from random import choice

class RandomWalk():
  """一个生成随机漫步数据的类"""

  def __init__(self, num_points=50000):
    """初始化随机漫步的属性"""
    self.num_points = num_points

    # 所有随机漫步都始于(0,0)
    self.x_values = [0]
    self.y_values = [0]

def fill_walk(self):
    """计算随机漫步包含的所有点"""

    # 不断漫步，直到列表达到指定的长度
    while len(self.x_values) < self.num_points:
      # 决定前进方向以及沿这个方向前进的距离
      x_direction = choice([1,- 1])
      x_distance = choice([1, 2, 3, 4])
      x_step = x_direction * x_distance

      y_direction = choice([1, -1])
      y_distance = choice([1, 2, 3, 4])
      y_step = y_direction * y_distance

      # 拒绝原地踏步
      if x_step == 0 and y_step == 0:
        continue

      # 计算下一个点的x和y值
      next_x = self.x_values[-1] + x_step
      next_y = self.y_values[-1] + y_step

      self.x_values.append(next_x)
      self.y_values.append(next_y)

import matplotlib.pyplot as plt

from randomwalk import RandomWalk

# 只要程序处于活动状态，就不断地模拟随机漫步
while True:
  # 创建一个RandomWalk实列，并将其包含的点都绘制出来
  rw = RandomWalk()
  rw.fill_walk()

  plt.figure(dpi=128, figsize=(8, 4))

  point_numbers = list(range(rw.num_points))
  plt.scatter(rw.x_values, rw.y_values, c=point_numbers, cmap=plt.cm.Reds, edgecolors='none', s=1)
  # 突出起点和终点
  plt.scatter(0, 0, c='green', edgecolors='none', s=100)
  plt.scatter(rw.x_values[-1], rw.y_values[-1], c='red', edgecolors='none', s=100)
  plt.show()

  keep_running = input("Make another walk")
  if keep_running == 'n':
    break