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q_learning.py

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+import numpy as np
+import pygame
+from time import time, sleep
+from random import randint
+import random
+
+# parameters of maze
+frame_interval = 0.1 # control run speed
+n = 4 # size of maze
+penalities = 4 # no. of red blocks
+
+# parameters of q learning
+alpha = 0.5 # learning rate
+gamma = 0.9 # discount factor
+epsilon = 1.0
+epsilon_delta = 0.0001
+
+# init maze
+current_pos = (0,0)
+reward = np.zeros((n,n))
+terminals = []
+
+background = (51,51,51)
+screen = pygame.display.set_mode(((2*n+1)*100,n*100))
+colors = [[background for i in range(n)] for j in range(n)]
+
+while penalities > 0:
+    i = randint(0,n-1)
+    j = randint(0,n-1)
+    if reward[i][j]==0 and (i,j)!=(0,0) and (i,j)!=(n-1,n-1):
+        reward[i][j] = -1
+        penalities -= 1
+        colors[i][j] = (255,0,0)
+        terminals.append((i,j))
+        
+reward[n-1][n-1] = 1
+colors[n-1][n-1] = (0,255,0)
+terminals.append((n-1,n-1))
+
+# init q learning
+Q = {}
+for i in range(n):
+    for j in range(n):
+        Q[(i,j)] = [0] * 4
+
+def select_action(pos):
+    if np.random.random() <= epsilon:
+        action = randint(0, 3)
+    else:
+        action = np.argmax(Q[tuple(pos)])
+    return action
+      
+def step():
+    
+    global current_pos, epsilon_delta, epsilon
+    #此处需要进行动作选取,给action赋值
+
+
+    new_pos = list(current_pos)
+    if action==0 and new_pos[0]>0: #move up
+        new_pos[0] -= 1
+    elif action==1 and new_pos[0]<n-1: #move down
+        new_pos[0] += 1
+    elif action==2 and new_pos[1]>0: #move left
+        new_pos[1] -= 1
+    elif action==3 and new_pos[1]<n-1: #move right
+        new_pos[1] += 1
+    new_pos = tuple(new_pos)
+
+    if new_pos not in terminals:
+        #此处实现Q-learning算法
+
+
+
+    else:
+        # 此处实现Q-learning算法
+
+
+
+        
+    if epsilon > 0.05:
+        epsilon -= epsilon_delta
+    current_pos = new_pos
+
+def layout():
+    for i in range(n):
+        for j in range(n):
+            pygame.draw.rect(screen, (255,255,255), (j*100,i*100,100,100), 0)
+            pygame.draw.rect(screen, colors[i][j], (j*100+3,i*100+3,94,94), 0)
+            pygame.draw.rect(screen, (255,255,255), ((j+n+1)*100,i*100,100,100), 0)
+            vij = max(Q[(i,j)])
+            qc = (0,int(255*vij),0) if vij>0 else (int(-255*vij),0,0)
+            pygame.draw.rect(screen, qc, ((j+n+1)*100+3,i*100+3,94,94), 0)
+    pygame.draw.circle(screen, (25,129,230), (current_pos[1]*100+50,current_pos[0]*100+50), 30, 0)
+      
+sleep_time = frame_interval
+running = True
+while running:
+    step()
+    sleep(sleep_time)
+    screen.fill(background)
+    layout()
+    for event in pygame.event.get():
+        if event.type == pygame.QUIT:
+            running = False
+        if event.type == pygame.KEYDOWN and event.key == pygame.K_SPACE:
+            sleep_time = 0 if sleep_time>0 else frame_interval
+    pygame.display.flip()
+pygame.quit()