QR Codes and the Game of Life

pip install opencv-python
pip install numpy
pip install scipy
pip install matplotlib

$ python qrlife.py qr-photo.jpg

import sys
import cv2
import numpy as np
from scipy.signal import convolve2d
import matplotlib.pyplot as plt
from matplotlib import animation

class Life:
    """A Game of Life simulator."""

    def __init__(self, arr, pad=25):
        """Initialize the instance.

        The provided array consists of zero and non-zero entries,
        representing dead and alive cells, respectively. It is optionally
        padded by width pad on all sides with zeros.

        """

        # Set the "world" array as boolean and initialize the figure.
        # The world is depicted as a black-and-white array of squares.
        self.arr = arr.astype(bool)
        self.arr = np.pad(self.arr, pad)

        self.fig, self.ax = plt.subplots()
        self.im = self.ax.imshow(self.arr, cmap=plt.cm.binary,
                                 interpolation='nearest')
        # Remove the Axes tick marks.
        self.ax.set_xticks([])
        self.ax.set_yticks([])

    def do_step(self):
        """Advance the Game of Life world by one generation."""

        # Use convolution method to count neighbours, e.g.
        # http://jakevdp.github.io/blog/2013/08/07/conways-game-of-life/
        nn = convolve2d(self.arr, np.ones((3, 3)), mode='same',
                        boundary='wrap') - self.arr
        self.arr = (nn == 3) | (self.arr & (nn == 2))

    def init_animation(self):
        """Initialize the animation: self.im is updated on each time step."""

        self.im.set_data(np.zeros_like(self.arr))
        return self.im,

    def animate(self, i):
        """Draw the current state of the world and advance by one time step."""

        self.im.set_data(self.arr)
        self.do_step()

    def play(self, frames=1000, interval=100):
        """Play the Game of Life, depicted as a Matplotlib animation."""

        anim = animation.FuncAnimation(self.fig, self.animate,
                    init_func=self.init_animation, frames=frames,
                    interval=interval)
        # If we're saving the animation as a video, uncomment these two lines.
        #writer = animation.FFMpegWriter(fps=4)
        #anim.save('life.mp4', writer=writer)

        # If we're just viewing the animation locally, uncomment this line.
        plt.show()

if __name__ == "__main__":
    # Read the image filename from the command line and detect the QR code.
    qr_image = sys.argv[1]
    image = cv2.imread(qr_image)
    detector = cv2.QRCodeDetector()
    value, points, arr = detector.detectAndDecode(image)
    # Print the "value" of the QR code (e.g. the URL it encodes).
    print(f'QR code with dimensions {arr.shape} detected.')
    print('QR value:', value)

    life = Life(arr)
    life.play()