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Java implement cross correlation 2d image

enter image description here
Can i implement the cross-correlation in the same way as the convolution?
I want to implement the formula in as in the picture, where Li the kernel in 4 different direction filters; Ci is the magnitude map for direction i. So what I did is to find the cross-correlation in the four directions separately and add them up. I learned that the cross correlation can be the same as convolution in image line sharping; s as the result should be stroke line of an image but what I actually get are discrete points. I am not sure if I implemented the formula correctly. Please help
private static void sharpTheLine(){
int[][] cC_0= crossCorrelation(KERNEL_0,CMap_0);
int[][] cC_45=crossCorrelation(KERNEL_45,CMap_45);
int[][] cC_90=crossCorrelation(KERNEL_90,CMap_90);
int[][] cC_135=crossCorrelation(KERNEL_135,CMap_135);
//generate S
for(int i=0; i<imageWidth; i++){
for(int j =0; j<imageHight; j++) {
SMap[i][j] = cC_0[i][j]+cC_45[i][j]+cC_90[i][j]+cC_135[i][j];
}
}
}
private static int[][] crossCorrelation(int [][] kernel,int[][] CMapVal){
int horizontalWalk = imageWidth - K_R;
int verticalWalk = imageHight - K_C;
int res[][]=new int[imageWidth][imageHight];
for (int i = 0; i < horizontalWalk; i++) {
for (int j = 0; j < verticalWalk; j++) {
int sample[][] = new int[K_R][K_C];
for (int k = i; k < K_R + i; k++) {
for (int m = j; m < K_C + j; m++) {
sample[k - i][m - j] = CMapVal[k][m];
OnePixelConvolution(sample, i, j, kernel, res);
}
}
}
}
return res;
}
private static void OnePixelConvolution(int[][] sample, int x, int y, int [][]kernel, int [][] res) {
int resrgb = 0;
for (int i = 0; i < K_R; i++) {
for (int j = 0; j < K_C; j++) {
resrgb = resrgb + sample[i][j] * kernel[i][j];
}
}
res[x][y] = resrgb;
}

How can I check if every single int in a randomly generated array is even and make it create another random array if it's not?

So I'm trying to create a program that creates a randomly generated array with numbers between 0 and 10.
Every time a number inside the 4x4 array is odd I want it to generate a brand new array and print every array discarded aswell until it creates a 4x4 array with only even numbers.
The problem right now is that I can't understand how to fix the last for and make it work properly with the boolean b that is supposed to restart the creation of the array.
import java.util.Scanner;
public class EvenArrayGenerator {
public static void main(String a[]) {
Boolean b;
do {
b = true;
int[][] Array = new int[4][4];
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++)
Array[i][j] = (int) (Math.random() * 11);
}
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
System.out.print(Array[i][j] + " ");
}
System.out.println();
}
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
if (Array[i][j] % 2 != 0)
b = false;
}
}
} while (b);
}
}

public class ArrayGen {
private int[][] array = new int[4][4];
private int iterations = 1; // you always start with one iteration
public static void main (String[] args) {
ArrayGen ag = new ArrayGen();
ag.reScramble();
while(!ag.isAllEven()) {
ag.reScramble();
ag.iterations++;
}
// this is just a nice visualisation
for (int i = 0; i < 4; i++) {
System.out.print("[");
for (int j = 0; j < 4; j++) {
System.out.print(ag.array[i][j] +((j != 3)? ", " : ""));
}
System.out.print("]\n");
}
System.out.println(ag.iterations + " iterations needed to get all-even array.");
}
private void reScramble () {
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
array[i][j] = (int)(Math.random() * 11);
}
}
}
private boolean isAllEven () {
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
if (array[i][j] % 2 == 1) {
return false;
}
}
}
return true;
}
}
I think this is a good solution. Refactoring your code into structured methods is never a bad idea. I hope this helps!

You are looping until you get an array that's all even. You should initialize b to be false, and update it to true in the (nested) for loop. Note that once's you've set it to false, there's no reason checking the other members of the array, and you can break out of the for loop.
Note, also, that using stream could make this check a tad more elegant:
b = Arrays.stream(arr).flatMapToInt(Arrays::stream).anyMatch(x -> x % 2 != 0)

What about generating random numbers up to 5 and double it? Then you don't have two check if they are even.

