Create 10 instances of an object (Python)

juicy

Hello Forum,

I got a question: First off: I'm using Python Mode. I'm trying to instantiate an object 10 times, but whatever i do ends up in the ellipses getting a tremendous speed boost. The idea is: Create 10 ellipses all spawning on different locations and with different velocity. Is this possible using lists? Here is the code, creating 1 instance of the object:

from BallTab import Ball

def setup():
    global myFirstBall
    size(800, 800)
    myFirstBall = Ball(random(50, 750), random(50, 750), 2, 3, 100)


def draw():
    global myFirstBall
    background(69, 69, 69) 
    myFirstBall.display()
    myFirstBall.move()
    if myFirstBall.y > 750:
        myFirstBall.ys = -2
    if myFirstBall.x > 750:
        myFirstBall.xs = -3
    if myFirstBall.y < 50:
        myFirstBall.ys = 2
    if myFirstBall.x < 50:
        myFirstBall.xs = 3

BallTab:

class Ball(object):
    def __init__(self, xPos, yPos, xSpeed, ySpeed, radius):
        self.x = xPos
        self.y = yPos
        self.xs = xSpeed
        self.ys = ySpeed
        self.r = radius

    def display(self):
        ellipse(self.x, self.y, self.r, self.r)

    def move(self):
        self.x += self.xs
        self.y += self.ys

jeremydouglass

@juicy -- Yes, adding things to lists is trivial in python. Just use loop over the range/xrange and use mylistname.append(myobject). Or use a list comprehension.

From Creating a list of objects in Python:

class MyClass(object):
    def __init__(self, number):
        self.number = number

my_objects = []

for i in range(100):
    my_objects.append(MyClass(i))

# later

for obj in my_objects:
    print obj.number

From other Creating a list of objects in Python:

class SimpleClass(object):
    pass
simplelist = []
for count in xrange(4):
    x = SimpleClass()
    x.attr = count
    simplelist.append(x)

juicy

It works now, thank you very much! If anyone wants to see the finished code, leave a reply!

jeremydouglass

Glad it worked out, @juicy!

Yes, I would love to see the finished code. I also think sharing your Python example with the forum would help new Processing.py learners.

laimperiestro

Hi Juicy

I am newbie here at Phyton, so I'd like to watch the fiinished code if you don't mind

Thanks

GoToLoop

Hi @jeremydouglass & @laimperiestro!

Given that @juicy didn't posted his final code yet, I remembered I had a very similar sketch from the previous old forum:
https://forum.Processing.org/one/topic/nullpointerexeption-with-an-arraylist

Its old online link too: :bz
http://studio.ProcessingTogether.com/sp/pad/export/ro.9oyKfI9kOIa77/latest

Made some refactoring in order to modernize it a bit more. 1st the Java Mode version:

/**
 * Clickable Spawning Balls (v3.1)
 * by  drov.fr  (2013/Jun)
 * mod GoToLoop (2013/Dec)
 * refactor ver (2016/Nov/27)
 *
 * forum.Processing.org/two/discussion/19200/
 * create-10-instances-of-an-object-python#Item_5
 *
 * forum.Processing.org/one/topic/nullpointerexeption-with-an-arraylist
 * forum.Processing.org/two/discussion/2171/effect-in-processing#Item_3
 *
 * studio.ProcessingTogether.com/sp/pad/export/ro.9oyKfI9kOIa77/latest
 * p5js.SketchPad.cc/sp/pad/view/ro.CwHWpJ$SP1EN8i/latest
 */

import java.util.List;
final List<Ball> balls = new ArrayList<Ball>();

static final color BG = 0;
static final boolean NO_JS = 1/2 != 1/2.;

void setup() {
  size(600, 400, NO_JS? FX2D : JAVA2D);
  smooth(3);
  frameRate(60);
  ellipseMode(CENTER);
  fill(Ball.COLOUR);
  noStroke();
}

void draw() {
  background(BG);
  for (final Ball b : balls)  b.script();
  if (NO_JS)  getSurface().setTitle( "# Balls: " + balls.size() );
}

void mousePressed() {
  if (mouseButton != CENTER)  balls.add( new Ball() );
  else {
    final int len = balls.size();
    if (len != 0)  balls.remove(len - 1);
  }
}

final class Ball {
  static final byte  DIAM = 20, RAD = DIAM >> 1;
  static final byte  MIN_SPD = 1, MAX_SPD = 5 + 1;
  static final color COLOUR  = #FFFF00;

  short x, y;
  byte  spX, spY;

  Ball() {
    x = (short) mouseX;
    y = (short) mouseY;

    spX = (byte) random(MIN_SPD, MAX_SPD);
    if (random(1) < .5)  spX *= -1;

    spY = (byte) ( random(MIN_SPD, MAX_SPD) *
      (random(1) < .5? -1 : 1) );
  }

  void script() {
    bump();
    show();
  }

  void bump() {
    if ( (x += spX) < RAD | x > width - RAD )  spX *= -1;
    y += spY *= y < RAD | y > height - RAD? -1 : 1;
  }

  void show() {
    ellipse(x, y, DIAM, DIAM);
  }
}

And finally, the corresponding Python Mode, so you all can compare them: :-bd

"""
 ' Clickable Spawning Balls (v3.1.1)
 ' by  drov.fr  (2013/Jun)
 ' mod GoToLoop (2013/Dec)
 ' Python ver.  (2016/Nov/27)
 '
 ' https://forum.Processing.org/two/discussion/19200/
 ' create-10-instances-of-an-object-python#Item_5
 '
 ' https://forum.Processing.org/one/topic/nullpointerexeption-with-an-arraylist
 ' https://forum.Processing.org/two/discussion/2171/effect-in-processing#Item_3
 '
 ' http://studio.ProcessingTogether.com/sp/pad/export/ro.9oyKfI9kOIa77/latest
 ' http://p5js.SketchPad.cc/sp/pad/view/ro.CwHWpJ$SP1EN8i/latest
"""

