给出一个python实现的MCTS算法代码

深碍√TFBOYSˉ_ 2024-03-25 16:15 43阅读 0赞

下面是一个简单的MCTS算法实现，使用Python语言实现：

\`\`\`python import math import random

class Node: def **init**(self, state, parent=None): self.state = state self.parent = parent self.children = \[\] self.wins = 0 self.visits = 0

def add_child(self, child_state):
        child = Node(child_state, self)
        self.children.append(child)
        return child
    
    def update(self, result):
        self.visits += 1
        self.wins += result
    
    def fully_expanded(self):
        return len(self.children) == len(self.state.get_moves())
    
    def __repr__(self):
        return "[M:" + str(self.wins/self.visits) + " W/V:" + str(self.wins) + "/" + str(self.visits) + "]"
    
    def tree_to_string(self, indent):
        s = self.indent_string(indent) + str(self)
        for c in self.children:
             s += c.tree_to_string(indent+1)
        return s
    
    def indent_string(self, indent):
        s = "\n"
        for i in range (1, indent+1):
            s += "| "
        return s
    
    def child_N(self):
        s = self.indent_string(1) + "children:" + "\n"
        for c in self.children:
            s += str(c.wins/c.visits) + ","
        return s

class MCTS: def **init**(self, state, itermax): self.itermax = itermax self.root = Node(state)

def search(self):
        for i in range(self.itermax):
            node = self.select_node(self.root)
            result = self.simulate(node)
            self.backpropagate(node, result)
        return self.get_best_child(self.root)
    
    def select_node(self, node):
        while not node.state.is_terminal():
            if not node.fully_expanded():
                return self.expand(node)
            else:
                node = self.get_best_child(node)
        return node
    
    def expand(self, node):
        tries = node.state.get_moves()
        for move in tries:
            if move not in [n.state for n in node.children]:
                new_node = node.add_child(node.state.do_move(move))
                return new_node
    
    def simulate(self, node):
        state = node.state
        while not state.is_terminal():
            state = state.do_move(random.choice(state.get_moves()))
        return state.get_result(node.state.player_just_moved)
    
    def backpropagate(self, node