在 Python 中计算参数、参数、将变量传递给函数时遇到问题

Question

我从概念上理解这一点，但我似乎无法理解语法。这是我正在做的具体工作——从 5 个输入中获得平均评分，并显示与平均评分相关的星星数量

def main():
    score = float(input("Enter a score between 0 and 10: "))

    while score < 0 or score > 10:
        score = float(input("ERROR! Enter a score between 0 and 10: "))
    else:
        for num in range(1,5):
            score = float(input("Enter a score between 0 and 10: "))
            avg = score / 5
        stars = determine_stars()
        print(f'Your score of {avg} gives you {stars}')
        
def determine_stars():
    if avg >= 9.0 or avg <= 10.0:
        stars = "*****"
    elif avg >= 8.0 or avg <= 8.9:
        stars = "****"
    elif avg >= 7.0 or avg <= 7.9:
        stars = "***"
    elif avg >= 6.0 or avg <= 6.9:
        stars = "**"
    elif avg >= 5.0 or avg <= 5.9:
        stars = "*"
    else:
        stars = "No Stars"

main()

Answer 1

这里发生了一些您可能需要更改的事情。

1. determine_stars 是一个独立于 main 的函数（至少是目前的写法）。因为它是一个不同的函数，所以它不会将

   avg

   识别为函数内部的变量（查看全局变量以了解原因）。这里最简单的解决方案是提供 avg 作为该函数的输入。像这样：

def main():
    score = float(input("Enter a score between 0 and 10: "))

    while score < 0 or score > 10:
        score = float(input("ERROR! Enter a score between 0 and 10: "))
    else:
        for num in range(1,5):
            score = float(input("Enter a score between 0 and 10: "))
            avg = score / 5
        stars = determine_stars(avg)
        print(f'Your score of {avg} gives you {stars}')
    
def determine_stars(avg):
    if avg >= 9.0 or avg <= 10.0:
        stars = "*****"
    elif avg >= 8.0 or avg <= 8.9:
        stars = "****"
    elif avg >= 7.0 or avg <= 7.9:
        stars = "***"
    elif avg >= 6.0 or avg <= 6.9:
        stars = "**"
    elif avg >= 5.0 or avg <= 5.9:
        stars = "*"
    else:
        stars = "No Stars"

main()

2. 这是第一步。您需要做的第二件事是计算 5 个分数的平均值。假设这是你需要做的，我会稍微改变一下 else 语句：

else:
    score = 0
    for num in range(1,5):
        score += float(input("Enter a score between 0 and 10: "))
    avg = score/5

Answer 2

您的代码中存在许多问题。即使您修复了缩进错误，您也有未声明的变量，以及数学和条件问题。下面是一个完整的注释示例，它简化了整个过程。

from statistics import mean
  
#constant expression
SCMSG = "Enter a score between 0 and 10: "
SCORE = lambda: float(input(SCMSG))

#configure
MIN   = 0
MAX   = 10
AVGS  = 5
HALF  = MAX//2


def main():
    scores = []
    
    #input loop
    for _ in range(AVGS):
        #keep asking for the same input until it is correct
        while MIN > (s:=SCORE()) or s > MAX: pass
            
        #must be correct, append to scores
        scores.append(s)
    
    #loop is finished - get average
    avg   = mean(scores)
    
    #determine stars (0 to 5) - no branches
    stars = "*"*int(min(max(MIN,avg-HALF+1),HALF)) or 'no stars'
    
    #print data
    print(f'Your score of {avg} gives you {stars}')
      
      
main()

测试所有可能的星级结果

for i in range(MAX*100+1):
    print(f'average: {(avg:=(i*.01)):.2f}', 
          "*"*int(min(max(MIN,avg-HALF+1),HALF)) or 'no stars')

Answer 3

几件事，你的

determine_stars()

函数需要返回一些它目前没有的东西。它还需要将您的

avg

作为参数。我添加了

return stars

，这正是您要找的。其次，您必须将“或”调整为“和”，因为您要同时满足这两个条件，而不仅仅是一个或另一个。

对于您的主要功能，您打算收集 5 个介于 0-10 之间的值输入，如果抛出您不希望出现的错误，则要求提供有效输入。您可以通过首先创建一个 for 循环集来运行 5 次来实现这一点。然后是一个 while 循环，除非插入有效输入，否则不会中断，一旦收到有效输入，脚本就会继续。

