160times iteration for gridworld.py

# @FileName ：
# 全局变量
states = [ i for i in range(16)]
values = [ 0 for _ in range(16)]
actions = ["n", "w", "e", "s"]
ds_actions = {"n":-4, "w":-1, "e":1, "s":4}
gamma = 0.95 # 一百次左右收敛

# gama = 1.00 # 150次左右收敛

# 根据当前的S，A确定下一步状态
def nextState(s, a):
    next_state = s
    if (((s + 1) % 4 == 0 and a == "e")) or ((s % 4 == 0 and a == "w")) \
            or (s < 4 and a == "n") or (s > 11 and a == "s"):
        pass
    else:
        ds = ds_actions[a]
        next_state = s + ds
    return next_state

def rewardOf(s):
    return 0 if s in [0,15] else -1

def isTerminateState(s):
    return s in [0,15]

# 获取某一状态下一步的可能状态空间
def getSuccessors(s):
    successors = []
    if isTerminateState(s):
        return successors  # 注意：该处直接跳出该子函数
    for a in actions:
        next_state = nextState(s,a)
        # if s ！= next_state:
        successors.append(next_state)
    return successors

# 根据后续状态更新某一状态值
def updateValue(s):
    successors = getSuccessors(s)
    newValue = 0
    nums = 4
    reward = rewardOf(s)
    for next_state in successors:
        newValue += - 1.00/nums * (reward + gamma * values[next_state])
    return newValue

def printValue(v):
    for i in range(16):
        print('{0:>2f}'.format(v[i]), end = " ")
        if (i + 1) % 4 == 0 :
            print(" ")
    print()


# 进行一次迭代
def performOneIteration():
    newValues = [ 0 for _ in range(16)]
    for s in states:
        newValues[s] = updateValue(s)
    global values
    values = newValues
    printValue(values)

# 在150左右收敛
def main():
    print('Hello')
    max_iterate_times = 160
    cur_iterate_times = 0
    while cur_iterate_times <= max_iterate_times:
        print('Iterate No.{0}'.format(cur_iterate_times))
        performOneIteration()
        cur_iterate_times +=1
    printValue(values)


if __name__ == '__main__':
    main()