2/10/2024 0 Comments Java for loop iterator syntaxThe above code pretty much defines the way looping works under the hood in Python. We've just reinvented a for loop by using a while loop and iterators. Stop our loop if we got a StopIteration exception while getting the next itemÄef funky_for_loop(iterable, action_to_do):.Execute the body of the for loop if we successfully got the next item.Repeatedly get the next item from the iterator.Get an iterator from the given iterable.We'll do so by attempting to turn this for loop into a while loop: def funky_for_loop(iterable, action_to_do): Now that we've learned about iterators and the iter and next functions, we'll try to manually loop over an iterable without using a for loop. You can take Pez out, but once a Pez is removed it can't be put back, and once the dispenser is empty, it's useless. You can think of iterators as Pez dispensers that cannot be reloaded. And if you pass them to next but they don't have a next item, a StopIteration exception will be raised. The only thing you can do with iterators is ask them for their next item using the next function. So you can get an iterator from every iterable. If you ask for the next item from an iterator and there are no more items, you'll get a StopIteration exception: > next(my_iterator) Iterators are stateful, meaning once you've consumed an item from them, it's gone. Once we have an iterator, the one thing we can do with it is get its next item by passing it to the built-in next function. Passing an iterable to the iter function will always give us back an iterator, no matter what type of iterable we're working with. We can ask each of these iterables for an iterator using Python's built-in iter function. This dictionary has two key-value pairs: > counts = We asked the same question twice and Python gave us two different answers. But if we ask the same question again, Python will tell us that 9 is not in squares. If we ask whether 9 is in our squares generator, Python will tell us that 9 is in squares. Let's take the same list of numbers and the same generator object: > numbers = If we then take the same generator object and pass it to the sum function, we might expect that we'd get the sum of these numbers, which would be 88. We can pass our generator object to the tuple constructor to make a tuple out of it: > tuple(squares) Let's say we have a list of numbers and a generator that will give us the squares of those numbers: > numbers = We're going to start off our journey by taking a look at some "gotchas." After we've learned how looping works in Python, we'll take another look at these gotchas and explain what's going on. In this article we'll dive into Python's for loops to take a look at how they work under the hood and why they work the way they do. Python's for loops don't work the way for loops do in other languages.
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