Python 2.7 Linked List vs List « Python recipes « ActiveState Code

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To cope with this situation we either have to create our own data type, or have to make use of additional Python modules that provide an implementation of such a data type. Stone Soup Programming is dedicated to those who share a passion for learning computer programming and software development.

Of course, Step 2, the recursive call, assumes that we have a way of printing a list backward. Most of the code here we have seen already and we are just reusing code when possible. That could be really useful. To cope with this situation we either have to create our own data type, or have to make use of additional Python modules that provide an implementation of such a data type.

Python Linked List

Well, the conventional wisdom is usually right and so it is in this case. Nonetheless I had an unusual call for a list in which I would often be popping left as well as inserting into and deleting from the middle, while traversing the list item by item, without requiring random access. This is a textbook case for a linked list. I was also curious to extend the new collections library, which is quite well-organized for subclassing. So I decided to write a linked list and compare its performance with the regular list in deleting the linked list in python by popping off the first item repeatedly. On my machine the crossover point was around 5,000 items, becoming an order of magnitude different at 50,000. Of course, deleting a list an item at a time from the beginning is about the worst-case scenario for using a list, and ignores the list's supreme strength for random access, so I hope readers understand that I offer this recipe for instructional purposes. I found myself impressed with the performance of the Python list. Between the optimizations in C and those that occur further down in silicon for block moves, the Python list is a formidable object, even when misused. The handcrafted linked list still has its place in embedded applications, or in applications lacking the container support found in today's frameworks, or linked list in python freshman computer science classes, but in Python the list rules unless one is dealing with huge lists. In the latter case one is better off searching out a specialized library for the occasion rather than using a basic linked list as in this recipe. I added benchmarks for blist and it handles the popleft deletes like a champ, better than my little linked list: Size 100000 Type Create Pop Total List 0.

What's the easiest way to use a linked list in python? By manipulating where the node points, we can expand or shrink the list as needed. Figure 2: Double-linked list A single-linked list can be traversed from head to tail whereas traversing backwards is not as easy as that. Argument x might be a. This method requires a node as an additional parameter. I've made a similar request in the past: in 8 years, zero links except for doubly linked lists used in Raymond Hettinger's ordered set recipe--perhaps, it might be explained that only programmers new to Python read this question--your input would be valuable and highly appreciated. Lists as collections Lists are useful because they provide a way to assemble multiple objects into a single entity, sometimes called a collection.