Metadata-Version: 1.1
Name: chinesepostman
Version: 0.0.1
Summary: Chinese-Postman network solver
Home-page: https://github.com/supermitch/Chinese-Postman
Author: Mitch LeBlanc
Author-email: supermitch@gmail.com
License: MIT
Description: # Chinese-Postman Solver
        
        I wrote this program to solve the
        [Chinese Postman problem](http://en.wikipedia.org/wiki/Route_inspection_problem).
        
        Described as:
        
        > The **Chinese Postman Problem**, or "route inspection problem"
        > is to find a shortest closed circuit that visits every edge of a
        > (connected) undirected graph.
        
        ## Inspiration
        
        I was inspired to learn about and solve this problem when I thought it would
        be cool to follow every trail in
        [Pacific Spirit Park](http://en.wikipedia.org/wiki/Pacific_Spirit_Regional_Park)
        in one run.
        
        Given that the park contains over 73 km of trail, I need to find the optimum
        Eularian Path. Otherwise it's going to be a really, really long run!
        
        
        ## The Process
        
        The solution is roughly a three-step process:
        
        1. Determine if the graph has an
        [Eularian Path](http://en.wikipedia.org/wiki/Eulerian_path)
            (Very easy)
        2. Make the non-Eularian graph Eularian, at the minimum expense
            (Not so easy)
        3. Find the fudged Eularian path
            (Pretty easy)
        
        ### Solving Minimum Expense
        
        In order to convert a non- or semi-Eularian graph to an Eularian one,
        you must eliminate odd nodes (nodes having an odd number of edges.)
        
        To eliminate an odd node, you need to add another edge to it (essentially
        retracing your steps.) However, this comes as a cost! The goal then is
        to find out which edges to repeat, that eliminate all the odd nodes, with
        the minimum cost.
        
        1. Find all possible combinations of pairs of odd nodes
        2. Using Dijkstra's Algorithm, find the cost of the minimum path between
        those pairs
        3. Find which set of paths (depending on how many odd nodes you have)
        that results in the least total cost
        4. Modify your graph with these new parallel edges
        
        Now you have an Eularian graph with only even nodes, for which an Eularian
        Circuit can be found.
        
        ### Solving the Eularian Circuit
        
        Solving the Eularian Circuit (now that we have one) is relatively easy. At
        first, I simply walked the edges randomly until I happened to find a route
        that either dead-ended, or resulted in a circuit. Then I implemented [Fleury's
        Algorithm](http://en.wikipedia.org/wiki/Eulerian_path#Fleury.27s_algorithm)
        which says always choose a non-bridge over a bridge (for obvious
        reasons). Now it takes very few attempts to solve most circuits.
        
        Later I will implement an alternative circuit finding method (Hierholzer's?)
        
        ## To run
        
            python main.py
        
        If you want to specify which graph to load, simply add the graph name:
        
            python main.py north
        
        You can find all the graph names in the `data` folder.
        
        This program will run in Python 2.7 and Python 3.4, at least.
        
        There are unit tests included, in the `tests` directory. You can run these by
        typing
        
            python tests/run_tests.py
        
        from the root project folder.
        
Keywords: graph network solver postman chinese
Platform: UNKNOWN
Classifier: Development Status :: 3 - Alpha
Classifier: Environment :: Console
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Natural Language :: English
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Topic :: Utilities
