Python 为什么我的if语句得不到正确的答案？还有，如何找到所有输入的平均值？

由于某些原因，我在运行此程序时，没有得到正确数量的快速女性和快速男性。快的雌性是小于-19的数字，快的雄性是小于15的数字。另外，如果有人能建议如何找到所有输入组合的平均值

#Write a program that categorizes user input

#Ask for user input
userInput=input("Enter a time (negative for F, "" to quit): ")

#Initialize variables
female=0
male=0
noRunner=0
fastFemale=0
fastMale=0
count=0

#Categorize input into male, female, fast female, and fast male
while userInput!="":
    count=count+1
    if userInput=="0":
        userInput=noRunner
        noRunner=noRunner+1
    if str(userInput).startswith("-"):
        userInput=female
        female=female+1
        if float(userInput) >= 19.0 and float(userInput) < 0.0:
            userInput=fastFemale
            fastFemale=fastFemale+1
    elif float(userInput) > 0.0:
        male=count-female-noRunner
        if float(userInput) <= 15.0 and float(userInput) > 0.0:
            userInput=fastMale
            fastMale=fastMale+1
    userInput=input("Enter a time (negative for F, "" to quit): ")

#Computations
total=male+female
noShow=noRunner

#Print statements
print()
print("Try-Out Report")
print("-"*40)
print("Total number of runners:", count-noShow)
print("Number of runners who didn't show:", noShow)
print("female", female)
print("male", male)
print("Average time for male runners:")
print("Average time for female runners:")
print("Average time for all runners:")
print("Fast female runners:", fastFemale)
print("Fast male runners:", fastMale)

#编写一个程序，对用户输入进行分类
#请求用户输入
userInput=input（“输入时间（F为负数），“退出）：”）
#初始化变量
女性=0
男性=0
noRunner=0
fastFemale=0
fastMale=0
计数=0
#将输入分为男性、女性、快速女性和快速男性
而用户输入="":
计数=计数+1
如果userInput==“0”：
userInput=noRunner
noRunner=noRunner+1
如果str（userInput）.startswith（“-”）：
用户输入=女性
女=女+1
如果浮点（用户输入）>=19.0且浮点（用户输入）<0.0：
userInput=fastFemale
fastFemale=fastFemale+1
elif浮点（用户输入）>0.0：
男=女诺伦纳计数
如果浮动（用户输入）为0.0：
userInput=fastMale
fastMale=fastMale+1
userInput=input（“输入时间（F为负数），“退出）：”）
#计算
总数=男性+女性
noShow=noRunner
#打印报表
打印（）
打印（“试用报告”）
打印（“-”*40）
打印（“跑步者总数：”，无显示计数）
打印（“未显示的跑步者人数：”，无显示）
印刷品（“女性”，女性）
印刷品（“男性”，男性）
打印（“男性跑步者的平均时间：”）
打印（“女性跑步者的平均时间：”）
打印（“所有跑步者的平均时间：”）
打印（“快速女性跑步者：”，快速女性）
打印（“快速男跑步者：”，快速男）

当您获得输入时，构建一个总和，然后除以计数

当然，在初始化计数时初始化sum=0

由于您已经删除了“-”符号，因此不需要使用abs

sum += float(userval)

avg = sum/total

请注意，您应该使用如下代码

female += 1

而不是

female = female + 1

请注意，这里的问题是，在使用输入变量之前更改了它 这使得以后的所有检查都无效。在检查值之前，也不要使输入为正，这样它将始终为负，因此永远不会>19将其更改为字符串以查找“-”是错误的，只需检查<0即可

从已经是浮点或整数的userInput开始

检查负值，然后更改为abs（userval），以获取女性类别中的实际算术值

if str(userInput).startswith("-"):
    userInput=female # This messes up the next if
    female=female+1
    if float(userInput) >= 19.0 and float(userInput) < 0.0:
        userInput=fastFemale
        fastFemale=fastFemale+1

如果str（userInput）.startswith（“-”）：
userInput=female#这会把下一个
女=女+1
如果浮点（用户输入）>=19.0且浮点（用户输入）<0.0：
userInput=fastFemale
fastFemale=fastFemale+1

这让我大吃一惊。使用

userInput<0

，就像您在下面的

elif

上所做的那样

    ...
    userInput=female
    ...

当您这样做时，您只是丢失了userInput值

在交互式会话中玩

输入

，看看它是如何工作的。不需要

浮动（用户输入）

---

代码真的很糟糕。试着从问题的一个子集开始，例如只从女性开始，试着了解发生了什么，不要只是尝试随机地调整事情来获得结果。

你可以很好地利用pythons迭代器和列表函数（

sum

，

len

）和-comprehensions

大概是这样的：

def prompt():
    return input('Enter a time (negative for F, "" to quit): ')

data = [float(datum) for datum in iter(prompt, '')]

females = [-datum for datum in data if datum < 0.]
males = [datum for datum in data if datum > 0.]

print ('Males average: {}'.format(sum(males) / len(males)))
print ('Females average: {}'.format(sum(females) / len(females)))
print ('Fast males: {}'.format(sum(1 for male in males if male < 15.)))

