Parte tres

void setup() {
  // initialize the I/O pins as outputs
  //initialize columns
  pinMode(6, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(3, OUTPUT);
  pinMode(17, OUTPUT);
  pinMode(4, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(9, OUTPUT);

  //initialize rows
  pinMode(2, OUTPUT);
  pinMode(7, OUTPUT);
  pinMode(19, OUTPUT);
  pinMode(5, OUTPUT);
  pinMode(13, OUTPUT);
  pinMode(18, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(16, OUTPUT);

  // initialize the pixel matrix:
  initializePixels();
  //digitalWrite(row[thisRow], LOW);

  //encendemos el led a la posicion 2x2
  digitalWrite(7, HIGH);
  digitalWrite(11, LOW);
  //Encendemos el LED a la posición 4x4
  digitalWrite(5, HIGH);
  digitalWrite(3, LOW); 
}

void loop() {

}
void initializePixels(){
  // 2-dimensional array of row pin numbers:
  const int row[8] = {
    2,7,19,5,13,18,12,16 };

  // 2-dimensional array of column pin numbers:
  const int col[8] = {
    6,11,10,3,17,4,8,9  };

  // 2-dimensional array of pixels:
  int pixels[8][8];           
    // initialize the pixel matrix:
  for (int x = 0; x < 8; x++) {
    for (int y = 0; y < 8; y++) {
      pixels[x][y] = HIGH;
    }
  }
  refreshScreen();
}

// 2-dimensional array of row pin numbers:
const int row[8] = {
  2,7,19,5,13,18,12,16 };

// 2-dimensional array of column pin numbers:
const int col[8] = {
  6,11,10,3,17,4,8,9  };
  
int pixels[8][8];

void refreshScreen() {
  // iterate over the rows (anodes):
  for (int thisRow = 0; thisRow < 8; thisRow++) {
    // take the row pin (anode) high:
    digitalWrite(row[thisRow], HIGH);
    // iterate over the cols (cathodes):
    for (int thisCol = 0; thisCol < 8; thisCol++) {
      // get the state of the current pixel;
      int thisPixel = pixels[thisRow][thisCol];
      // when the row is HIGH and the col is LOW,
      // the LED where they meet turns on:
      digitalWrite(col[thisCol], thisPixel);
      // turn the pixel off:
      if (thisPixel == LOW) {
        digitalWrite(col[thisCol], HIGH);
      }
    }
    // take the row pin low to turn off the whole row:
    digitalWrite(row[thisRow], LOW);
  }
}