Instead of your last for loop:
for(int i=0;i<4;i++){
for(int j=0;j<4;j++){
if(Array[i][j] % 2!=0){
b=false;
break;
}
}
if(!b){
break;
}
}
if(!b){
break;
}
Alternatively, you could do an oddity check when you are generating the elements. Something like:
int element;
for(int i=0;i<4;i++){
for(int j=0;j<4;j++){
do{
element = (int)(Math.random()*11);
}while(element % 2 !=0)
Array[i][j] = element;
}
}
That way you don't have to check the values, they will always be even.

This should work:
import java.util.Scanner;
public class EvenArrayGenerator{
public static void main(String a[]){
boolean anyOdd;
int array = 0;
do{
System.out.println ("Array " + ++array + ":");
anyOdd=false;
int[][] Array = new int[4][4];
for(int i=0;i<4;i++) {
for(int j=0;j<4;j++) {
Array[i][j] = (int)(Math.random()*11);
}
}
for(int i=0;i<4;i++){
for(int j=0;j<4;j++){
System.out.print(Array[i][j] + " ");
}
System.out.println();
}
for(int i=0;i<4;i++){
for(int j=0;j<4;j++){
anyOdd |= Array[i][j] % 2!=0;
}
}
} while(anyOdd);
}
}
As you can see, I just modified the condition from b to anyOdd, so if there is any odd number, it will iterate again.
Also, you can check it when you generate the random numbers, so you avoid a second loop:
import java.util.Scanner;
public class EvenArrayGenerator{
public static void main(String a[]){
boolean anyOdd;
int array = 0;
do{
System.out.println ("Array " + ++array + ":");
anyOdd=false;
int[][] Array = new int[4][4];
for(int i=0;i<4;i++) {
for(int j=0;j<4;j++) {
Array[i][j] = (int)(Math.random()*11);
anyOdd |= array[i][j] % 2 != 0;
}
}
for(int i=0;i<4;i++){
for(int j=0;j<4;j++){
System.out.print(Array[i][j] + " ");
}
System.out.println();
}
} while(anyOdd);
}
}

public class EvenArrayGenerator {
public static void main(String a[]) {
int[][] arr = createAllEvenArray(4);
printArray(arr);
}
private static int[][] createAllEvenArray(int size) {
while (true) {
int[][] arr = createArray(size);
printArray(arr);
if (isAllEven(arr))
return arr;
}
}
private static int[][] createArray(int size) {
int[][] arr = new int[size][size];
for (int i = 0; i < arr.length; i++)
for (int j = 0; j < arr.length; j++)
arr[i][j] = (int)(Math.random() * 11);
return arr;
}
private static void printArray(int[][] arr) {
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
if (j > 0)
System.out.print("\t");
System.out.format("%2d", arr[i][j]);
}
System.out.println();
}
System.out.println();
}
private static boolean isAllEven(int[][] arr) {
for (int i = 0; i < arr.length; i++)
for (int j = 0; j < arr.length; j++)
if (arr[i][j] % 2 != 0)
return false;
return true;
}
}

ArrayIndexOutOfBoundsException when trying to find the determinant of a 2D Array/Matrix

