Question

我需要一个二维列表来存储有关学生及其成绩的信息。

当我运行我的程序时，我只得到一个数字列表，但我需要为每个学生单独列出。任何人都可以帮助我吗？

这是我到目前为止所做的：

COLS= int(input("number of students to enter "))
ROWS= int(input("number of grades per student "))

def main():
    number =[]


    for c in range(COLS):
        student =(input("enter student ID number "))
        number.append(student)

        for r in range (ROWS):
            grades =(input("Enter grade for module: "))
            number.append(grades)

    print(number)

my result is 
number of students to enter 2
number of grades per student 4
enter student ID number 1234
Enter grade for module: 55
Enter grade for module: 66
Enter grade for module: 43
Enter grade for module: 33
enter student ID number 2345
Enter grade for module: 34
Enter grade for module: 56
Enter grade for module: 78
Enter grade for module: 99
['1234', '55', '66', '43', '33', '2345', '34', '56', '78', '99']
>>>

Answer 1

您需要为每一行创建新列表：

for c in range(COLS):
    grades = []
    student =(input("enter student ID number "))
    number.append(student)
    number.append(grades)

    for r in range (ROWS):
        grade =(input("Enter grade for module: "))
        grades.append(grade)

Answer 2

我会使用由学生ID索引的词典：

COLS= int(input("number of students to enter "))
ROWS= int(input("number of grades per student "))

def main():
    student_grades = {}

    for c in range(COLS):
        student =(input("enter student ID number "))
        grades = []

        for r in range (ROWS):
            grade =(input("Enter grade for module: "))
            grades.append(grade)
        student_grades[student] = grades

Answer 3

根据我的评论，使用list & dict comprehensions执行此操作的示例：

cols = int(input("Number of students: "))
rows = int(input("Number of grades per student: "))

grades = {input("Enter student ID number: "): 
             [input("Enter grade for module: ") for _ in range(rows)] 
          for _ in range(cols)}

请注意，这是Kyle Strand's answer中的字典，而不是列表。这样可以更好地适应数据，并且以后更容易使用它。

另外请注意，通过重复此操作可以实现更好的界面，直到用户决定不再输入更多学生，而不是直接询问将输入多少学生：

rows = int(input("Number of grades per student: "))

def get_students():
    while True:
        value = input("Enter student ID number, or nothing to finish: ")
        if not vale:
            return
        else:
            yield value

grades = {student: [input("Enter grade for module: ") for _ in range(rows)] 
          for student in get_students()}

这是通过一个生成器实现的，它生成从用户获得的新学号，直到用户不输入任何内容。

Answer 4

在将列表插入number列表之前，只需构建一个列表：

for c in range(COLS):
    student =(input("enter student ID number "))
    temp_arr = [student] # make a temporary array for the student id and their grades

    for r in range (ROWS):
        grades =(input("Enter grade for module: "))
        temp.append(grades) # append to the temp array here

    # after you are done getting the grades
    # insert the entire temp array into the number array
    number.append(temp)

此外，如果你创建了一个Student类，可能有一个id和一个grades列表，那么这些数据可能会以更好的方式存储。

Answer 5

我认为最好使用列表而不是二维列表 - 列表列表 - 因为它使得输入和访问的数据访问更容易和可读。出于同样的原因，我还将代码中的number更改为下面代码中的grades，以更好地反映其中的内容。

COLS = int(input("number of students: "))
ROWS = int(input("number of grades per student: "))

grades = {}

def main():
    for c in range(COLS):
        student = int(input("enter student ID: "))
        grades[student] = []  # initialize to empty row of grades

        for r in range(ROWS):
            grade = int(input("Enter grade for module: "))
            grades[student].append(grade)

    for student in grades.keys():
        print 'student:{}, grades:{}'.format(student, grades[student])

输入样本数据后的输出：

student:2345, grades:[34, 56, 78, 99]
student:1234, grades:[55, 66, 43, 33]

创建二维列表

5 个答案: