Python 2.6+ and Python 3: If you want StopIteration to be raised if no matching element is found: next(x for x in the_iterable if x > 3) If you want default_value (e.g. None) to be returned instead: next((x for x in the_iterable if x > 3), default_value) Note that you need an extra pair of … Read more
I debated answering this for a while, because similar questions have been asked many times here. But it’s just unique enough to be given the benefit of the doubt. (Still, I won’t object if others vote to close.) Here’s a visual explanation of what is happening. [0, 1, 2, 3, 4, 5, 6, 7, 8, … Read more
Use an Iterator and call remove(): Iterator<String> iter = myArrayList.iterator(); while (iter.hasNext()) { String str = iter.next(); if (someCondition) iter.remove(); }
Python 3.6 version of the above answer, using os – assuming that you have the directory path as a str object in a variable called directory_in_str: import os directory = os.fsencode(directory_in_str) for file in os.listdir(directory): filename = os.fsdecode(file) if filename.endswith(“.asm”) or filename.endswith(“.py”): # print(os.path.join(directory, filename)) continue else: continue Or recursively, using pathlib: from pathlib import … Read more
To safely remove from a collection while iterating over it you should use an Iterator. For example: List<String> names = …. Iterator<String> i = names.iterator(); while (i.hasNext()) { String s = i.next(); // must be called before you can call i.remove() // Do something i.remove(); } From the Java Documentation : The iterators returned by … Read more
It’s because data is an iterator, and you can consume an iterator only once. For example: lst = [1, 2, 3] it = iter(lst) next(it) => 1 next(it) => 2 next(it) => 3 next(it) => StopIteration If we are traversing some data using a for loop, that last StopIteration will cause it to exit the … Read more
Iterator objects in python conform to the iterator protocol, which basically means they provide two methods: __iter__() and __next__(). The __iter__ returns the iterator object and is implicitly called at the start of loops. The __next__() method returns the next value and is implicitly called at each loop increment. This method raises a StopIteration exception … Read more
Never alter the container you’re looping on, because iterators on that container are not going to be informed of your alterations and, as you’ve noticed, that’s quite likely to produce a very different loop and/or an incorrect one. In normal cases, looping on a copy of the container helps, but in your case it’s clear … Read more
Iteration is a general term for taking each item of something, one after another. Any time you use a loop, explicit or implicit, to go over a group of items, that is iteration. In Python, iterable and iterator have specific meanings. An iterable is an object that has an __iter__ method which returns an iterator, … Read more
C++03 (Source: Iterator Invalidation Rules (C++03)) Insertion Sequence containers vector: all iterators and references before the point of insertion are unaffected, unless the new container size is greater than the previous capacity (in which case all iterators and references are invalidated) [23.2.4.3/1] deque: all iterators and references are invalidated, unless the inserted member is at … Read more