Popular recipes tagged "algorithms" but not "python"

Reversi Othello (Python)

2016-09-19T18:03:09-07:00

Python recipe 580698 by FB36 (ai, algorithm, algorithms, game, games).

Reversi/Othello Board Game using Minimax, Alpha-Beta Pruning, Negamax, Negascout algorithms.

Simple Infix Expression Evaluation (Python)

2015-11-07T18:44:05-08:00

Python recipe 579122 by FB36 (algorithm, algorithms, math, mathematics, stack).

Simple infix expression evaluation using a stack.

Hopfield Artificial Neural Network (C++)

2016-07-03T21:58:49-07:00

C++ recipe 580688 by Jay baller (ai, algorithm, algorithms, artificial_intelligence, neural_network).

(Discrete (Binary)) Hopfield Artificial Neural Network (ANN).

For more info see:

http://en.wikipedia.org/wiki/Hopfield_net

http://www.scholarpedia.org/article/Hopfield_network

Infix Expression Evaluation (Python)

2015-11-08T05:08:26-08:00

Python recipe 579123 by FB36 (algorithm, algorithms, math, mathematics, stack).

Infix expression evaluation using two stacks.

Python A* Pathfinding (With Binary Heap) (Python)

2014-08-06T10:03:01-07:00

Python recipe 578919 by Christian Careaga (algorithms, binary_search). Revision 3.

Implementation of the A-star Pathfinding algorithm in Python, using Binary heap to sort the open list

edge-coloring of a bipartite graph (Python)

2015-07-30T13:40:41-07:00

Python recipe 579088 by Praveen (algorithms).

Konig's theorem tells us that every bipartite graph with maximum vertex-degree d can be edge-colored with just d colors. This recipe relies on a previous recipe by D.Eppstein (123641) : "Hopcroft-Karp bipartite matching".

Priority queue dictionary (Python)

2013-08-25T00:23:12-07:00

Python recipe 578643 by Nezar Abdennur (algorithms, dictionary, heap, heapq, pqdict, priority_queue). Revision 4.

An indexed priority queue implemented in pure python as a dict-like class. It is a stripped-down version of pqdict. A Priority Queue Dictionary maps dictionary keys (dkeys) to updatable priority keys (pkeys).

The priority queue is implemented as a binary heap, which supports:

O(1) access to the top priority element
O(log n) removal of the top priority element
O(log n) insertion of a new element

In addition, an internal dictionary or "index" maps dictionary keys to the position of their entry in the heap. This index is maintained as the heap is manipulated. As a result, a PQ-dict also supports:

O(1) lookup of an arbitrary element's priority key
O(log n) removal of an arbitrary element
O(log n) updating of an arbitrary element's priority key

A data structure like this can be used to drive simulations, schedulers, certain greedy algorithms, merging streams of sorted data, and other applications where priorities may need to be changed frequently.

Knight's Tour using Warnsdorff Algorithm (Python)

2012-12-17T06:04:19-08:00

Python recipe 578382 by FB36 (algorithm, algorithms, math, mathematics).

Knight's Tour using Warnsdorff Algorithm.

Knight's Tour Map using Warnsdorff's Algorithm (Python)

2012-12-18T01:05:51-08:00

Python recipe 578386 by FB36 (algorithm, algorithms, graphics, math, mathematics, pil).

Solves Knight's Tour Problem using Warnsdorff's Algorithm for every square on the chessboard of arbitrary size.

It colors each initial square with a color that depends on the final square coordinates. (This is a method used to create fractals.) Many different formulas maybe used for coloring (based on abs/rel x/y/dist/ang).

Calculating each tour in full creates a highly chaotic image (and takes hours). So I added maxItPercent to cut-off tours earlier. (Using %10 creates an image that has both ordered and chaotic regions.)

Averaging Literal Numbers (Python)

2012-12-06T13:44:42-08:00

Python recipe 578365 by Stephen Chappell (algorithms, demonstration, numbers).

One program that a teacher may assign to beginning programming students would be to take a list of numbers and average them together. This recipe does just that and is designed to be easy to read and follow, showing what is possible with a few lines of Python.

A-star Shortest Path Algorithm (C++)

2010-12-25T23:36:35-08:00

C++ recipe 577457 by FB36 (algorithm, algorithms, game, graph, graphs, routes). Revision 4.

A-star (A*) is a shortest path algorithm widely used for RTS games, GPS navigation etc.

Converts from decimal to any base ( between 2 and 26 ) (Python)

2011-02-24T00:33:07-08:00

Python recipe 577586 by Shashwat Anand (algorithms, base).

This function takes in any base-10 integer and returns the string representation of that number in its specified base-n form. The code was inspired from http://code.activestate.com/recipes/65212-convert-from-decimal-to-any-base-number/ , thereby improving upon it.

Caching decorator with timeout, selective invalidation (Python)

2005-11-05T05:47:03-08:00

Python recipe 442513 by Greg Steffensen (algorithms). Revision 5.

A caching decorator that garbage collects in a separate thread (for performance), allows each cached function to (optionally) set a custom maximum age for entries, and allows individual cache entries to be selectively invalidated.

get all possible combinations of characters given a string (Python)

2011-08-15T04:15:42-07:00

Python recipe 577842 by Yang (algorithms, permutation, string).

This will give a result that is more than a permutation, but all possible combinations. An example is when input is 'abc', the output would be: a,ab,abc,ac,acb,b,ba,bac,bc,bca,c,ca,cab,cb,cba

Shannon-Fano Data Compression (Python)

2010-12-18T22:09:40-08:00

Python recipe 577502 by FB36 (algorithm, algorithms, data_compression). Revision 3.

Shannon-Fano Data Compression. It can compress any kind of file up to 4 GB.

(But trying to compress an already compressed file like zip, jpg etc. can produce a (slightly) larger file though. Shannon-Fano is not the best data compression algorithm anyway.)

Compare algorithms for heapq.smallest (Python)

2011-12-25T23:41:23-08:00

Python recipe 577573 by Raymond Hettinger (algorithms, benchmark, heaps, performance). Revision 3.

General purpose technique for counting comparisons in various searching and sorting applications.

Python Binary Search Tree (Python)

2011-08-08T00:15:09-07:00

Python recipe 577830 by sivarama sarma (algorithms, maximum, minimum, search, sort).

A data structure that holds a sorted collection of values, and supports efficient insertion, deletion, sorted iteration, and min/max finding. Values may sorted either based on their natural ordering, or on a key function (specified as an argument to the search tree's constructor). The search tree may contain duplicate values (or multiple values with equal keys) -- the ordering of such values is undefined.

This implementation was made with efficiency in mind. In particular, it is more than twice as fast as the other native-Python implementations I tried (which all use objects to store search tree nodes).

Binary Search Tree (C++)

2011-08-08T00:13:44-07:00

C++ recipe 577828 by sivarama sarma (algorithm, algorithms, datastructures).

Binary Search Tree.

SleepSort (Timer version) (Python)

2011-06-18T05:37:06-07:00

Python recipe 577762 by wong2 (algorithms, interest, sort).

Python version sleep sort by using threading.Timer

Binary Search Tree (C++)

2011-01-26T22:48:06-08:00

C++ recipe 577552 by FB36 (algorithm, algorithms, datastructures).

Binary Search Tree.