http://code.activestate.com/recipes/users/4177690/2011-04-24T10:55:45-07:00ActiveState Code Recipes2011-04-20T21:50:23-07:00jimmy2timeshttp://code.activestate.com/recipes/users/4177690/http://code.activestate.com/recipes/577666-abstract-method-decorator/

<p style="color: grey"> Python recipe 577666 by <a href="/recipes/users/4177690/">jimmy2times</a> (<a href="/recipes/tags/abstract/">abstract</a>, <a href="/recipes/tags/decorator/">decorator</a>, <a href="/recipes/tags/exception/">exception</a>, <a href="/recipes/tags/inheritance/">inheritance</a>, <a href="/recipes/tags/method/">method</a>, <a href="/recipes/tags/python/">python</a>, <a href="/recipes/tags/subclass/">subclass</a>). Revision 5. </p> <p>A simple decorator that helps define abstract methods: when such a method is called, an appropriate exception is raised.</p>

2011-04-21T13:40:32-07:00jimmy2timeshttp://code.activestate.com/recipes/users/4177690/http://code.activestate.com/recipes/577668-simple-graph-algorithms-with-a-modular-design/

<p style="color: grey"> Python recipe 577668 by <a href="/recipes/users/4177690/">jimmy2times</a> (<a href="/recipes/tags/algorithms/">algorithms</a>, <a href="/recipes/tags/breadth/">breadth</a>, <a href="/recipes/tags/depth/">depth</a>, <a href="/recipes/tags/directed/">directed</a>, <a href="/recipes/tags/first/">first</a>, <a href="/recipes/tags/graph/">graph</a>, <a href="/recipes/tags/object/">object</a>, <a href="/recipes/tags/oriented/">oriented</a>, <a href="/recipes/tags/python/">python</a>, <a href="/recipes/tags/search/">search</a>, <a href="/recipes/tags/theory/">theory</a>, <a href="/recipes/tags/undirected/">undirected</a>, <a href="/recipes/tags/visit/">visit</a>). Revision 7. </p> <p>The purpose of this recipe is to look at algorithmic graph theory from an object-oriented perspective.</p> <p>A graph is built on top of a dictionary indexed by its vertices, each item being the set of neighbours of the key vertex. This ensures that iterating through the neighbours of a vertex is still efficient in sparse graphs (as with adjacency lists) while at the same time checking for adjacency is expected constant-time (as with the adjacency matrix).</p> <p>Any valid class of graph must implement the interface defined by AbstractGraph.</p> <p>A generic search algorithm takes as input a graph, source and target vertices and a queue. A queue must implement the methods Q.get(), Q.put() and Q.empty() in such a way to get the desired order in visiting the vertices.</p> <p>Given this pattern, breadth-first and depth-first search are essentially defined by the corresponding expansion policies: the first one uses an actual FIFO queue, the second one a LIFO queue (or stack).</p>

2011-04-19T15:00:57-07:00jimmy2timeshttp://code.activestate.com/recipes/users/4177690/http://code.activestate.com/recipes/577661-retrieving-the-median-of-a-set-in-constant-time/

<p style="color: grey"> Python recipe 577661 by <a href="/recipes/users/4177690/">jimmy2times</a> (<a href="/recipes/tags/data/">data</a>, <a href="/recipes/tags/heap/">heap</a>, <a href="/recipes/tags/median/">median</a>, <a href="/recipes/tags/python/">python</a>, <a href="/recipes/tags/retrieving/">retrieving</a>, <a href="/recipes/tags/structure/">structure</a>). Revision 2. </p> <p>Provides a data structure for a queue of integers whose get() method returns the median element. The interface is similar to the standard Queue module, with an added method top() to retrieve the median without removing it.</p>

2011-04-24T10:55:45-07:00jimmy2timeshttp://code.activestate.com/recipes/users/4177690/http://code.activestate.com/recipes/577660-representing-a-set-in-a-compact-way/

<p style="color: grey"> Python recipe 577660 by <a href="/recipes/users/4177690/">jimmy2times</a> (<a href="/recipes/tags/compact/">compact</a>, <a href="/recipes/tags/compressed/">compressed</a>, <a href="/recipes/tags/data/">data</a>, <a href="/recipes/tags/python/">python</a>, <a href="/recipes/tags/set/">set</a>, <a href="/recipes/tags/structure/">structure</a>). Revision 5. </p> <p>Implements a data structure for sets of natural numbers, represented by a single integer. The interface is similar to the built-in structure 'set'.</p>