Draw many circles using Arrays and For Loops

mySketch
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// Variable for number of total circles so we can change it easily
int numCircs = 100;
​
// Arrays for randomising the location of the circles 
float[] circX = new float[numCircs];
float[] circY = new float[numCircs];
float[] circD = new float[numCircs];
​
// Array for randomising the color of the circle using the color datatype - like int, String etc. 
color[] circColor = new color[numCircs];
​
void setup() {
  size(500, 800);
 // noStroke();
  // Create all these circles at random places all over the screen! 
  for (int i = 0; i<numCircs; i = i+1) {
    circX[i] = random(width);
    circY[i] = random(height);
    circD[i] = random(40);
    circColor[i] = color( random(255), random(255), random(255));
  }
}
​
void draw() {
  //background(#09366C);
  background(#51549B);
             
  // Change the colour of each circle on mouse hover
  for (int i = 0; i<numCircs; i++) {
    if (dist(mouseX, mouseY, circX[i], circY[i]) < circD[i]*.5) {
      fill(circColor[i]);
    } else {
      fill(255);
    }
    // draw the cirlces based our Arrays "circX, circY, circD" 
    // we apply the index counter to each part of the ellipse to randomize size, location etx.
    ellipse(circX[i], circY[i], circD[i], circD[i]);
  }
}
​
void keyPressed() {
  // when you press "R" reset all the locations of the circles 
  if (key == 'r') {
    for (int i = 0; i<numCircs; i++) {
      circX[i] = random(width);
      circY[i] = random(height);
      circD[i] = random(40) + 10;
      
      // Color of each ellipse is random 
      circColor[i] = color( random(255), random(255), random(255));
    }
  }
}