Python Self TypeError:add_state（）只接受4个参数（给定3个参数）

Question

我试图用基于agent的仿真来解决stagecoach问题。我正在尝试将状态添加到Panda的数据帧中。但是，当我这样做的时候，我得到了一个错误“TypeError:add_state（）正好接受4个参数（给定3个）。”我查看了Stackoverflow上的其他问题并尝试了解决方案，但是有一点我遗漏了。在

有人能给我一些建议或提示，为什么我总是得到这个错误？谢谢你抽出时间。在

from __future__ import division
import random
import pandas as pd


class stagecoach():

    current_state = "A"
    home_state = "J"
    cost = 0

    index = range(1,20,1)
    columns = ["Current", "Choices", "Cost"]

    states = pd.DataFrame(columns=columns, index=index)

    counter = 1

    def add_state(self, s_current, s_choices, s_cost):
        self.states.loc[self.counter] = [s_current, s_choices, s_cost]
        self.counter += 1

    add_state("A", "B", 2)
    add_state("A", "C", 4)
    add_state("A", "D", 3)
    add_state("B", "E", 7)
    add_state("B", "F", 4)
    add_state("B", "G", 6)
    add_state("C", "E", 3)
    add_state("C", "F", 2)
    add_state("C", "G", 4)
    add_state("D", "E", 4)
    add_state("D", "F", 1)
    add_state("D", "G", 5)
    add_state("E", "H", 1)
    add_state("E", "I", 4)
    add_state("F", "H", 6)
    add_state("F", "I", 3)
    add_state("G", "H", 3)
    add_state("G", "I", 3)
    add_state("H", "J", 3)
    add_state("I", "J", 4)



    def choose(self,state):
        states_to_choose = self.states[self.states.Current == state]
        random_path = random.randint(0,len(states_to_choose))
        current_state = states_to_choose[random_path]


    def run(self):
        while self.current_state != self.home_state:
            print(self.states)
            self.choose(self.current_state)
            print(self.current_state)
            self.cost += 1



game = stagecoach()
game.run()

Answer 1

缺少的参数是第一个，通常称为self，当您在类的实例上调用方法时，它将自动传递。但是您并不是在一个实例上调用add_state()：您是作为一个普通函数调用它，并且必须传递所有四个参数。你不能这样做，因为你没有类的任何实例，因为你还在定义它。在

您需要编写一个__init__()方法，该方法执行add_state()调用以及当前类主体中的所有其他操作。这样，就会有一个实例调用add.state()！像这样：

def __init__(self):
    self.current_state = "A"
    self.home_state = "J"
    self.cost = 0

    self.index = range(1,20,1)
    self.columns = ["Current", "Choices", "Cost"]

    self.states = pd.DataFrame(columns=columns, index=index)

    self.counter = 1

    self.add_state("A", "B", 2)
    self.add_state("A", "C", 4)
    self.add_state("A", "D", 3)
    # and so on