GridEnv环境代码

直接上代码
emmm 就算是强化学习的HelloWorld了吧

import logging
import numpy
import random
from gym import spaces
import gym

class GridEnv():
    metadata = {
        'render.modes': ['human', 'rgb_array'],
        'video.frames_per_second': 2
    }

    def __init__(self):
        # render 中
        self.x=[140,220,300,380,460,140,300,460]
        self.y=[250,250,250,250,250,150,150,150]    


        # 状态空间
        self.states = [1,2,3,4,5,6,7,8]
        # 动作空间
        self.actions = ['n','e','s','w']
        # 终止状态为字典格式
        self.terminate_states = dict()  
        self.terminate_states[6] = 1
        self.terminate_states[7] = 1
        self.terminate_states[8] = 1

        # 回报函数
        self.rewards = dict()
        self.rewards['1_s'] = -1.0
        self.rewards['3_s'] = 1.0
        self.rewards['5_s'] = -1.0

        # 状态转移概率
        self.t = dict()
        self.t['1_s'] = 6 
        self.t['1_e'] = 2 
        self.t['2_w'] = 1 
        self.t['2_e'] = 3 
        self.t['3_s'] = 7 
        self.t['3_w'] = 2 
        self.t['3_e'] = 4 
        self.t['4_w'] = 3 
        self.t['4_e'] = 5 
        self.t['5_s'] = 8 
        self.t['5_w'] = 4

        self.gamma = 0.8         #折扣因子
        self.viewer = None
        self.state = None

    def _step(self, action):
        # 获取当前系统状态
        state = self.state
        if state in self.terminate_states: 
            return state, 0, True, {}

        key = "%d_%s"%(state, action)

        #状态转移 
        if key in self.t:
            next_state = self.t[key]
        else:
            next_state = state
        self.state = next_state
        is_terminal = False
        if next_state in self.terminate_states:
            is_terminal = True

        if key not in self.rewards:
            r = 0.0
        else :
            r = self.rewards[key]
        return next_state,r,is_terminal,{}


    # 绘图贼简单- -
    def _render(self, mode='human', close=False):
        if close:
            if self.viewer is not None:
                self.viewer.close()
                self.viewer = None
            return
        screen_width = 600
        screen_height = 400

        if self.viewer is None:
            from gym.envs.classic_control import rendering
            self.viewer = rendering.Viewer(screen_width, screen_height)
            #创建网格世界
            self.line1 = rendering.Line((100,300),(500,300))
            self.line2 = rendering.Line((100, 200), (500, 200))
            self.line3 = rendering.Line((100, 300), (100, 100))
            self.line4 = rendering.Line((180, 300), (180, 100))
            self.line5 = rendering.Line((260, 300), (260, 100))
            self.line6 = rendering.Line((340, 300), (340, 100))
            self.line7 = rendering.Line((420, 300), (420, 100))
            self.line8 = rendering.Line((500, 300), (500, 100))
            self.line9 = rendering.Line((100, 100), (180, 100))
            self.line10 = rendering.Line((260, 100), (340, 100))
            self.line11 = rendering.Line((420, 100), (500, 100))
            #创建第一个骷髅
            self.kulo1 = rendering.make_circle(40)
            self.circletrans = rendering.Transform(translation=(140,150))
            self.kulo1.add_attr(self.circletrans)
            self.kulo1.set_color(0,0,0)
            #创建第二个骷髅
            self.kulo2 = rendering.make_circle(40)
            self.circletrans = rendering.Transform(translation=(460, 150))
            self.kulo2.add_attr(self.circletrans)
            self.kulo2.set_color(0, 0, 0)
            #创建金条
            self.gold = rendering.make_circle(40)
            self.circletrans = rendering.Transform(translation=(300, 150))
            self.gold.add_attr(self.circletrans)
            self.gold.set_color(1, 0.9, 0)
            #创建机器人
            self.robot= rendering.make_circle(30)
            self.robotrans = rendering.Transform()
            self.robot.add_attr(self.robotrans)
            self.robot.set_color(0.8, 0.6, 0.4)

            self.line1.set_color(0, 0, 0)
            self.line2.set_color(0, 0, 0)
            self.line3.set_color(0, 0, 0)
            self.line4.set_color(0, 0, 0)
            self.line5.set_color(0, 0, 0)
            self.line6.set_color(0, 0, 0)
            self.line7.set_color(0, 0, 0)
            self.line8.set_color(0, 0, 0)
            self.line9.set_color(0, 0, 0)
            self.line10.set_color(0, 0, 0)
            self.line11.set_color(0, 0, 0)

            self.viewer.add_geom(self.line1)
            self.viewer.add_geom(self.line2)
            self.viewer.add_geom(self.line3)
            self.viewer.add_geom(self.line4)
            self.viewer.add_geom(self.line5)
            self.viewer.add_geom(self.line6)
            self.viewer.add_geom(self.line7)
            self.viewer.add_geom(self.line8)
            self.viewer.add_geom(self.line9)
            self.viewer.add_geom(self.line10)
            self.viewer.add_geom(self.line11)
            self.viewer.add_geom(self.kulo1)
            self.viewer.add_geom(self.kulo2)
            self.viewer.add_geom(self.gold)
            self.viewer.add_geom(self.robot)

        if self.state is None: return None
        #self.robotrans.set_translation(self.x[self.state-1],self.y[self.state-1])
        self.robotrans.set_translation(self.x[self.state-1], self.y[self.state- 1])



        return self.viewer.render(return_rgb_array=mode == 'rgb_array')

    def _reset(self):
        self.state = self.states[int (random.random()*len(self.states))]
        return self.state码片

首先代码中主要有这几部分函数
函数中的self应该不是参数，就是本身对象的意思吧(原谅我从Java来到python不太熟悉语法)，除了self其他的应该就是参数了。

init(self)

初始化方法，其中定义的主要是环境的一些常量，包括环境必需的常量以及回报等等，貌似复杂的环境回报这些可能需要用函数式来表达

_step(self, action)

行为的方法，传入的参数action是在S下，执行的a，这里主要是仿真的过程，然后返回的值是
next_state,r,is_terminal,{}
下一个动作，回报，是否结束，最后这个数组这里没有写，等以后的环境遇到了再补充

_render(self, mode=‘human’, close=False)

这个函数对于强化学习应该没什么用，主要是用来显示界面的

_reset(self):

这个函数是对环境的初始化方法

总结

仔细一看，对环境的仿真首先要知道环境中的变量有哪些，然后用step函数实现在不同的动作下这些变量发生了什么样的变化。

书上的习题4有一个迷宫世界的环境，晚上尝试去实现一下