在这个 Python 作业问题上遇到麻烦

Question

问题：编写一个程序，不断地询问用户一个考试分数，该分数以 0 到 100 范围内的整数百分比形式给出。如果输入了除 -1 以外的范围之外的值，则打印出错误并提示用户再试一次。计算输入的所有有效成绩的平均值以及每个字母等级类别中的总成绩如下：90 到 100 是 A，80 到 89 是 B，70 到 79 是 C，60 到 69 是D，而 0 到 59 是 F。使用负分作为标记值来指示输入的结束。 （负值仅用于结束循环，所以不要在计算中使用它。）例如，如果输入是。

#Enter in the 4 exam scores
g1=int(input("Enter an exam score between 0 and 100 or -1 to end: "))
g2=int(input("Enter an exam score between 0 and 100 or -1 to end: "))
g3=int(input("Enter an exam score between 0 and 100 or -1 to end: "))
g4=int(input("Enter an exam score between 0 and 100 or -1 to end: "))

total =(g1 + g2 + g3 + g4)

while g1 is range(0,100):
    continue
else:
    print("Sorry",g1,"is not in the range of 0 and 100 or -1. Try again!")

while g2 is range(0,100):
    continue
else:
    print("Sorry",g2,"is not in the range of 0 and 100 or -1. Try again!")

while g3 is range(0,100):
    continue
else:
    print("Sorry",g3,"is not in the range of 0 and 100 or -1. Try again!")

while g4 is range(0,100):
    continue
else:
    print("Sorry",g4,"is not in the range of 0 and 100 or -1. Try again!")

#calculating Average
def calc_average(total):
    return total/4

def determine_letter_grade(grade):
    if 90 <= grade <= 100:
        1 + TotalA
    elif 80 <= grade <= 89:
        1 + TotalB
    elif 70 <= grade <= 79:
        1 + TotalC
    elif 60 <= grade <= 69:
        1 + TotalD
    else:
        1 + TotalF

grade=total
average=calc_average

#printing the average of the 4 scores
print("You entered four valid exam scores with an average of: " + str(average))
print("------------------------------------------------------------------------")
print("Grade Distribution:")
print("Number of A's: ",TotalA)
print("Number of B's: ",TotalB)
print("Number of C's: ",TotalC)
print("Number of D's: ",TotalD)
print("Number of F's: ",TotalF)

给我的示例输出：

Enter an exam score between 0 and 100 or -1 to end: 88.64 
Enter an exam score between 0 and 100 or -1 to end: 103
Sorry, 103 is not in the range of 0 and 100 or -1. Try Again! 
Enter an exam score between 0 and 100 or -1 to end: 99.10 
Enter an exam score between 0 and 100 or -1 to end: 71.52
Enter an exam score between 0 and 100 or -1 to end: 73
Enter an exam score between 0 and 100 or -1 to end: -1
You entered 4 valid exam scores with an average of 83.07.

Grade Distribution
Number of A’s = 1
Number of B’s = 1
Number of C’s = 2
Number of D’s = 0
Number of F’s = 0

注意：这是我的第一堂计算机科学课，所以我确信有一个明显的解决方法是我想念的，但我很感激我能得到的任何帮助

Answer 1

这是我的演练解释：

所以，程序应该询问用户他们得到了什么分数直到他们说他们得到了-1 的分数，然后你给他们他们的结果。要循环直到他们给出-1，我们可以使用while 循环：

inp = float(input("Enter an exam score between 0 and 100 or -1 to end: ")) # Get input
grades = []
while inp > -1: # Loop until user gives a score of -1
    if inp >= 0 and inp <= 100: # Check if valid grade
        grades.append(inp) # Add grade to grades list
        inp = float(input("Enter an exam score between 0 and 100 or -1 to end: ")) # Ask again
    else:
        print("Sorry", inp, "is not in the range of 0 and 100 or -1. Try again!") # Invalid grade

# ANALYSIS OF GRADES

# Format first line of output - the first str(len(grades)) give the amount of grades they entered,
# and the str(sum(grades) / len(grades)) gives the average of the grades list.
print("You entered", str(len(grades)), "valid exam scores with an average of", str(sum(grades) / len(grades)))

print("Grade Distribution:")
print("Number of A's =", str(sum(90 <= g <= 100 for g in grades)) # I am using a very short notation
print("Number of B's =", str(sum(80 <= g <= 89 for g in grades)) # here - this is basically counting
print("Number of C's =", str(sum(70 <= g <= 79 for g in grades)) # the number of grades that are
print("Number of D's =", str(sum(60 <= g <= 69 for g in grades)) # a valid value based on the checks
print("Number of F's =", str(sum(0 <= g <= 59 for g in grades)) # I am making.

