从用户输入的列表中删除名称，并平均成绩

Question

我已经阅读了很多关于Python的教程，并且目前正在使用python进行编程类的入门，但是我无法弄清楚。 我已经搜索了堆栈溢出，dani网站，java2s，github和许多其他内容，但无法理解我在做什么错。

这是我编程班上的最后一个项目，我想在课堂上做几件事，然后将它们导入主程序。

最终，我希望也可以在我的工作场所中使用它，并希望它向用户提供选项菜单。 1：添加名称和键入速度。 2：按值删除姓名（学生的姓名，如果可能的话，我想在课堂上做这件事。3：打印姓名和速度。4：打印速度列表。5：打印平均值速度列表中的速度（我也想在课堂上做），并退出程序6。

我试图变得雄心勃勃，并创建了一个随机的名称生成器，所以我也创建了一个打印名称列表的函数，但这要在星期一早上进行，所以由于没有时间，我取消了该项目。

无效的部分是＃2-删除名称和＃3-平均分数。 在＃2上，我没有尝试过.remove，del或其他任何我见过的人尝试过的事情。 似乎大多数示例仅是硬编码的。其他示例对我而言没有意义。 在＃3上，我尝试了多种计算，包括将数字分别加在一起，创建不同的函数并除以len，还尝试了均值Built_in。

我可以根据工作情况进行分配，但是其他部分对将其用于特定目的特别有用。

这是我的课程：

class student_info:

    def __init__(self):
        self.name = ""
        self.speed = ""
        self.speed_average = 0

def speed_average(self):
    return sum(self.speed) / len(self.speed)

和主程序（带注释）：

import studentClass

name_list = []
speed = 0

def edit_list(name):
    new_name = input("What is the student's name? ")
    if new_name != "":
        name.name = new_name

    while True:
        try:
            typing_speed = input("What was the last typing speed? ")
            if speed != "":
                name.speed = float(typing_speed)
                #print (test_score)
            else:
                raise ValueError
            break
        except ValueError:
            print("Not a valid score.")

def print_students(list):
    for i, n in enumerate(list):
        print("#%d: Name: %s, Typing Speed (wpm): %d" % (i+1, n.name, n.speed))

def print_speed(list):
    for i, n in enumerate(list):
        print("%s" % (n.speed))

##Since the class instantiation didn't work, I tried creating a function - that didn't work either.
def print_avg(list):
    speed_list = speed
    print(sum(speed)/len(speed))

while True:
    print("Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit")
    choice = input(" >> ")
    if choice == '1':
        name_list.append(studentClass.student_info())
        edit_list(name_list[-1])
    elif choice == '2':
        names = [name_list]       
        del_name = input("What name would you like to remove? ")
        name_list.remove(del_name)
        if del_name not in name_list:
            print("Name not found.")
        else:
            print("%s removed." % del_name)
    elif choice == '3':
        print_students(name_list)           
    elif choice == '4':
        print_speed(name_list)
    elif choice == '5':
        class_avg = studentClass.student_info()
        print("Average score for class: " %(class_avg.speed_average))
    elif choice == '6':
        print('Happy Typing!')
        break
    else:
        print("That's not an option. Please try again.")



Error returned when #2 is selected:
Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
 >> 1
What is the student's name? john
What was the last typing speed? 20
Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
 >> 1
What is the student's name? mary
What was the last typing speed? 10
Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
 >> 4
20.0
10.0
Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
 >> 3
#1: Name: john, Typing Speed (wpm): 20
#2: Name: mary, Typing Speed (wpm): 10
Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
 >> 2
What name would you like to remove? john
Traceback (most recent call last):
  File "C:\Users\Whited\Desktop\Classes\Programming\studentRun.py", line 44, in <module>
    name_list.remove(del_name)
ValueError: list.remove(x): x not in list
>>>



Error returned when #5 is selected:

    Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
     >> 1
    What is the student's name? john
    What was the last typing speed? 20
    Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
     >> 1
    What is the student's name? mary
    What was the last typing speed? 10
    Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit
     >> 5
    Traceback (most recent call last):
      File "C:\Users\Whited\Desktop\Classes\Programming\studentRun.py", line 56, in <module>
        print("Average score for class: " %(class_avg.speed_average))
    TypeError: not all arguments converted during string formatting
    >>> 

其他一切都按预期运行。 如果有人可以帮助我解决这个问题，我将不胜感激。 谢谢！

更新：以适当的缩进和调用来运行5。

追溯（最近一次通话）：文件“ C：\\ Users \\ Whited \\ Desktop \\ Classes \\ Programming \\ studentRun.py”，行56，在打印中（“类的平均分数：“％（class_avg.speed_average（））） TypeError：“ int”对象不可调用