this is my first Stack Overflow post, and I am fairly new to java, so I may not initially comprehend some of the feedback you give me.
With this program, I am supposed to find the determinant of a matrix recursively with a size determined by the user. When I do so, however, I get this error:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 1
at Determinant.Copy<Determinant.java:55>
at Determinant.det<Determinant.java:31>
at Determinant.main<Determinant.java:15>
I understand what this error means, but I don't understand why it's happening.
Here are the classes I am using (both printmatrix and the main method were written by my teacher, I had to complete the Copy and det methods):
import javax.swing.JOptionPane;
public class Determinant
{
public static void main(String args[])
{
String sizeStr = JOptionPane.showInputDialog("What size?");
int size = Integer.parseInt(sizeStr);
int[][] matrix = new int[size][size];
for(int i=0; i<size; i++)
for(int j=0; j<size; j++)
matrix[i][j] = (int)(Math.random()*40)-20;
printArray(matrix);
System.out.println("\nThe determinant = "+det(matrix));
}
public static int det(int[][] A)
{
int answer = 0;
int place = 0;
int[][] temp;
int[][] temp1;
if(A.length==1){
return(A[0][0]);
}
for(int i = 0; i<A.length; i++){
temp = new int[A.length-1][A[0].length-1];
temp1 = Copy(temp, i);
if(i%2==0){
place = 1;
}
else{
place = -1;
}
answer = answer + place * A[0][i] * det(temp1);
}
return answer;
}
public static int[][] Copy(int[][] B, int i)
{
int[][] C = new int[B.length-1][B.length-1];
for(int j = 1; j<B.length; j++){
for(int k = 0; k<B[0].length; k++){
if(k>i){
C[j-1][k-1]=B[j][k];
}
else{
C[j-1][k]=B[j][k];
}
}
}
return C;
}
public static void printArray(int[][] A)
{
for(int i=0; i<A.length; i++)
{
for(int j=0; j<A.length; j++)
{
int num = A[i][j];
if(num<-9)
System.out.print(" ");
else if(num<0||num>9)
System.out.print(" ");
else
System.out.print(" ");
System.out.print(A[i][j]);
}
System.out.println();
}
}
}
The error occurs at the else statement in Copy and temp1 = Copy(temp, i).
I am confused, as if either j or k = 1, shouldn't that be a position in the array? What am I missing?

The size of C array in method copy, should be same as B array.
Reason: You are copying B array into C array, they should have same size.
Try the following:
import javax.swing.JOptionPane;
public class Determinant
{
public static void main(String args[])
{
String sizeStr = JOptionPane.showInputDialog("What size?");
int size = Integer.parseInt(sizeStr);
int[][] matrix = new int[size][size];
for(int i=0; i<size; i++) {
for(int j=0; j<size; j++) {
matrix[i][j] = (int) (Math.random() * 40) - 20;
}
}
printArray(matrix);
System.out.println("\nThe determinant = "+det(matrix));
}
public static int det(int[][] A)
{
int answer = 0;
int place = 0;
int[][] temp;
int[][] temp1;
if(A.length==1){
return(A[0][0]);
}
for(int i = 0; i<A.length; i++){
temp = new int[A.length-1][A[0].length-1];
temp1 = Copy(temp, i);
if(i%2==0){
place = 1;
}
else{
place = -1;
}
answer = answer + place * A[0][i] * det(temp1);
}
return answer;
}
public static int[][] Copy(int[][] B, int i)
{
//The C array size should be same as B
int[][] C = new int[B.length][B[0].length];
for(int j = 1; j<B.length; j++){
for(int k = 0; k<B[0].length; k++){
if(k>i){
C[j-1][k-1]=B[j][k];
}
else{
C[j-1][k]=B[j][k];
}
}
}
return C;
}
public static void printArray(int[][] A)
{
for(int i=0; i<A.length; i++)
{
for(int j=0; j<A.length; j++)
{
int num = A[i][j];
if(num<-9)
System.out.print(" ");
else if(num<0||num>9)
System.out.print(" ");
else
System.out.print(" ");
System.out.print(A[i][j]);
}
System.out.println();
}
}
}
Hope this explains, enjoy!

You should declare your matrix in Copy function in this way:
int[][] C = new int[B.length][B[0].length];
Otherwise you are declaring a matrix without a row and column. The fact that you start to use from 0 doesn't mean you should declare one row in less!