希望我的 cmets 可以帮助您弄清楚我的代码中发生了什么！

Answer 2

这里你的问题可以分成几个部分，

1. 从用户那里获取考试数量
2. 从用户那里获得这些考试的有效输入
3. 计算所有考试的平均值
4. 计算成绩分布
5. 如果用户输入为-1则退出

以下代码遵循所有这些步骤

    #calculating Average
    def calc_average(scores):
            return sum(scores)/len(scores)



    grade_dist = {
    (90, 101):'A',
    (80,90):'B',
    (70, 80):'C',
    (59, 70):'D',
    (0,59):'F'
    }

    def get_grade_freq(scores):
        grades = {'A':0, 'B':0, 'C':0, 'D':0, 'F':0}

        for score in scores:
          for k, v in grade_dist.items():
            if score in range(k[0], k[1]):
              grades[v]+=1

        print("Grade distributions")

        for grade, number in grades.items():
            print("Number of {}’s = {}".format(grade, number))



    def get_scores(n):
        scores = []
        cond = True
        while cond and n>0:
          score = int(input("Enter an exam score between 0 and 100 or -1 to end : "))
          if score==-1:
            cond=False
            return -1
          if score not in range(0,101):
              print("Sorry, {} is not in the range of 0 and 100 or -1. Try Again!".format(score))
          if score in range(0,101):
            scores.append(score)
            n-=1
        return scores

    def main():
        n = int(input('total number of exams ' ))

        scores = get_scores(n)
        if scores == -1:
            exit(-1)

        average = calc_average(scores)

        print("You entered {} valid exam scores with an average of {}.".format(n, average))

        get_grade_freq(scores)


    if __name__=='__main__':
        main()

Answer 3

当您有多个类似事物的实例需要处理（得分范围、总计数）时，您必须尝试使用​​多值结构而不是单个变量。 Python 的列表和字典旨在收集多个条目作为位置列表或键控索引（字典）。

这将使您的代码更加通用。当您操纵概念而不是实例时，您就会知道自己走在了正确的轨道上。

例如：

grading = [(None,101),("A",90),("B",80),("C",70),("D",60),("F",0)]
scores  = {"A":0, "B":0, "C":0, "D":0, "F":0}
counts  = {"A":0, "B":0, "C":0, "D":0, "F":0}
while True:
    input_value = input("Enter an exam score between 0 and 100 or -1 to end: ")
    value       = int(input_value)
    if value == -1: break
    score = next((s for s,g  in grading if value >= g),None)
    if score is None:
        print("sorry ",input_value," is not -1 or in range of 0...100")
        continue
    scores[score] += value
    counts[score] += 1

inputCount = sum(counts.values())
average    = sum(scores.values())//max(1,inputCount)  
print("")
print("You entered", inputCount, "valid exam scores with an average of: ", average)
print("------------------------------------------------------------------------")
print("Grade Distribution:")
for grade,total in counts.items():
    print(f"Number of {grade}'s: ",total)

grading 列表包含成对的分数字母和最小值（以元组形式）。这样的结构将允许您通过查找值低于或等于输入值的第一个条目并使用相应的字母来将等级值转换为评分字母。

相同的列表用于验证输入值，方法是在 100 之后策略性地放置一个 None 值，并且没有低于零的值。 next() 函数将为您执行搜索并在不存在有效条目时返回 None。

您的主程序循环需要继续，直到输入值为 -1，但它至少需要遍历输入一次（典型的重复直到结构，但 Python 中只有 while）。所以while 语句将永远循环（即while True）并且需要在满足退出条件时任意中断。

要累积分数，字典 (scores) 比列表更适合，因为字典允许您使用键（分数字母）访问实例。这使您可以跟踪单个变量中的多个分数。计算每个分数的输入数也是如此。

要获得最后的平均值，您只需将 scores 字典的值分数相加，然后除以您添加到 counts 字典的分数计数。

最后要打印分数统计摘要，您可以再次利用字典结构，只需为所有分数字母和总数编写一个通用打印行。

Answer 4

这可能对你有用：

scores = {
    "A": 0,
    "B": 0,
    "C": 0,
    "D": 0,
    "F": 0,
}
total = 0
count = 0

input_value = 0

while (input_value != -1) and (count < 4):
    input_value = int(input("Enter an exam score between 0 and 100 or -1 to end: "))
    if 0 <= input_value <= 100:
        total += input_value
        count += 1
        if input_value >= 90:
            scores["A"] += 1
        elif input_value >= 80:
            scores["B"] += 1
        elif input_value >= 70:
            scores["C"] += 1
        elif input_value >= 60:
            scores["D"] += 1
        else:
            scores["F"] += 1
    else:
        print("Sorry", input_value, "is not in the range of 0 and 100 or -1. Try again!")

print("You entered {} valid exam scores with an average of: {}".format(count, total / count))
print("------------------------------------------------------------------------")
print("Grade Distribution:")
print("Number of A's: ", scores['A'])
print("Number of B's: ", scores['B'])
print("Number of C's: ", scores['C'])
print("Number of D's: ", scores['D'])
print("Number of F's: ", scores['F'])