CODEWITHSUNDEEP
pythonsequence
Amidokian37
Amidokian37

Reputation: 11

min() arg is an empty sequence, what to to if no number goes into my def

Hi I have a problem with my code and I don't know how to solve it. The challenge is :"How many consecutive numbers are needed?" ... to fill an array. Example: [1, 2, 4, 6] the answer should be 2. This is what I got.

def consecutive(arr):
    arr.sort()
    minimum = min(arr)
    maximum = max(arr)

    diff = maximum - minimum - len(arr) + 1

    return diff

the proble is when arr is [] then it doesnt work. What can I change about my code.

Upvotes: 0

Views: 969

Answers (2)

chepner
chepner

Reputation: 530990

You can only compute the minimum and maximum of a non-empty list, so you have two alternatives: raise an exception if the input is empty, or provide a default value to return in the case of an empty list. (Both cases defer to the caller to decide what is needed if the list is empty, rather than forcing the function to guess at an appropriate value.)

  1. Raise an exception.

    def consecutive(arr):
    if not arr:
        raise ValueError("List is empty")

    minimum = min(arr)
    maximum = max(arr)

    diff = maximum - minimum - len(arr) + 1

    return diff

  2. Provide a default

    def consecutive(arr, if_empty=None):
    if not arr:
        return if_empty

    minimum = min(arr)
    maximum = max(arr)

    diff = maximum - minimum - len(arr) + 1

    return diff

Note that in neither case do you have to sort the list first; both min and max handle unsorted lists just fine.

Upvotes: 1

piterbarg
piterbarg

Reputation: 8219

Maybe I am reading too much into the question, but the answers provided so far, as well as the OP's own answer, are wrong if arr has repeated elements such as [1,2,2,6]. So the correct answer, 'borrowing'' error handling code from @chepner, is

def consecutive(arr):
    if not arr:
        raise ValueError("List is empty")

    minimum = min(arr)
    maximum = max(arr)

    diff = maximum - minimum - len(set(arr)) + 1

    return diff

Here set(arr) returns unique elements of arr

Upvotes: 0

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