Scaling output with for loop

What I'm trying to do is make a box, like so:
|../\..../\..|
|./\/\../\/\.|
|/\/\/\/\/\/\|
|\/\/\/\/\/\/|
|.\/\/..\/\/.|
|..\/....\/..|
and the code for it is
public static void drawUpper(int count)
{
System.out.print("|");
for(int i = 0; i <= (count); i++){
System.out.print(".");
}
for(int i = 0; i <= (-count + 1); i++){
System.out.print("/\\");
}
for(int i = 0; i <= count; i++){
System.out.print(".");
}
for(int i = 0; i <= count; i++){
System.out.print(".");
}
for(int i = 0; i <= (-count + 1); i++){
System.out.print("/\\");
}
for(int i = 0; i <= count; i++){
System.out.print(".");
}
System.out.print("|");
System.out.println();
}
public static void drawLower(int count)
{
System.out.print("|");
for(int i = 0; i <= -count; i++){
System.out.print(".");
}
for(int i = 0; i <= (count + 1); i++){
System.out.print("\\/");
}
for(int i = 0; i <= -count; i++){
System.out.print(".");
}
for(int i = 0; i <= -count; i++){
System.out.print(".");
}
for(int i = 0; i <= (count + 1); i++){
System.out.print("\\/");
}
for(int i = 0; i <= -count; i++){
System.out.print(".");
}
System.out.print("|");
System.out.println();
}
However, this needs to be at a scale, its current scale, is 5;
private static int size = 5;
public static void main(String[] args)
{
for(int i = 1; i > (-size / 2); i--){
drawUpper(i);
}
for(int i = 1; i > (-size / 2); i--){
drawLower(i);
}
}
Now, so long as the scale doesn't change it works perfectly, and I'm quite pleased with myself. However when i change the scale to 7 the box seems to turn into this:
|../\..../\..|
|./\/\../\/\.|
|/\/\/\/\/\/\|
|/\/\/\/\/\/\/\/\|
|\/\/\/\/\/\/|
|.\/\/..\/\/.|
|..\/....\/..|
|............|
However, it's supposed to look like this:
|....../\............/\......|
|...../\/\........../\/\.....|
|..../\/\/\......../\/\/\....|
|.../\/\/\/\....../\/\/\/\...|
|../\/\/\/\/\..../\/\/\/\/\..|
|./\/\/\/\/\/\../\/\/\/\/\/\.|
|/\/\/\/\/\/\/\/\/\/\/\/\/\/\|
|\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
|.\/\/\/\/\/\/..\/\/\/\/\/\/.|
|..\/\/\/\/\/....\/\/\/\/\/..|
|...\/\/\/\/......\/\/\/\/...|
|....\/\/\/........\/\/\/....|
|.....\/\/..........\/\/.....|
|......\/............\/......|

Here's what I came up with. I only provided code for producing one diamond (I won't do all the work for you ;)). It's trivial to adapt it to produce two diamonds, so it's up to you to make those changes (it's really not difficult at all, given the code below).
// aliases for java's verbose methods
public static void p(char c) { System.out.print(c); }
public static void pn(char c) { System.out.println(c); }
// convenient shortcut for alternating between characters
public static char[] a = {'/', '\\'};
public static void dotop(int size, int line) {
p('|');
for (int i=0; i<size-line; i++) p('.');
for (int i=0; i<line+1; i++) p(a[i%2]);
for (int i=0; i<line+1; i++) p(a[(i+1+line)%2]);
for (int i=0; i<size-line; i++) p('.');
pn('|');
}
public static void dobottom(int size, int line) {
p('|');
for (int i=0; i<size-line; i++) p('.');
for (int i=0; i<line+1; i++) p(a[(i+line+(line+1)%2)%2]);
for (int i=0; i<line+1; i++) p(a[(i+1+(line+1)%2)%2]);
for (int i=0; i<size-line; i++) p('.');
pn('|');
}
public static void main(String[] args) {
int size = 4;
for (int i=0; i<=size; i++) dotop(size, i);
for (int i=0; i<=size; i++) dobottom(size, size-i);
}
The produced output is:
|..../\....|
|.../\/\...|
|../\/\/\..|
|./\/\/\/\.|
|/\/\/\/\/\|
|\/\/\/\/\/|
|.\/\/\/\/.|
|..\/\/\/..|
|...\/\/...|
|....\/....|

How to print a two dimensional array?

