What is wrong with my code checking for arithmetic sequence eligibility?

Question

When inputting a list of numbers, they would always result in True

def arithmetic(lst):
    for i in range(0,len(lst)-1):
        if (lst[i+1] - lst[i]) != (lst[i+2] - lst[i+1]):
            return False
        return True

Asked By: Superheroo2

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Source

Answer 1

Since your return True statement is inside the for loop it’s gonna return true on the first iteration of the loop (even if the if condition is false).

You should remove indentation from that line, so that the return True is in the function, but NOT in the for loop.

Like this:

def arithmetic(lst):
    for i in range(0,len(lst)-1):
        if (lst[i+1] - lst[i]) != (lst[i+2] - lst[i+1]):
            return False
    return True

But as mentioned by others in the comments this code will fail, cause you are trying to access elements outside the list. Hint i+2 is the issue.

Homework would be:

fix iteration issue by proper indexing
think of better argument name and don’t use abbreviations
[OPTIONAL] by convention functions returning bool start with is_, are_ and so on, it improves readability imho

Answered By: Gameplay

What is wrong with my code checking for arithmetic sequence eligibility?

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