { '~', '#', '~', '~' },
    new char[] { '~', '~', '~', '~' },
    new char[] { '~', '~', '~', '~' }
};

for (char[] line : mirror(4, 5, in)) {
    for (char row : line) {
        System.out.print(row);
    }
    System.out.println();
}

Prints:

~###
~~#~
~~#~
~~~~
~~~~

Upvotes: 3

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