I have a [20][20] two dimensional array that I've manipulated. In a few words I am doing a turtle project with user inputting instructions like pen up = 0 and pen down = 1. When the pen is down the individual array location, for instance [3][4] is marked with a "1".
The last step of my program is to print out the 20/20 array. I can't figure out how to print it and I need to replace the "1" with an "X". The print command is actually a method inside a class that a parent program will call. I know I have to use a loop.
public void printGrid() {
System.out.println...
}

you can use the Utility mettod. Arrays.deeptoString();
public static void main(String[] args) {
int twoD[][] = new int[4][];
twoD[0] = new int[1];
twoD[1] = new int[2];
twoD[2] = new int[3];
twoD[3] = new int[4];
System.out.println(Arrays.deepToString(twoD));
}

public void printGrid()
{
for(int i = 0; i < 20; i++)
{
for(int j = 0; j < 20; j++)
{
System.out.printf("%5d ", a[i][j]);
}
System.out.println();
}
}
And to replace
public void replaceGrid()
{
for (int i = 0; i < 20; i++)
{
for (int j = 0; j < 20; j++)
{
if (a[i][j] == 1)
a[i][j] = x;
}
}
}
And you can do this all in one go:
public void printAndReplaceGrid()
{
for(int i = 0; i < 20; i++)
{
for(int j = 0; j < 20; j++)
{
if (a[i][j] == 1)
a[i][j] = x;
System.out.printf("%5d ", a[i][j]);
}
System.out.println();
}
}

Something like this that i answer in another question
public class Snippet {
public static void main(String[] args) {
int [][]lst = new int[10][10];
for (int[] arr : lst) {
System.out.println(Arrays.toString(arr));
}
}
}

public static void printTwoDimensionalArray(int[][] a) {
for (int i = 0; i < a.length; i++) {
for (int j = 0; j < a[i].length; j++) {
System.out.printf("%d ", a[i][j]);
}
System.out.println();
}
}
just for int array

Well, since 'X' is a char and not an int, you cannot actually replace it in the matrix itself, however, the following code should print an 'x' char whenever it comes across a 1.
public void printGrid(int[][] in){
for(int i = 0; i < 20; i++){
for(int j = 0; j < 20; j++){
if(in[i][j] == 1)
System.out.print('X' + "\t");
else
System.out.print(in[i][j] + "\t");
}
System.out.print("\n");
}
}

You should loop by rows and then columns with a structure like
for ...row index...
for ...column index...
print
but I guess this is homework so just try it out yourself.
Swap the row/column index in the for loops depending on if you need to go across first and then down, vs. down first and then across.

How about trying this?
public static void main (String [] args)
{
int [] [] listTwo = new int [5][5];
// 2 Dimensional array
int x = 0;
int y = 0;
while (x < 5) {
listTwo[x][y] = (int)(Math.random()*10);
while (y <5){
listTwo [x] [y] = (int)(Math.random()*10);
System.out.print(listTwo[x][y]+" | ");
y++;
}
System.out.println("");
y=0;
x++;
}
}

If you know the maxValue (can be easily done if another iteration of the elements is not an issue) of the matrix, I find the following code more effective and generic.
int numDigits = (int) Math.log10(maxValue) + 1;
if (numDigits <= 1) {
numDigits = 2;
}
StringBuffer buf = new StringBuffer();
for (int i = 0; i < matrix.length; i++) {
int[] row = matrix[i];
for (int j = 0; j < row.length; j++) {
int block = row[j];
buf.append(String.format("%" + numDigits + "d", block));
if (j >= row.length - 1) {
buf.append("\n");
}
}
}
return buf.toString();

I am also a beginner and I've just managed to crack this using two nested for loops.
I looked at the answers here and tbh they're a bit advanced for me so I thought I'd share mine to help all the other newbies out there.
P.S. It's for a Whack-A-Mole game hence why the array is called 'moleGrid'.
public static void printGrid() {
for (int i = 0; i < moleGrid.length; i++) {
for (int j = 0; j < moleGrid[0].length; j++) {
if (j == 0 || j % (moleGrid.length - 1) != 0) {
System.out.print(moleGrid[i][j]);
}
else {
System.out.println(moleGrid[i][j]);
}
}
}
}
Hope it helps!

more simpler approach , use java 5 style for loop
Integer[][] twoDimArray = {{8, 9},{8, 10}};
for (Integer[] array: twoDimArray){
System.out.print(array[0] + " ,");
System.out.println(array[1]);
}