Python Data Structures and Algorithms

Deques

Double-ended queues, or deques (usually pronounced decks), are list-like objects that support thread-safe, memory-efficient appends. Deques are mutable and support some of the operations of lists, such as indexing. Deques can be assigned by index, for example, dq[1] = z; however, we cannot directly slice deques. For example, dq[1:2] results in a TypeError (we will look at a way to return a slice from a deque as a list shortly).

The major advantage of deques over lists is that inserting items at the beginning of a deque is much faster than inserting items at the beginning of a list, although inserting items at the end of a deque is very slightly slower than the equivalent operation on a list. Deques are thread, safe and can be serialized ...