balls, BG = [], 0

def setup():
    size(600, 400, FX2D)
    smooth(3), frameRate(60)
    ellipseMode(CENTER), fill(Ball.COLOUR), noStroke()


def draw():
    background(BG)
    for b in balls: b.script()
    this.getSurface().setTitle('# Balls: ' + `len(balls)`)


def mousePressed():
    if mouseButton != CENTER: balls.append( Ball() )
    else: len(balls) and balls.pop()


class Ball:
    DIAM = 20
    RAD = DIAM >> 1
    MIN_SPD, MAX_SPD = 1, 5+1
    COLOUR = 0xffFFFF00

    def __init__(b):
        b.x, b.y = mouseX, mouseY

        b.spX = int( random( Ball.MIN_SPD, Ball.MAX_SPD ) )
        if random(1) < .5: b.spX *= -1

        b.spY = int( random( Ball.MIN_SPD, Ball.MAX_SPD ) *
                   ( random(1) < .5 and -1 or 1 ) )


    def script(b): b.bump(), b.show()

    def bump(b):
        b.x += b.spX
        if b.x < Ball.RAD or b.x > width - Ball.RAD: b.spX *= -1

        b.spY *= (b.y < Ball.RAD or b.y > height - Ball.RAD) and -1 or 1
        b.y += b.spY


    def show(b): ellipse(b.x, b.y, Ball.DIAM, Ball.DIAM)

juicy

Sorry for the late response. Been kind of busy! Here is my completed code (NOTE: Python):

Main:

from BallTab import Ball

def setup():
    global myFirstList
    size(800, 800)
    myFirstList = []

    for _ in range(0, 10):
        xPos = random(50, 750)
        yPos = random(50, 750)
        xSpeed = random(0, 5)
        ySpeed = random(0, 5)
        radius = 100
        col =  color(random(0, 255), random(0, 255), random(0, 255))
        print col
        myFirstList.append(Ball(xPos, yPos, xSpeed, ySpeed, radius, col))


def draw():
    global myFirstList
    background(69, 69, 69) 

    for _ in range(0, len(myFirstList)):
        myFirstList[_].move()
        myFirstList[_].display()

Tab: BallTab:

class Ball(object):
    def __init__(self, xPos, yPos, xSpeed, ySpeed, radius, col):
        self.x = xPos
        self.y = yPos
        self.xs = xSpeed
        self.ys = ySpeed
        self.r = radius
        self.col = col

    def display(self):
        fill(self.col)
        ellipse(self.x, self.y, self.r, self.r)

    def move(self):
        self.x += self.xs
        self.y += self.ys
        if self.y > 750:
            self.ys = -2
        if self.x > 750:
            self.xs = -3
        if self.y < 50:
            self.ys = 2
        if self.x < 50:
            self.xs = 3

kfrajer

Thxs @juicy and @GoToLoop

GoToLoop

Since I've already coded versions for Java & Python modes, why not for p5.js as well? :-bd
http://p5js.SketchPad.cc/sp/pad/view/ro.CwHWpJ$SP1EN8i/latest

/**
 * Clickable Spawning Balls (v3.1)
 * by  drov.fr  (2013/Jun)
 * mod GoToLoop (2013/Dec)
 * refactor ver (2016/Nov/30)
 *
 * forum.Processing.org/two/discussion/19200/
 * create-10-instances-of-an-object-python#Item_8
 *
 * forum.Processing.org/one/topic/nullpointerexeption-with-an-arraylist
 * forum.Processing.org/two/discussion/2171/effect-in-processing#Item_3
 *
 * p5js.SketchPad.cc/sp/pad/view/ro.CwHWpJ$SP1EN8i/latest
 * studio.ProcessingTogether.com/sp/pad/export/ro.9oyKfI9kOIa77/latest
 */

"use strict";

const balls = [];
let bg;

function setup() {
  createCanvas(600, 400).mouseClicked(() => {
    if (mouseButton != CENTER)  balls.push( new Ball );
    else balls.length && --balls.length;
  });

  frameRate(60).ellipseMode(CENTER).blendMode(REPLACE);
  fill(Ball.COLOUR).noStroke();

  bg = color(0);
}

function draw() {
  background(bg);
  for (let b of balls)  b.script();
  document.title = '# Balls: ' + balls.length;
}

class Ball {
  constructor() {
    this.x = mouseX, this.y = mouseY;

    this.spX = ~~random( Ball.MIN_SPD, Ball.MAX_SPD );
    random(1) < .5 && (this.spX *= -1);

    this.spY = ( ~~random( Ball.MIN_SPD, Ball.MAX_SPD ) *
               ( random(1) < .5 && -1 || 1 ) );
  }

  script() {
    this.bump(), this.show();
  }

  bump() {
    (this.x += this.spX)<Ball.RAD | this.x>width-Ball.RAD && (this.spX *= -1);
    this.y += this.spY *= this.y<Ball.RAD | this.y>height-Ball.RAD && -1 || 1;
  }

  show() {
    ellipse(this.x, this.y, Ball.DIAM, Ball.DIAM);
  }
}

Ball.DIAM = 20, Ball.RAD = Ball.DIAM >> 1;
Ball.MIN_SPD = 1, Ball.MAX_SPD = 5 + 1;
Ball.COLOUR = 'yellow';

jeremydouglass

Thanks to you both. Having a side-by-side examples of multiple objects in Java mode, Python mode, and p5.js seems really useful -- a kind of "Rosetta Stone" for the learning community.