yeah to fill a 2D array you need a double for loop

1. for i .............
2. for  j ............
3. // do it
4. }
5. }

and "do it" boils down to

1. if (k<source.length) {
2. dest [i][j] = source [k];
3. k++;
4. }

Greetings, Chrisir

If you need an answer, please send me a personal message since this forum doesn't notify.

Hi  Chrisir,

Just to clarify the theory for ya

1. if (k<source.length) {
2. dest [i][j] = source [k];
3. k++;
4. }

So you iterate through every item in the source array. Let's say there are 9 items.
1 2 3 4 5 6 7 8 9
and you want
1 2 3
4 5 6
7 8 9

It's 3x3. I think you'll actually want your i loop on the inside, assuming you want left to right, to bottom. You can find k either with another loop or with j * (number of columns - 1) + i. So the first loop would be destination[0][0] = source[0], great. Second, destintation[1][0] = source[1] ... destination[2][1] = source[5] and so on.

Hopefully I didn't screw that up, it's coffee time. I get this question a lot, I know how much of a conceptual leap it can be.

Good luck!

What about this 1?:

final int ROWS = 4, COLS = 16, ELEMS = ROWS*COLS;

final float[] temps = new float[ELEMS];
final float[][] sensors = new float[ROWS][COLS];

for (int i=0; i!=ELEMS; temps[i++] = random(100));

println(temps);

for (int row=0; row!=ROWS; ++row)   for (int col=0; col!=COLS;
  sensors[row][col] = temps[row*COLS + col++]);

for (int row=0; row!=ROWS; 
  println("\nRow: #" + row), println(sensors[row++]));

exit();

Nice use of side effects.

I have implemented the approach prposed by  Chrisir in the following code.  It compiles, however it displays only "0's"a 4x16 matrix in both the Arduino and Processing serial monitors.

my approach must look like

1. for (i=0;i<ARRAYi;i++)
2. {
3. for (j=0;j<ARRAYj;j++)
4. {
5. if (k<source.length) {
6. dest [i][j] = source [k];
7. k++;
8. } // if
   
9. } // for
   
10. } // for
    
11. 
    

Greetings, Chrisir

If you need an answer, please send me a personal message since this forum doesn't notify.

here...





final int ARRAYi = 8;
int [] source = new int  [ARRAYi*ARRAYi];
int [][] dest = new int  [8][8];

size(800, 800);

print("source: ");
for (int i=0;i<source.length;i++)
{
  source [i] = int(random (64));
  print (source [i]+"  " );
}


println();

int k=0;
for (int j=0;j<ARRAYi;j++)
{
  for (int i=0;i<ARRAYi;i++)
  {

    if (k<source.length) {
      dest [i][j] = source [k];
      k++;
    } // if
  } // for
} // for

//  //
int colWidth = 26;
int rowHeight = 26;

// double for-loop for the 2D array
for (int j = 0; j < ARRAYi; j++) {
  for (int i = 0; i < ARRAYi; i++) {

    // what cell is it?
    //
    stroke(2, 2, 225); // blue
    fill(255);
    rect(i*colWidth+2+33, j*rowHeight+2+33, colWidth, rowHeight );
    fill(0);
    text (dest [i][j], i*colWidth+11+33, j*rowHeight+16+33 );
  } // for
} // for
//