mirror of
https://github.com/TheAlgorithms/Python.git
synced 2024-10-06 05:39:30 +00:00
107 lines
3.4 KiB
Python
107 lines
3.4 KiB
Python
"""
|
|
Langton's ant
|
|
|
|
@ https://en.wikipedia.org/wiki/Langton%27s_ant
|
|
@ https://upload.wikimedia.org/wikipedia/commons/0/09/LangtonsAntAnimated.gif
|
|
"""
|
|
|
|
from functools import partial
|
|
|
|
from matplotlib import pyplot as plt
|
|
from matplotlib.animation import FuncAnimation
|
|
|
|
WIDTH = 80
|
|
HEIGHT = 80
|
|
|
|
|
|
class LangtonsAnt:
|
|
"""
|
|
Represents the main LangonsAnt algorithm.
|
|
|
|
>>> la = LangtonsAnt(2, 2)
|
|
>>> la.board
|
|
[[True, True], [True, True]]
|
|
>>> la.ant_position
|
|
(1, 1)
|
|
"""
|
|
|
|
def __init__(self, width: int, height: int) -> None:
|
|
# Each square is either True or False where True is white and False is black
|
|
self.board = [[True] * width for _ in range(height)]
|
|
self.ant_position: tuple[int, int] = (width // 2, height // 2)
|
|
|
|
# Initially pointing left (similar to the wikipedia image)
|
|
# (0 = 0° | 1 = 90° | 2 = 180 ° | 3 = 270°)
|
|
self.ant_direction: int = 3
|
|
|
|
def move_ant(self, axes: plt.Axes | None, display: bool, _frame: int) -> None:
|
|
"""
|
|
Performs three tasks:
|
|
1. The ant turns either clockwise or anti-clockwise according to the colour
|
|
of the square that it is currently on. If the square is white, the ant
|
|
turns clockwise, and if the square is black the ant turns anti-clockwise
|
|
2. The ant moves one square in the direction that it is currently facing
|
|
3. The square the ant was previously on is inverted (White -> Black and
|
|
Black -> White)
|
|
|
|
If display is True, the board will also be displayed on the axes
|
|
|
|
>>> la = LangtonsAnt(2, 2)
|
|
>>> la.move_ant(None, True, 0)
|
|
>>> la.board
|
|
[[True, True], [True, False]]
|
|
>>> la.move_ant(None, True, 0)
|
|
>>> la.board
|
|
[[True, False], [True, False]]
|
|
"""
|
|
directions = {
|
|
0: (-1, 0), # 0°
|
|
1: (0, 1), # 90°
|
|
2: (1, 0), # 180°
|
|
3: (0, -1), # 270°
|
|
}
|
|
x, y = self.ant_position
|
|
|
|
# Turn clockwise or anti-clockwise according to colour of square
|
|
if self.board[x][y] is True:
|
|
# The square is white so turn 90° clockwise
|
|
self.ant_direction = (self.ant_direction + 1) % 4
|
|
else:
|
|
# The square is black so turn 90° anti-clockwise
|
|
self.ant_direction = (self.ant_direction - 1) % 4
|
|
|
|
# Move ant
|
|
move_x, move_y = directions[self.ant_direction]
|
|
self.ant_position = (x + move_x, y + move_y)
|
|
|
|
# Flip colour of square
|
|
self.board[x][y] = not self.board[x][y]
|
|
|
|
if display and axes:
|
|
# Display the board on the axes
|
|
axes.get_xaxis().set_ticks([])
|
|
axes.get_yaxis().set_ticks([])
|
|
axes.imshow(self.board, cmap="gray", interpolation="nearest")
|
|
|
|
def display(self, frames: int = 100_000) -> None:
|
|
"""
|
|
Displays the board without delay in a matplotlib plot
|
|
to visually understand and track the ant.
|
|
|
|
>>> _ = LangtonsAnt(WIDTH, HEIGHT)
|
|
"""
|
|
fig, ax = plt.subplots()
|
|
# Assign animation to a variable to prevent it from getting garbage collected
|
|
self.animation = FuncAnimation(
|
|
fig, partial(self.move_ant, ax, True), frames=frames, interval=1
|
|
)
|
|
plt.show()
|
|
|
|
|
|
if __name__ == "__main__":
|
|
import doctest
|
|
|
|
doctest.testmod()
|
|
|
|
LangtonsAnt(WIDTH, HEIGHT).display()
|