Python：TypeError：“ float”对象不可下标

Question

def get_data(fp):
    data = []
    for line in fp:
        line_list_ints = [int(number) for number in line.split()]
        data.append(line_list_ints)
    return data

def calculate_grades(data):
    for line in data:
        total_points = sum(line[1:6])
        grade = get_grade(total_points)
        data.insert(0,total_points)
        data.insert(1,grade)
    return data

I am getting the TypeError: 'float' object is not subscriptable for line 10. I do not understand why as I convert the numbers into ints before I append them into the data list. Can anyone help? Am I being clear enough?

Answer 1

The issue is that you're modifying the data list while you're iterating over it, using data.insert in calculate_grades . This leads to the second iteration of the loop to see the grade value from the previous iteration as line , rather than the list of integers it is expecting.

I don't entirely understand what you're trying to do, so I can't suggest a solution directly. Perhaps you should make a separate list for the output, or modify line in place, rather than inserting a new item into data .

Answer 2

The specific problem is because there are floats in data (eventually)

for line in data:
    total_points = sum(line[1:6])
    grade = get_grade(total_points)
    data.insert(0,total_points)
    data.insert(1,grade)

Because you insert it into your list, as 'grade'

The general problem is that you are modifying your list ('data') while you iterate over it, which is a bad idea - your logic will be hard to read at best, and easily loop forever.

Answer 3

嗯，问题出在第10 line[1:6]的部分line[1:6] 。可变line是浮点数，因此您不能使用子列表。