Python 3.11.1行星体重转换器：输入特定行星名输出对应结果的问题

我是编程新手，正在用Python 3.11.1写一个基于行星重力系数的体重转换器。需求是用户输入体重和行星名后，输出对应行星上的体重，但现有代码有问题：用for循环会输出所有行星的转换结果；换while或if判断又会触发“无效选项”提示，试了各种方法都没解决，求帮忙。

原代码 #

planets = ['Mercury', 'Venus', 'Earth', 'Moon', 'Mars', 'Jupiter', 'Saturn', 'Uranus', 'Neptune', 'Pluto']
factors = ['0.4155', '0.8975', '1.000', '0.166', '0.3507', '2.5374', '1.0677', '0.8947', '1.1794', '0.0899']
planets_factors = dict(zip(planets, factors))


class WeightConvertor:
    def __init__(self):
        self.user_weight = user_weight
        self.planet = planet

    def __str__(self):
        return f"user_weight = {self.user_weight} planet = {self.planet}"

    def convertor():
        print("This choice allows you to see your weight on another planet.")
        print()
        print(planets)
        user_choice = input("Please choose a planet from the list above: ").upper()
        user_weight = float(input("Please enter your weight here: "))
        print()
        print()
        planet_choice = []
        for user_choice in planets:
            if user_choice == "Mercury":
                print("You chose Mercury.")
                converted_mercury = user_weight * 0.4155
                print()
                print("Your weight on", user_choice, "is", converted_mercury)
                print()
            elif user_choice == "Venus":
                print("You chose Venus.")
                converted_venus = user_weight * 0.8975
                print()
                print("Your weight on", user_choice, "is", converted_venus)
                print()
            elif user_choice == "Earth":
                print("You chose Earth.")
                converted_earth = user_weight * 1.000
                print()
                print("Your weight on", user_choice, "is", converted_earth)
                print()
            elif user_choice == "Moon":
                print("You chose Moon.")
                converted_moon = user_weight * 0.166
                print()
                print("Your weight on", user_choice, "is", converted_moon)
                print()
            elif user_choice == "Mars":
                print("You chose Mars.")
                converted_mars = user_weight * 0.3507
                print()
                print("Your weight on", user_choice, "is", converted_mars)
                print()
            elif user_choice == "Jupiter":
                print("You chose Jupiter.")
                converted_jupiter = user_weight * 2.5374
                print()
                print("Your weight on", user_choice, "is", converted_jupiter)
                print()
            elif user_choice == "Saturn":
                print("You chose Saturn.")
                converted_saturn = user_weight * 1.0677
                print()
                print("Your weight on", user_choice, "is", converted_saturn)
                print()
            elif user_choice == "Uranus":
                print("You chose Uranus.")
                converted_uranus = user_weight * 0.8947
                print()
                print("Your weight on", user_choice, "is", converted_uranus)
                print()
            elif user_choice == "Neptune":
                print("You chose Neptune.")
                converted_neptune = user_weight * 1.1794
                print()
                print("Your weight on", user_choice, "is", converted_neptune)
                print()
            elif user_choice == "Pluto":
                print("You chose Pluto.")
                converted_pluto = user_weight * 0.0899
                print()
                print("Your weight on", user_choice, "is", converted_pluto)
                print()
        else:
            print("Invalid Option")
            print("Please Try Again")
            print()
            user_choice = input("Please choose a planet from the list: ")

WeightConvertor.convertor()

问题分析 #

• 用户输入的user_choice被转成大写，但后续判断用的是行星原名字符串（如"Mercury"），大小写不匹配导致判断失效
• 没必要遍历所有行星，应该直接用用户输入的选项匹配
• 已经创建的planets_factors字典未被使用，反而写了大量重复的elif判断，冗余且易出错
• convertor方法是类方法但未加@classmethod装饰器，类的__init__方法直接使用未定义的变量，逻辑混乱
• for循环的else分支仅在循环正常结束时执行，不是有效的无效输入判断逻辑

修改后的代码 #

planets = ['Mercury', 'Venus', 'Earth', 'Moon', 'Mars', 'Jupiter', 'Saturn', 'Uranus', 'Neptune', 'Pluto']
# 将系数转为浮点数，方便计算
factors = [0.4155, 0.8975, 1.000, 0.166, 0.3507, 2.5374, 1.0677, 0.8947, 1.1794, 0.0899]
planets_factors = dict(zip(planets, factors))


class WeightConverter:
    @classmethod
    def convert(cls):
        print("这个工具可以帮你计算在其他行星上的体重。")
        print()
        print("可选行星：", ", ".join(planets))
        
        # 循环获取有效输入，直到用户输入正确的行星
        while True:
            user_choice = input("请选择上述列表中的行星：").strip().capitalize()
            if user_choice in planets_factors:
                break
            print("无效选项，请重新输入！")
        
        user_weight = float(input("请输入你的体重："))
        print()
        
        # 直接从字典获取重力系数
        gravity_factor = planets_factors[user_choice]
        converted_weight = user_weight * gravity_factor
        
        print(f"你选择了{user_choice}。")
        print(f"你在{user_choice}上的体重是{converted_weight:.2f}")


WeightConverter.convert()

关键修改点 #

• 把factors转为浮点数，避免字符串转浮点的额外操作
• 使用@classmethod装饰器规范类方法定义
• 用while循环做输入验证，确保用户输入的行星在有效列表内
• 利用planets_factors字典直接获取系数，删除冗余的elif判断
• 对用户输入做大小写统一处理（capitalize()），解决大小写不匹配问题
• 输出结果保留两位小数，提升可读性

内容的提问来源于stack exchange，提问作者Cloud