0、相关文章

1、导入所使用的包

# 导入所使用的包
import numpy as np
import matplotlib.pyplot as plt

2、定义迷宫

fig = plt.figure(figsize=(5, 5))
ax = plt.gca()

# 画出红色的墙壁
plt.plot([1, 1], [0, 1], color='red', linewidth=2)
plt.plot([1, 2], [2, 2], color='red', linewidth=2)
plt.plot([2, 2], [2, 1], color='red', linewidth=2)
plt.plot([2, 3], [1, 1], color='red', linewidth=2)

# 画出表示状态的文字S0-S8
plt.text(0.5, 2.5, 'S0', size=14, ha='center')
plt.text(1.5, 2.5, 'S1', size=14, ha='center')
plt.text(2.5, 2.5, 'S2', size=14, ha='center')
plt.text(0.5, 1.5, 'S3', size=14, ha='center')
plt.text(1.5, 1.5, 'S4', size=14, ha='center')
plt.text(2.5, 1.5, 'S5', size=14, ha='center')
plt.text(0.5, 0.5, 'S6', size=14, ha='center')
plt.text(1.5, 0.5, 'S7', size=14, ha='center')
plt.text(2.5, 0.5, 'S8', size=14, ha='center')
plt.text(0.5, 2.3, 'START', ha='center')
plt.text(2.5, 0.3, 'GOAL', ha='center')

# 设定画图的范围
ax.set_xlim(0, 3)
ax.set_ylim(0, 3)
ax.set_title("Random")
plt.tick_params(axis='both', which='both', bottom='off', top='off',
                labelbottom='off', right='off', left='off', labelleft='off')

# 当前位置S0用绿色圆圈画出
line, = ax.plot([0.5], [2.5], marker="o", color='g', markersize=60)

3、定义迷宫动作

# 设定参数θ的初始值theta_0,用于确定初始方案

# 行为状态0~7，列为用↑、→、↓、←表示的移动方向
theta_0 = np.array([[np.nan, 1, 1, np.nan],  # s0
                    [np.nan, 1, np.nan, 1],  # s1
                    [np.nan, np.nan, 1, 1],  # s2
                    [1, 1, 1, np.nan],  # s3
                    [np.nan, np.nan, 1, 1],  # s4
                    [1, np.nan, np.nan, np.nan],  # s5
                    [1, np.nan, np.nan, np.nan],  # s6
                    [1, 1, np.nan, np.nan],  # s7、※s8是目标，无策略
                    ])

效果：
迷宫随机实验

4、策略参数θ转换为行动策略π

def simple_convert_into_pi_from_theta(theta):
    '''简单计算百分比'''

    [m, n] = theta.shape  # 获取theta矩阵大小
    pi = np.zeros((m, n))
    for i in range(0, m):
        pi[i, :] = theta[i, :] / np.nansum(theta[i, :])  # 计算百分比

    pi = np.nan_to_num(pi)  # 将nan转换为0

    return pi

5、定义随机移动函数

# 1步移动后求得状态s
def get_next_s(pi, s):
    direction = ["up", "right", "down", "left"]
    
    # 根据概率pi[s,:]选择direction
    next_direction = np.random.choice(direction, p=pi[s, :])

    # 移动后切换状态
    if next_direction == "up":
        s_next = s - 3 
    elif next_direction == "right":
        s_next = s + 1  
    elif next_direction == "down":
        s_next = s + 3  
    elif next_direction == "left":
        s_next = s - 1  

    return s_next

6、定义使智能体移动到目标的函数

def goal_maze(pi):
    s = 0  # 开始地点
    state_history = [0]  # 记录智能体移动轨迹的列表

    while (1):  # 循环，直至到达目标
        next_s = get_next_s(pi, s)
        state_history.append(next_s)

        if next_s == 8:  # 到达目标地点则终止
            for i in range(0,10):
                state_history.append(next_s)
            break
        else:
            s = next_s

    return state_history

7、智能体移动到目标

# 求初始策略π
pi_0 = simple_convert_into_pi_from_theta(theta_0)
state_history = goal_maze(pi_0)
print(state_history)
print("求解迷宫问题所需要的步数是：" + str(len(state_history) - 1))

8、运行路径可视化

# 参考URL http://louistiao.me/posts/notebooks/embedding-matplotlib-animations-in-jupyter-notebooks/
from matplotlib import animation
from IPython.display import HTML

def init():
    '''初始化背景图像'''
    line.set_data([], [])
    return (line,)

def animate(i):
    '''每一帧的画面内容'''
    state = state_history[i]  # 画出当前的位置
    x = (state % 3) + 0.5  # 状态的x坐标为状态数除以3的余数加0.5
    y = 2.5 - int(state / 3)  # 状态y坐标为2.5减去状态数除以3的商
    line.set_data(x, y)
    return (line,)

#　用初始化函数和绘图函数来生成动画
anim = animation.FuncAnimation(fig, animate, init_func=init, frames=len(
    state_history), interval=200, repeat=False)

anim.save('result/maze_Random.gif',writer='pillow')
HTML(anim.to_jshtml())