push_back() and push_front() are defined in terms of insert(). Similarly, pop_back() and pop_front() are defined in terms of erase(). Here’s what the C++03 standard says about iterator invalidation for insert() (23.2.1.3/1): An insert in the middle of the deque invalidates all the iterators and references to elements of the deque. An insert at either end … Read more
There’s no built-in Deque container, but there are several implementations available. Here’s a good one from Stephen Cleary. This provides O(1) operations to index and also to insert at the beginning and append at the end. The C# equivalent to Vector is List<T>. Indexed access is O(1), but insertion or removal is O(N) (other than … Read more
I think that these findings below may be useful for both improve the bug report and also for using in your code to workaround the problem. By debugging the optimized output and playing with optimization flags and with minor code changes I’ve reached the conclusion about the specific optimization flags that are causing the error. … Read more
Try itertools.islice(). deque_slice = collections.deque(itertools.islice(my_deque, 10, 20)) Indexing into a deque requires following a linked list from the beginning each time, so the islice() approach, skipping items to get to the start of the slice, will give the best possible performance (better than coding it as an index operation for each element). You could easily … Read more
TL;DR: assuming your deque is called d, just inspect d[0], since the “leftmost” element in a deque is the front (you might want to test before the length of the deque to make sure it’s not empty). Taking @asongtoruin’s suggestion, use if d: to test whether the deque is empty (it’s equivalent to if len(d) … Read more
I found this deque implementation from Wikipedia: Storing contents in multiple smaller arrays, allocating additional arrays at the beginning or end as needed. Indexing is implemented by keeping a dynamic array containing pointers to each of the smaller arrays. I guess it answers my question.
Simply [array insertObject:obj atIndex:0]; Check the documentation
I can’t speak for anybody else, but I can for myself. When I first read about std::deque, I thought it was cool enough that for a while, I treated it not only as the default container, but as nearly the only container I used. Then somebody asked about why, and I expounded at length on … Read more
Deque is short for “double ended queue”. With an ordinary queue, you add things to one end and take them from the other. With a double ended queue, you can add things to either end, and take them from either end. That makes it a bit more versatile; for example, you could use it as … Read more
>>> list(collections.deque((1, 2, 3))) [1, 2, 3]