#encoding:utf-8

from random import choice
import matplotlib.pyplot as plt

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的点'''

        #不断漫步，直到列表达到指定的长度
        while len(self.x_values) < self.num_points:
            x_step = self.get_walk()
            y_step = self.get_walk()

            #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)

    def get_walk(self):
        direction = choice([1, -1])
        distance = choice([0, 1, 2, 3, 4])
        step = direction * distance
        return step

while True:
    rw = RandomWalk()
    rw.fill_walk()

    #设置绘图窗口的尺寸
    plt.figure(dpi = 128, figsize = (10, 6))    #dpi为分辨率，figsize为窗口尺寸

    #绘制点并将图形显示出来
    point_numbers = list(range(rw.num_points))
    plt.scatter(rw.x_values, rw.y_values, c = point_numbers, cmap = plt.cm.Blues, edgecolor = 'none', s = 1)
    plt.scatter(0, 0, c = 'green', edgecolors = 'none', s = 100)      #重新绘制起点和终点
    plt.scatter(rw.x_values[-1], rw.y_values[-1], c = 'green', edgecolors = 'none', s = 100)

    #隐藏坐标轴
    plt.axes().get_xaxis().set_visible(False)
    plt.axes().get_yaxis().set_visible(False)

    plt.show()

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