Python: TypeError: 'float' object is not subscriptable

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?

I need to add just the numbers in spots [1:6] from each line — ACx
– ACx, Commented Mar 24, 2015 at 0:56

Blckknght · Accepted Answer · 2015-03-24 00:59:10Z

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.

answered Mar 24, 2015 at 0:59

Blckknght

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Comments

Cireo · Accepted Answer · 2015-03-24 01:02:29Z

1

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.

answered Mar 24, 2015 at 1:02

Cireo

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1 Comment

Cireo Over a year ago

3 Comments

msinghal Over a year ago

I'm not sure why line is a float. It depends on the value of the parameter data that you pass to calculate_grade. It's probably a list of floats, and since line is an element of data, it is also a float.

msinghal Over a year ago

Can you post the full code, so I can see the code that calls calculate_grades?

ACx Over a year ago

fp = open("data.short.txt") data = get_data(fp) grades = calculate_grades(data)

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