Why does range(start, end) in Python not include the end value?
For example:
>>> range(1, 11)
gives you:
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Why doesn’t it give a range from 1 to 11, inclusive?
Was this behavior chosen arbitrarily, or is there a specific reason or advantage to this approach that I’m not seeing?
Please explain the reasoning behind this when considering an inclusive range python.
Alright, here’s a bit of insight into why Python’s range(start, end) doesn’t include the end value. So, one of the key reasons for this is zero-indexing compatibility. Most programming languages, including Python, use zero-based indexing. This means the first element starts at index 0. When you call range(1, 11), you’re actually asking for a sequence starting at 1 and stopping just before 11. This makes perfect sense when you’re working with lists or arrays, where the indices also start at 0. For instance, the 10th element in a list has the index 9, not 10. It’s a pattern that maintains consistency across the language, which simplifies the mental model when you’re working with sequences. This also relates directly to how Python handles loops, such as for i in range(start, end), where the loop will run until end-1, making it very predictable for developers.
Exactly, and to add on to that, it all boils down to consistency with slicing in Python. Python’s slicing also follows this pattern. For example, when you slice a list like my_list[1:11], it includes the element at index 1 but excludes the element at index 11. By aligning the behavior of range(start, end) with slicing, Python ensures that the behavior of these operations feels cohesive and intuitive. You can think of it like a natural extension of how you work with lists, so when you start using ranges, it just feels familiar. This approach gives you predictability in your code, and as someone who has spent a lot of time working with lists and sequences, it makes working with loops and slices in Python feel very fluid. It’s a simple but effective way to maintain consistency in operations.
That’s a great point, Charity! And to take it a step further, this behavior also ties into mathematical and algorithmic simplicity. In mathematics, intervals like [1, 11) are defined in a way where the upper bound (11 in this case) is excluded, so Python’s approach to the range(start, end) function aligns perfectly with this concept. It’s a standard convention used in many mathematical algorithms and, by adopting this, Python makes the language feel more natural for anyone with a background in math or algorithms. The idea of an inclusive range python that includes the end value is something you could theoretically implement, but it would go against a well-established convention. Plus, keeping the upper bound excluded avoids ambiguity, especially when working with larger ranges and performing calculations on the elements. This consistency across both mathematical conventions and Python operations makes it easier to reason about your code.