python-3.x 变量未定义错误时,它是明确定义的?

hjzp0vay  于 2023-07-01  发布在  Python
关注(0)|答案(1)|浏览(141)
def standardCalBurn(weight, height, age):
    calories_needed = 655 + (4.3 * weight) + (4.7 * height) - (4.7 * age)
    print(f"{calories_needed:.1f} calories are needed per day to sustain weight of {weight}")

def burnedRunning(weight):
    calories_burned_per_minute = weight * 0.095
    return calories_burned_per_minute

def burnedWalking(weight):
    calories_burned_per_minute = weight * 0.054
    return calories_burned_per_minute

def burnedJogging(weight):
    calories_burned_per_minute = weight * 0.0775
    return calories_burned_per_minute

weight = float(input("Please enter your weight: "))
height = float(input("Please enter your height (in inches): "))
age = float(input("Please enter your age: "))

standardCalBurn(weight, height, age)

calories_to_burn = float(input("How many calories do you wish to burn while exercising? "))

activity = ""

while activity in ["WALK", "RUN", "JOG"]:
    if activity == "WALK":
        calories_burned_per_minute = burnedWalking(weight)
    if activity == "RUN":
        calories_burned_per_minute = burnedRunning(weight)
    if activity == "JOG":
        calories_burned_per_minute = burnedJogging(weight)
    if activity not in ["WALK", "JOG", "RUN"]:
        activity = input("Invalid input. Will you WALK, RUN, or JOG? ").upper()

minutes_to_burn = calories_to_burn / calories_burned_per_minute

print(f"You will burn {calories_burned_per_minute:.2f} calories per minute")
print(f"You will need to {activity} for {minutes_to_burn:.2f} minutes")

每当我尝试运行我的代码时,它说calories_burned_per_minute是未定义的,而我之前已经明确定义了。任何帮助都很感激。谢谢你。
追溯(最近一次调用):文件“",第37行,在NameError中:未定义名称“calories_burned_per_minute”

0s7z1bwu

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引发NameError不是bug,这是正确的行为,因为calories_burned_per_minute确实是未定义的。
为什么?因为你的循环没有运行。''不是["WALK", "RUN", "JOG"]的成员。所以activity in ["WALK", "RUN", "JOG"]是false。
您的while循环没有运行,因为while循环只在满足条件时运行,并在不再满足条件时停止。在这里,你的条件永远不会满足。
试试这个:

while False:
    print(True)

发生了什么?完全没有。
while activity in ["WALK", "RUN", "JOG"]更改为while activity not in ["WALK", "RUN", "JOG"]
那么你获取输入的逻辑是完全错误的。
你应该这样做:

while activity not in ["WALK", "RUN", "JOG"]:
    activity = input("Invalid input. Will you WALK, RUN, or JOG? ").upper()

然后这个:

functions = {'WALK': burnedWalking, 'RUN': burnedRunning, 'JOG': burnedJogging}
calories_burned_per_minute  = functions[activity](weight)

使用matchcase

match activity:
    case 'WALK':
        func = burnedWalking
    case 'RUN':
        func = burnedRunning
    case 'JOG':
        func = burnedJogging
calories_burned_per_minute  = func(weight)

你有三个函数,只有一个值是不同的,这是不好的,只是使用一个函数,并通过第二个值作为参数。你的函数名也不遵循Python命名约定,你的变量名也太长了,你没有内联立即返回的变量,你在函数内部使用print,你使用input函数而不是接受参数,你没有做类型提示......
我已经重构了你的代码,并删除了所有的cruft:

from enum import Enum

class Activity(Enum):
    Run = 0.095
    Jog = 0.0775
    Walk = 0.054

def standard_burn(weight: int | float, height: int | float, age: int | float) -> float:
    return 655 + (4.3 * weight) + (4.7 * height) - (4.7 * age)

def burn(weight: int | float, act: Activity):
    return weight * act.value

def calc_calories(
    weight: int | float,
    height: int | float,
    age: int | float,
    target: int | float,
    act: Activity,
) -> None:
    burn_rate = burn(weight, act)
    duration = target / burn_rate
    print(f"You will burn {burn_rate:.2f} calories per minute")
    print(f"You will need to {act} for {duration:.2f} minutes")
    print(
        f"{standard_burn(weight, height, age):.1f} calories are needed per day to sustain weight of {weight}"
    )

像这样使用:

In [12]: calc_calories(1, 1, 1, 1, Activity.Walk)
You will burn 0.05 calories per minute
You will need to Activity.Walk for 18.52 minutes
659.3 calories are needed per day to sustain weight of 1

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