ceating grid using single loop or without nested loop?

xenomorph

I know you can create grids using nested loops

for(int i=0;i<3;i++){
    for(int j=0;j<2;j++){
       rect(i*w,j*h,w,h);
    }
}

Can we create same grid with just one loop, no nested loop?

   for(int i=0;i<6;i++){
      rect(w*i%3,h*i%2,w,h);
   }

koogs

Use i % columns for x and i / columns for y. So here that would be

rect(w * (i % 3), h * (i / 3), w, h);

The / is using integer division here, you don't want it to return a fractional value, so i should be an int. I've added brackets to make it clearer and to rule out it returning a fractional value should h be a float.

GoToLoop

W/o parenthesis: rect(i%3 * w, i/3 * h, w, h); :ar!

xenomorph

I am stupid! Thanks @Koogs :) :)

GoToLoop thank you too for correct :) :)

koogs

Don't rely on operator precedence for stuff like this. It is cryptic and it'll bite you sooner or later.

GoToLoop

The modulo (A.K.A. remainder) % operator, b/c it's related to the division / operator, it's got its same precedence, along w/ the multiplication * operator, like we've all learnt from actual math! :P

jeremydouglass

Hmm. For most people -- especially in a community with beginners in one or more languages -- I think it is better that they be really clear and not assume they have internalized Java operator precedence. Especially in a community with Java, JavaScript, Python, Ruby, and R flavors et cetera.

Here are operator precedence descriptions for ~60 languages, and while the whole extended C family is mostly the same on the basics, gotchas abound....

• https://rosettacode.org/wiki/Operator_precedence

Bonus code golf game: Operator precedence: How wrong can I be?

GoToLoop

... and not assume they have internalized Java operator precedence.

@jeremydouglass, addition, subtraction, multiplication & division's precedence is learned at basic school. :-B

Just a lil' twist that the modulo (remainder) operator is related to division. ;;)

jeremydouglass

I think that % twist is the whole point.

If you are expected to put А В Б in order, it doesn't matter that you learned A B in grade school. If you don't know one of them, you don't know the order.

I'm not against people learning, of course. I'm just saying you can't assume that Oracle's operator precedence table should be intuitive or common knowledge for people with basic math.

Chrisir

I think using a nested for loop in setup() and putting the data into an array of a class Cell that holds the position and values of the cells is the best approach

I personally think the code with nested for loop has a better readability than % stuff anyway ..... and for me readability and maintainability have priority in writing code.

Chrisir

Cell [] grid;



// ---------------------------------------------------------

void setup() {  
  size(400, 400);
  noStroke();
  background(255);

  String[] list = {"b", "c", "d", "q"};
  int unit = 200; // size of one tile
  int wideCount = width / unit;
  int highCount = height / unit; 
  int count = wideCount * highCount;

  grid = new Cell[count];

  int index = 0;
  for (int x=0; x < wideCount; x++) {
    for (int y=0; y < highCount; y++) {
      //start creating objects
      grid[index] = new Cell (x*unit, y*unit, unit, list[index]);
      index++;
    }
  }
}

void draw() {

  background(255);

  for (int i=0; i < grid.length; i++) {
    grid[i].display();
  }
}

// ========================================================================
// and the class


class Cell {
  float x, y;
  float side;  // size 
  String text=""; 

  Cell (float tempX, float tempY, 
    float tempSide, 
    String tempText) {
    x = tempX;
    y = tempY;
    side = tempSide;
    text = tempText; 
    //
    float fate = random(2);
  }

  void display() {
    if (mouseX>x&&
      mouseX<x+side&&
      mouseY>y&&
      mouseY<y+side)
      fill(122, 0, 0); // dark
    else
      fill(255, 0, 0);  // light 

    stroke(255);
    rect (x, y, side, side);

    fill(255); 
    text(text, x+55, y+60);
  }
}

jeremydouglass

Fair enough -- I suppose the whole point of doing it in a single loop, or with no parens, or in as few chars as possible is "can this work?" -- and not trying to find the most readable or maintainable solution.

Chrisir

;-)

monkstone

In jruby_art and propane we have created a grid convenience method after Nodebox it is both really convenient and efficient.

Chrisir

thanks I just edited my post above with some code example

koogs

74 lines of code answering a question that wasn't asked. 8)

you people must have so much spare time.