---

要进一步分类，您可以执行以下操作：

fastMales = [male for male in males if male < 15.]
fastFemales = [female for female in females if female < 19.]

fastMales=[如果男性<15，则男性代表男性。]
fastFemales=[如果女性<19，则女性代表女性。]

我提取了一个Stats类，它只自动跟踪适用的值。它使您的代码稍微长一点，但更易于遵循：

import sys

if sys.hexversion < 0x3000000:
    inp = raw_input   # Python 2.x
else:
    inp = input       # Python 3.x

def average(sum, num):
    return sum / (num or 1.)    # prevent div-by-0

class Stats:
    def __init__(self, title, filter_fn, neg=False):
        self.filter_fn = filter_fn
        self.neg = neg
        self.num = 0
        self.sum = 0.

    def add(self, item):
        if self.filter_fn(item):
            self.num += 1
            self.sum += -item if self.neg else item

    @property
    def avg(self):
        return average(self.sum, self.num)

female =      Stats("Female runners",      lambda x: x < 0.       , True)
fast_female = Stats("Fast female runners", lambda x: -19. < x < 0., True)
no_show =     Stats("No shows",            lambda x: x == 0.            )
fast_male =   Stats("Fast male runners",   lambda x: 0. < x < 15.       )
male =        Stats("Male runners",        lambda x: 0. < x             )

def main():
    while True:
        s = inp("Enter run time (negative for female, blank to quit): ")
        try:
            time = float(s)
            for stat in [female, fast_female, no_show, fast_male, male]:
                stat.add(time)
        except ValueError:
            break

    print("\nTryout Report\n----------------------------------------")

    print(
        "All runners: {:d} male + {:d} female = {:d}  ({:d} no-shows)"
        .format(male.num, female.num, male.num + female.num, no_show.num)
    )
    print(
        "Average times: {:0.3f} male, {:0.3f} female, {:0.3f} overall"
        .format(male.avg, female.avg, average(male.sum + female.sum, male.num + female.num))
    )
    print(
        "Fast runners: {:d} male + {:d} female = {:d}"
        .format(fast_male.num, fast_female.num, fast_male.num + fast_female.num)
    )

if __name__=="__main__":
    main()

---

列出既大于19又小于0的数字。然后看看你的输入。还要注意python变量是区分大小写的。

fastMales = [male for male in males if male < 15.]
fastFemales = [female for female in females if female < 19.]

import sys

if sys.hexversion < 0x3000000:
    inp = raw_input   # Python 2.x
else:
    inp = input       # Python 3.x

def average(sum, num):
    return sum / (num or 1.)    # prevent div-by-0

class Stats:
    def __init__(self, title, filter_fn, neg=False):
        self.filter_fn = filter_fn
        self.neg = neg
        self.num = 0
        self.sum = 0.

    def add(self, item):
        if self.filter_fn(item):
            self.num += 1
            self.sum += -item if self.neg else item

    @property
    def avg(self):
        return average(self.sum, self.num)

female =      Stats("Female runners",      lambda x: x < 0.       , True)
fast_female = Stats("Fast female runners", lambda x: -19. < x < 0., True)
no_show =     Stats("No shows",            lambda x: x == 0.            )
fast_male =   Stats("Fast male runners",   lambda x: 0. < x < 15.       )
male =        Stats("Male runners",        lambda x: 0. < x             )

def main():
    while True:
        s = inp("Enter run time (negative for female, blank to quit): ")
        try:
            time = float(s)
            for stat in [female, fast_female, no_show, fast_male, male]:
                stat.add(time)
        except ValueError:
            break

    print("\nTryout Report\n----------------------------------------")

    print(
        "All runners: {:d} male + {:d} female = {:d}  ({:d} no-shows)"
        .format(male.num, female.num, male.num + female.num, no_show.num)
    )
    print(
        "Average times: {:0.3f} male, {:0.3f} female, {:0.3f} overall"
        .format(male.avg, female.avg, average(male.sum + female.sum, male.num + female.num))
    )
    print(
        "Fast runners: {:d} male + {:d} female = {:d}"
        .format(fast_male.num, fast_female.num, fast_male.num + fast_female.num)
    )

if __name__=="__main__":
    main()

Enter run time (negative for female, blank to quit): -20
Enter run time (negative for female, blank to quit): -16
Enter run time (negative for female, blank to quit): -12
Enter run time (negative for female, blank to quit): 0
Enter run time (negative for female, blank to quit): 0
Enter run time (negative for female, blank to quit): 12
Enter run time (negative for female, blank to quit): 14
Enter run time (negative for female, blank to quit): 16
Enter run time (negative for female, blank to quit): 

Tryout Report
----------------------------------------
All runners: 3 male + 3 female = 6  (2 no-shows)
Average times: 14.000 male, 16.000 female, 15.000 overall
Fast runners: 2 male + 2 female = 4