更新：顺便使用Python 3。 -并且，该文件另存为studentClass

Answer 1

我很无聊，而且有点嗡嗡作响，所以我想我只想抛出一些可以从中学习的工作代码：

# A Student object will just take care of tracking the name and speed.
# Classes like this in Python (with no methods) are often better represented
# by a namedtuple from the collections package.
class Student(object):

    def __init__(self, name="", speed=0):
        self.name = name
        self.speed = speed

# The Class object will represent a group of students.
# The students are tracked via a dictionary where the key is the name of 
# the student and the value is the Student object.
class Class(object):

    def __init__(self):
        """ Create an empty dictionary for the students """
        self.students = {}

    def add_student(self, student):
        """ Add a student to the "roster".  The student name will be the 
            key and the Student instance will be the value """
        self.students[student.name] = student

    def remove_student(self, name):
        """ Remove a student if they exist.  If they exist and are removed
            return True.  If they do not exist, return False """
        if name in self.students:
            del self.students[name]
            return True
        return False

    def average(self):
        """ Get the average speed of the students.
            The self.student.values() will be the values of the self.students
            dictionary, which means it will be a list of students.
            For each of the students, get their speed.  Sum those speeds
            and divide by the number of students.
            The fancy syntax of [x for x in y] below is called a list comprehension """
        return sum(student.speed for student in self.students.values()) / len(self.students)

def print_students(group):
    for i, student in enumerate(group.students.values()):
        print("#%d: Name: %s, Typing Speed (wpm): %d" % (i+1, student.name, student.speed))

def print_speed(group):
    for i, student in enumerate(group.students.values()):
        print("#%d: Typing Speed (wpm): %d" % (i+1, student.speed))


def add_student(group):
    new_name = ""
    typing_speed = None
    while not new_name:
        new_name = input("What is the student's name? ")
    while typing_speed in ("", None):
        typing_speed = input("What was the last typing speed? ")
        try:
            typing_speed = float(typing_speed)
        except:
            print("Please enter a number")
            typing_speed = None
            continue
    # We have a valid name and value speed, so create a Student and add them to the Class
    group.add_student(Student(new_name, typing_speed))


if __name__ == "__main__":
    group = Class()

    while True:
        print("Hi user, (1) add (2) delete (3) print (4) print scores (5) print average (6) quit")
        choice = input(" >> ")

        if choice == '1':
            add_student(group)
            continue

        if choice == '2':
            del_name = input("What name would you like to remove? ")
            if group.remove_student(del_name):
                print("%s removed." % del_name)
            else:
                print("Name not found.")
            continue

        if choice == '3':
            print_students(group)
            continue

        if choice == '4':
            print_speed(group)
            continue

        if choice == '5':
            print("Average score for class: %0.2f" %(group.average()))
            continue

        if choice == '6':
            print('Happy Typing!')
            break

        print("That's not an option. Please try again.")

我更喜欢if =>在这种情况下继续，而不是if，elif ...

使用班级（粗略地命名）来管理学生（添加和删除）并取其平均值是一种很好的方法。

至于你做错了什么：

1. 删除学生。

您的name_list不是名称列表，它是student_info的列表。 您尝试先从列表中remove该名称，然后再检查该名称是否在其中，因此这将始终失败。 至少您要在调用remove之前检查是否存在。 但这对您永远不会起作用，因为列表不包含字符串，而是包含student_info 。 要使您的工作正常，您需要做类似的事情

found = False
for i, student in enumerate(name_list):
    if student.name == del_name:
        found = i
if found != False:
    del name_list[found]
    print("Deleted...")
else:
    print("Could not find name %s" % (del_name,))

2. 取平均值：

您正在做的是创建一个Student_info的新的空实例。 您要做的就是获取现有学生的价值。

total_score = 0
for student in name_list:
    total_score += student.speed
average = total_score / len(name_list)

在评论中回答您的问题：

1. 所有类都应从对象继承（新样式类） https://wiki.python.org/moin/NewClassVsClassicClass

2. values是一种获取字典值的方法。

   {"1": ['a', 'b'], "foo", 10.0}.values() == [["a", "b"], 10.0]

3. 只需将Student和Class类复制到另一个文件（例如，使用models.py），然后执行以下任一操作：

   import models

然后，在任何使用“学生”或“班级”（在models.py之外）的地方，都使用模型作为前缀。 喜欢

group = models.Class()
...
group.append(models.Student(new_name, typing_speed))

或者你可能只有

from models import *

这会将所有内容从models.py导入当前名称空间，因此无需更改其他代码。 保留名称空间是一个好主意...所以我会选择选项1。

4. 名称==主要内容...

if __name__ == "__main__"

最好在每个文件中都包含此内容。 执行python程序时，执行的文件名为 “ main ”。 此检查将告诉您是否正在执行文件。 如果您的文件是通过其他方式导入的，则名称将不是“ main ”。 这使您可以根据执行还是导入来执行不同的操作。

Answer 2

我认为您本可以使用字典来解决这个问题。

另外，您还有一个成员speed_average和一个成员函数speed_average。 函数和变量的名称不同。