Python 错误：“IndexError：列表索引超出范围”

Question

I'm trying to sort a score by average with data I retrieve from a CSV file, but when I run my code it throws the error :

row[1] = int(row[1])
IndexError: list index out of range

The code I have looks like this:

print("Would you like to see previous results?")
    print("Press 1 to see previous results for your class. Press 2 to close the program")
    answer = int(input())
    if answer == 1:
        print("How would you like data to be sorted?")
        print("Press 1 for average")
        print("Press 2 for highest to lowest")
        print("Press 3 for alphabetically")
        sort_num = int(input())
        if sort_num == 1:
            f = open("Class 2.csv")
            csv_f = csv.reader(f)
            newlist = []
            for row in csv_f:
                row[1] = int(row[1])
                row[2] = int(row[2])
                row[3] = int(row[3])

                average = round(sum(row[1:3])/3)
                row.append(average)
                newlist.append(row[0:4])
            print(newlist)

Could anyone explain why I have this error an show where I'm going wrong?

Answer 1

Try to print the content of row before performing the issued operation.

f = open("Class 2.csv")
        csv_f = csv.reader(f)
        newlist = []
        for row in csv_f:
            print("row == {} // type(row) == {}".format(row, type(row)))
            row[1] = int(row[1])
            row[2] = int(row[2])
            row[3] = int(row[3])

If row is void or contains only an element, and in this last case you have to access to element 0 (in code: row[0]), you got this type of error.

The printing of type of row is to verify the type of row (yet, I don't think that row has a type different from 'list')

Hope this helps you :-)