我还使用总分值来满足 while 循环的条件，因为分数已经设置并且您不想更改它。

def main():
    total_score = 0
    for _ in range(5):
        score = None
        while score is None or not (0 <= score <= 10):
            try:
                score = float(input("Enter a score between 0 and 10: "))
                if not (0 <= score <= 10):
                    raise ValueError
            except ValueError:
                print("Error: Enter a valid score between 0 and 10")

        total_score += score

    avg = total_score / 5
    print(f'Your score of {avg} gives you {determine_stars(avg)}')



def determine_stars(avg):
    if avg >= 9.0 and avg <= 10.0:
        stars = "*****"
    elif avg >= 8.0 and avg <= 8.9:
        stars = "****"
    elif avg >= 7.0 and avg <= 7.9:
        stars = "***"
    elif avg >= 6.0 and avg <= 6.9:
        stars = "**"
    elif avg >= 5.0 and avg <= 5.9:
        stars = "*"
    else:
        stars = "No Stars"
    return stars

main()

Answer 4

识别错误

determine_stars()

功能有几个问题：

1. avg

   的范围：它是一个独立于

   main()

   的函数，因此不会识别

   avg

   函数中定义的变量

   main()

   。也就是说，

   avg

   不在

   determine_stars()

   的范围内。

   相反，它应该有自己的参数代表这个值。

2. 离散范围：

   float

   的值本质上是连续的，因此它的小数部分可以有尽可能多的数字。因此，使用离散范围会丢失，例如，

   8.9

   和

   9.0

   之间的值（例如

   8.951

   ）。

   相反，保持范围连续。

3. 无输出：不要忘记使用

   determine_stars()

   语句指定

   return

   函数的输出值。

4. If条件：

   if

   语句的条件应该使用

   and

   ，而不是

   or

   。否则他们每个人都是

   True

   ，结果总是五颗星。

还有

main()

功能：

1. Validation：

   while

   循环应该在

   for

   循环内，以跟踪every用户输入。

2. 计算平均值：

   avg

   变量定义不明确。需要有一个可以累积分数的变量，作为所有分数的总和。然后可以将这个值除以得到平均值。

3. For循环范围：

   range(i, j)

   函数迭代区间

   [i, j)

   中的数字（它是独占的）。因此

   range(1, 5)

   只会进行

   4

   迭代而不是

   5

   。而是写

   range(0, 5)

   （或简单地

   range(5)

   ）。

固定代码和注解

我已经编辑了您的代码并修复了这些问题。为了帮助您理解语法，我还添加了注释。

# Outputs the star average from a given value.
def determine_stars(avg):
    # Five stars: 9 <= avg <= 10
    if avg >= 9 and avg <= 10:
        stars = "*****"
        
    # Four stars: 8 <= avg < 9
    elif avg >= 8 and avg < 9:
        stars = "****"
        
    # Three stars: 7 <= avg < 8
    elif avg >= 7 and avg < 8:
        stars = "***"
        
    # Two stars: 6 <= avg < 7
    elif avg >= 6 and avg < 7:
        stars = "**"
        
    # One star: 5 <= avg < 6
    elif avg >= 5 and avg < 6:
        stars = "*"
        
    # Otherwise, no stars.
    else:
        stars = "No Stars"
    
    # Have the function produce the value of stars as its output
    return stars

# Main program execution
def main():
    
    # To store the sum of the user's scores.
    total = 0

    # Do 5 loops, to take 5 scores from the user.
    for num in range(0, 5):
        # Ask the user to input a score between 0 and 10. Convert their input to a float (i.e. a decimal).
        score = float(input("Enter a score between 0 and 10: "))

        # Validation: Keep rejecting their input until it is in the valid range (0 to 10).
        while score < 0 or score > 10:
            score = float(input("ERROR! Enter a score between 0 and 10: "))
        
        # Add the score to the total.
        total += score
    
    # Calculate the average score by dividing the total from the number of scores (5).
    avg = total / 5
    
    # Determine the star rating.
    stars = determine_stars(avg)
    
    # Output the star rating.
    print(f'Your score of {avg} gives you {stars}')