I wrote this simple particle flow animation with Tkinter. I wanted to ask if there is some major improvements you can think of regarding the animation motor or the documentation of my code? I noticed that sometimes the "Stop animation" functionality takes some time to run but I don't know how to improve it.

This is an uni course project and later we will add some user inputs (radius and length of the pipe, pressure difference and flow liquid) and implement calculations for the speeds of the rows. Possibly changing the colour of the particles also depending on the flow liquid. This is why I'm deleting the particles and drawing them again when "Stop animation" is pressed.

Below you can see the code of my animation.

from tkinter import *

size = 15
gap = 5
columns = 25
rows = 7

downspace = 40  # space for the buttons below the animation
screenwidth = columns*size + (columns-2)*gap
screenheight = rows*size + rows*gap + downspace

color = "sky blue"
xspeed = [2, 3, 4, 5, 4, 3, 2]  # list for the speeds of the particle rows

class Animation:
    """Class for the animation and buttons"""

    def __init__(self):
        Creates the canvas, lines, buttons and runs the mainloop of the tkinter window
        self.particlelist is a list for the rows of particles

        self.root = Tk()
        self.canvas = Canvas(self.root, width=screenwidth, height=screenheight)

        self.root.title("Laminar flow in a pipe")
        self.canvas.create_line(0, gap, screenwidth, gap, width=2)
        self.canvas.create_line(0, rows*size + (rows+2)*gap, screenwidth, rows*size + (rows+2)*gap, width=2)

        self.particlelist = []

        self.stop_animation = False
        self.start = Button(self.root, text="Start animation", command=self.start_anim)
        self.stop = Button(self.root, text="Stop animation", command=self.stop_anim)


    def start_anim(self):
        """Starts the animation"""

        self.stop_animation = False

    def stop_anim(self):
        Stops the animation and deletes the particles
        Runs the function init to draw new particles to the beginning positions

        self.stop_animation = True

        for i in range(len(self.particlelist)):
            xlist = self.particlelist[i]
            for particle in xlist:
            self.particlelist[i] = []


    def init(self):
        Creates lists of particle rows and appends them to self.particlelist

            * ypos: vertical postition of the particle
            * xpos: horizontal position of the particle

        ypos = 10
        for i in range(rows):
            xpos = 0
            xlist = []

            for t in range(columns):
                xlist.append(Particle(self.canvas, xpos, ypos, color, xspeed[i]))
                xpos += size + gap

            ypos += size + gap

    def update(self):
        Updates the screen
            * t: update interval in milliseconds

        t = 20

        if self.stop_animation == False:
            for i in range(len(self.particlelist)):
                xlist = self.particlelist[i]
                for particle in xlist:

            self.canvas.after(t, self.update)

class Particle():
    Class for particles

        * canvas: canvas from the class "Animation"
        * xpos: x coordinate for creation of the shape
        * ypos: y coordinate for creation of the shape
        * color: fill color of the shape
        * xspeed: speed of the shape to the horizontal direction

    def __init__(self, canvas, xpos, ypos, color, xspeed):
        self.canvas = canvas
        self.shape = self.canvas.create_oval(xpos, ypos, xpos+size, ypos+size, fill=color)
        self.xspeed = xspeed

    def move(self):
        Function for moving the shape.

            * "pos" gives a vector of position [x0, y0, x1, y1] where 0 is the left upper corner
              and 1 is the right down corner of the shape

        self.canvas.move(self.shape, self.xspeed, 0)
        pos = self.canvas.coords(self.shape)

        if pos[0] >= screenwidth:     # returning the shape to the left side of the screen
            overlap = (pos[0] - screenwidth)
            self.canvas.coords(self.shape, gap-size+overlap, pos[1], gap+overlap, pos[3])

    def delete(self):
        """Function for deleting the shape"""



Any comments are appreciated!

  • \$\begingroup\$ Thanks a lot for posting this, it served as a good starting point into my [own project]:(github.com/tpo/flow). As a critique of your code I'd propose to disambiguate symbols. I have added a "step" button to my project. That also calls "update", however it doesn't schedule the next automatic update. So I've renamed the "update" method to "step". "step" will schedule the next step if "self.loop" is set (which is ugly and calls for further refactoring). So the next rename would be "self.stop_animation" to "self.loop", which also changes semantics and makes them clearer. \$\endgroup\$ – Tomáš Pospíšek Sep 22 '19 at 11:15

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