Question

我正在编写一个程序，允许用户输入学生记录，查看记录，删除记录和显示标记的平均值。我无法从列表中删除用户输入的名称以及学生标记。这是我到目前为止的代码

studentlist=[]
a=1
while a!=0:
    print ("""
1. Add new student records
2. Show all student records
3. Delete a student record
4. Dislay overall average coursework mark
5. Display overall average exam mark
6. Calculate average marks
0. Exit
Plese select an option
       """)
    a=int(input(""))
    if a==1:
        name=input("Enter a students name: ")
        cmark=int(input("Enter the students coursework mark: "))
        emark=int(input("Enter the students exam mark: "))
        student=(name,cmark,emark)
        print (student)
        studentlist.append(student)
        student=()
    if a==2:
        for n in studentlist:
            print ("Name:", n[0])
            print ("Courswork mark:",n[1])
            print ("Exam mark:", n[2])
            print ("")
    if a==3:
        name=input("Enter a students name: ")
        for n in studentlist:
            if n[0]==name:
                studentlist.remove(n[0])
                studentlist.remove(n[1])
                studentlist.remove(n[2])

Answer 1

您无法删除tuple的成员 - 您必须删除整个tuple。例如：

x = (1,2,3)
assert x[0] == 1 #yup, works.
x.remove(0) #AttributeError: 'tuple' object has no attribute 'remove'

tuple是不可变的，这意味着它们无法更改。正如上面的错误所解释的那样，tuple没有删除属性/方法（他们怎么可能？they are immutable）。

相反，请尝试从上面的代码示例中删除最后三行，并将其替换为下面的行，这将只删除整个tuple：

studentlist.remove(n)

如果您希望能够更改或删除个别成绩（或更正学生的姓名），建议您将学生信息存储在list或dict中（例如使用dict如下所示。

studentlist=[]
a=1
while a!=0:
    print ("""
1. Add new student records
2. Show all student records
3. Delete a student record
4. Dislay overall average coursework mark
5. Display overall average exam mark
6. Calculate average marks
0. Exit
Plese select an option
       """)
    a=int(input(""))
    if a==1:
        promptdict1 = {'name': 'Enter a students name: ', \
                       'cmark': 'Enter the students coursework mark: ', \
                       'emark': 'Enter the students exam mark: '}
        studentlist.append({'name': input(promptdict1['name']), \
                            'cmark': int(input(promptdict1['cmark'])), \
                            'emark': int(input(promptdict1['emark']))})
        print(studentlist[-1])
    if a==2:
        promptdict2 = {'name': 'Name:', \
                       'cmark': 'Courswork mark:', \
                       'emark': 'Exam mark:'}
        for student in studentlist:
            print(promptdict2['name'], student['name'])
            print(promptdict2['cmark'], student['cmark'])
            print(promptdict2['emark'], student['emark'], '\n')
    if a==3:
        name=input("Enter a students name: ")
        for n in studentlist:
            if n['name']==name:
                studentlist.remove(n)

Answer 2

用新列表覆盖旧列表可能更有意义

studentList = [item for item in studentList if item[0] != name]

如果你真的想删除它，你不应该在迭代它时修改列表...

for i,student in enumerate(studentList):
    if student[0] == name: 
       studentList.pop(i)
       break #STOP ITERATING NOW THAT WE CHANGED THE LIST

从列表中删除元组

2 个答案: