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Python

Shawn McCall
Shawn McCall
7,863 Points
Posted by Shawn McCall
Shawn McCall
7,863 Points

OOP Python Code Challenge : Using isinstance() function getting a TypeError. Code with sample arg works in Workspaces.

With the sample argument ["apple", 5.2, "dog", 8] provided, I am getting the expected output "applesdog13.2" in workspaces, but in the challenge its giving me a TypeError. What am I missing?

instances.py 
def combiner(arg):
    arg_sum = 0
    arg_string = ""
    for item in arg:
        if (isinstance(item, (int, float))):
            arg_sum += item
            arg.remove(item)
    arg_string = "".join(arg)
    return arg_string + str(arg_sum)

1 Answer

Ryan S
Ryan S
27,276 Points
Ryan S
Ryan S
27,276 Points

Hi Shawn,

You have to be very careful when removing an item from a list while you are iterating through it. Your code works fine for the example given, but if you test your code with a list where an integer occurs twice in a row, you'll get the error you are experiencing.

This is because as an item is removed during iteration, you can end up skipping the next item. If that next item happens to be an int, then you will end up trying to join a list of integers and strings, which will throw a TypeError.

Shawn McCall
Shawn McCall
7,863 Points
Shawn McCall
Shawn McCall
7,863 Points

Ah, I see now. Thank you.