Question

我正在做一个Python类介绍的项目，我必须创建一个成绩册。在这本成绩簿中，我需要显示每个成绩字母值的学生数量并将其写入文件。一切正常，它不会破坏或任何东西，但在显示时，它看起来像这样：

(1, " students got A's")
(2, " students got B's")
(3, " students got C's")
(4, " students got D's")
(5, ' students failed')

当我希望它看起来像这样：

1 students got A's
2 students got B's
...and so on

我该如何解决这个问题？我可以把它原样转过来，但我宁愿输出看起来也不错。完整代码供参考：

#1 Open file
WriteTo=open("ClassNameGrades.txt", "w")

#2 Initialize variables
MoreStudents="Yes"
A=0
B=0
C=0
D=0
F=0

#3 Inputs and writing
ClassName=input("What is the class called? ") + '\n'
TeacherName=input("What is the teacher's name? ") + '\n'
WriteTo.write(ClassName)
WriteTo.write(TeacherName)

#4 Loop student inputs
while MoreStudents=='Yes':
    Name=input("What is the student's name? ")
    Grade=input("What is the student's grade number? ")
    WriteName=str(Name)
    SpaceName = ": "
    IntGrade=int(Grade)
    WriteGrade=Grade + '\n'
    WriteTo.write(WriteName)
    WriteTo.write(SpaceName)
    WriteTo.write(WriteGrade)
    #5 Assigning letter to grade
    if IntGrade>=90:
        A=A+1
    elif IntGrade>=80:
        B=B+1
    elif IntGrade>=70:
        C=C+1
    elif IntGrade>=60:
        D=D+1
    else:
        F=F+1
    MoreStudents=input("Are there any more students? 'Yes' or 'No'")


#6 Assigning what to write in the file
PrintA=A," students got A's"
PrintB=B," students got B's"
PrintC=C," students got C's"
PrintD=D," students got D's"
PrintF=F," students failed"

#7 Writing to file
WriteTo.write(str(PrintA))
WriteTo.write("\n")
WriteTo.write(str(PrintB))
WriteTo.write("\n")
WriteTo.write(str(PrintC))
WriteTo.write("\n")
WriteTo.write(str(PrintD))
WriteTo.write("\n")
WriteTo.write(str(PrintF))

#8 Display in program
print(ClassName)
print(TeacherName)
print(PrintA)
print(PrintB)
print(PrintC)
print(PrintD)
print(PrintF)

Answer 1

执行此操作时：

PrintA=A," students got A's"

...创建一个包含两个值的元组。

当您在这样的元组上调用str时：

WriteTo.write(str(PrintA))

你得到的是括号中的两个值，正如你所看到的那样。

如果你想以某种特定的方式格式化结果，你必须明确地这样做，而不是制作一个元组：

PrintA = f"{A} students got A's"
# ...
WriteTo.write(PrintA)

...或者不只是在元组上调用str：

WriteTo.write(f"{PrintA[0]} {PrintA[1]}")

对于您的情况，第一个版本可能更具可读性，但在某些现实应用中，可能有理由更喜欢第二个版本。

“f-string”格式化需要Python 3.6。如果您使用的是3.5或2.7，则可以使用str.format代替：

PrintA="{} students got A's".format(A)

...如果您发现format难以理解，您可以直接使用字符串方法：

PrintA = str(A) + " students got A's"

Answer 2

假设你已经得到了这个结果：

(1, " students got A's")
(2, " students got B's")
(3, " students got C's")
(4, " students got D's")
(5, ' students failed')

对于其中的每一个，您只需将第一个元素更改为字符串并将它们连接在一起。

def helper(in): 
    return str(in[0]) + in[1]
helper((5, ' students failed'))
>>>"5 students failed"

只需将函数放在代码中并使用它修改要打印的每个内容：

WriteTo.write(helper(PrintA))

Answer 3

如下的行：

PrintA=A," students got A's"
PrintB=B," students got B's"
PrintC=C," students got C's"
PrintD=D," students got D's"
PrintF=F," students failed"

实际上定义了tuples，当打印出tuple时，它首先转换为str，这使它看起来像(x, y)，因此它会打印出来：

(1, " students got A's")

相反，您要做的是直接创建str，如下所示：

PrintA=str(A) + " students got A's"
PrintB=str(B) + " students got B's"
PrintC=str(C) + " students got C's"
PrintD=str(D) + " students got D's"
PrintF=str(F) + " students failed"

因此，当它打印出来时（作为str），它会像：

1, students got A's

以书面形式格式化为文件

3 个答案: