4/19/2023 0 Comments Splice 2 d np arrays![]() ![]() The deque iterator has the same internal access to the linked list. Use islice(), as Jacob already demonstrated: elements = islice(mydeque, 5, 12) Your list comprehension is indeed highly inefficient, but there is no need to use indexing. Makes sense to implement slicing in the deque class. So if you are worried about efficiency, it Linked list: elements = for i in range(5, 12)]īut the deque class itself can walk the list and extract the neededĮlements in a single pass. Hand guarantees that each access has to start from the beginning of the If deques are linked lists, as you say, then implementing a slice in theĭeque class can be more efficient than doing it by hand. Sense if they are passed a deque as well, even if the deque is a little List-like sequence: if somebody needs elements 5:12 (say) of a sequence,Īnd it makes sense for a list or a tuple or an array, then it makes The implementation or efficiency doesn’t come into it. The problem of finding the shortest path? Would you conclude thatīecause the algorithms are slow, it “doesn’t make much sense” to solve The known solutions are all very inefficient. The travelling salesman problem is a classic example of a problem where Inefficient (read, takes O(N) time), so slicing those doesn’t make “The deque type is a linked list and indexing past 0 and -1 is Interesting_sub_part = deque( for row in interesting_part]) Interesting_part = deque(islice(stack, 3, 8)) In summary, I want: interesting_part = stack This raises two questions for me: First, why isn’t “2D” list slicing available for python lists? (I realize that I can use numpy and numpy arrays, but (at least to me) this seems like something that should be in the standard library.) Second, why isn’t list slicing notation of any kind allowed on a python deque? Print("Get real, this isn't even allowed with normal python lists.") Print('Some interesting part of a "column" of the stack:', stack)Įxcept TypeError: # though I definitely cannot do this, not even with a list Try: # and even cooler if I could do this Print("Nope, deques can only take an index not slices.") Print("Some interesting part of the stack:", stack) Try: # it would be cool if I could do this Print(stack) # everything is good so far, "2D" deques are allowed! # comb over a bunch of random data and FILO to the stack My dream would be to implement a multidimensional circular buffer (a queue of lists), and access any part of the buffer efficiently and pythonically as illustrated below: from collections import deque here), at least one good source on how to slice a deque, but I cannot find any source on why python does not include multi-dimensional slicing within its standard library or allow slicing notation with a deque. There are numerous sources summarizing python list slice notation (e.g. ![]()
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