PKG-INFO

Metadata-Version: 1.0
Name: pyMCFSimplex
Version: 0.9.1
Summary: pyMCFSimplex is a Python Wrapper for MCFSimplex
Home-page: http:\\www.sommer-forst.de\blog
Author: G#.Blog - Johannes Sommer
Author-email: info@sommer-forst.de
License: LGPL 2.1
Description: 
        *******************************************************************************
        *			          pyMCFSimplex                                *
        *******************************************************************************
        * Version 0.9.1        *
        ************************
        * Johannes Sommer, 2013*
        ************************
        
        1. What?
        --------
        pyMCFSimplex is a Python-Wrapper for the C/C++ MCFSimplex Solver Class from 
        the University of Pisa.
        MCFSimplex is a Class that solves big sized Minimum Cost Flow Problems
        very fast.
        See also [1] for a comparison.
        
        2. How?
        -------
        pyMCFSimplex was being made through SWIG. Don't ask for the time I spent on
        figuring out how SWIG works. With more knowledge in C++ I would have been
        faster - but I'm not a C++ guy! I want it in Python!
        
        3. Who?
        -------
        The authors of MCFSimplex are Alessandro Bertolini and Antonio Frangioni from
        the Operations Research Group at the Dipartimento di Informatica of the 
        University of Pisa [2].
        
        pyMCFSimplex is brought to you by Johannes from the G#.Blog 
        
        	http://www.sommer-forst.de/blog. 
        
        Feel free to contact me: info(at)sommer-forst.de
        
        4. Installation
        ---------------
        Installation prerequisites are:
        - Python 2.7 or Python 2.6 (only Windows)
        - numpy (tested with 1.6.1)
        - a build environment if you want to install from source distribution
        
        4.1 Windows
        -----------
        Select the appropriate MSI package for your installed Python version (2.6 or 2.7) an simply execute the installer.
        
        4.2 Linux
        ---------
        Untar the binary dist package pyMCFSimplex-0.9.1.linux-x86_64.tar.gz with
        
        tar xfvz pyMCFSimplex-0.9.1.linux-x86_64.tar.gz
        
        It will install into /usr/local/lib/python2.7/dist-packages/.
        
        4.3 Source Distribution
        -----------------------
        Grab the pyMCFSimplex-0.9.1_src_dist.zip file, extract it and run
        
        a) linux:
        sudo python setup.py install
        
        b) windows:
        start a command line as Administrator and run
        
        python setup.py install
        
        
        5. Usage
        --------
        Here is a first start. "sample.dmx" must be in the same location of your python script.
        With these lines of code you can parse a minimum cost flow problem in DIMACS file format and solve it.
        
        from pyMCFSimplex import *
        print "pyMCFSimplex Version '%s' successfully imported." % version()
        mcf = MCFSimplex()
        print "MCFSimplex Class successfully instantiated."
        FILENAME = 'sample.dmx'
        print "Loading network from DIMACS file %s.." % FILENAME
        f = open(FILENAME,'r')
        inputStr = f.read()
        f.close()
        mcf.LoadDMX(inputStr)
        
        print "Setting time.."
        mcf.SetMCFTime()
        print "Solving problem.."
        mcf.SolveMCF()
        if mcf.MCFGetStatus() == 0:
            print "Optimal solution: %s" %mcf.MCFGetFO()
            print "Time elapsed: %s sec " %(mcf.TimeMCF())
        else:
            print "Problem unfeasible!"
            print "Time elapsed: %s sec " %(mcf.TimeMCF())
        
        If you want to load a network not from a DIMACS file, you'll have to call LoadNet() while passing C-arrays to the method.
        C arrays in Python? Yes - don't worry. There are helper methods in pyMCFSimplex, that'll do this for you.
        Look at the following piece of code.
        
        mcf = MCFSimplex()
        print "MCFSimplex Class successfully instantiated."
        print "Reading sample data.."
        
        '''
        Problem data of a MCFP in DIMACS notation
        
        c Problem line (nodes, links)
        p min 4 5
        c
        c Node descriptor lines (supply+ or demand-)
        n 1 4
        n 4 -4
        c
        c Arc descriptor lines (from, to, minflow, maxflow, cost)
        a 1 2 0 4 2
        a 1 3 0 2 2
        a 2 3 0 2 1
        a 2 4 0 3 3
        a 3 4 0 5 1
        '''
        
        # MCFP problem transformed to integers and lists
        nmx     = 4 # max number of nodes
        mmx     = 5 # max number of arcs
        pn      = 4 # current number of nodes
        pm      = 5 # current number of arcs
        pU      = [4,2,2,3,5] # column maxflow
        pC      = [2,2,1,3,1] # column cost
        pDfct   = [-4,0,0,4]  # node deficit (supply/demand)
        pSn     = [1,1,2,2,3] # column from
        pEn     = [2,3,3,4,4] # column to
        
        # call LoadNet() with the return values of the helper methods
        # e.g. CreateDoubleArrayFromList(pU) takes a python list and returns a pointer to a 
        # corresponding C array, that is passed as an argument to the method LoadNet()
        mcf.LoadNet(nmx, mmx, pn, pm, CreateDoubleArrayFromList(pU), CreateDoubleArrayFromList(pC),
                    CreateDoubleArrayFromList(pDfct), CreateUIntArrayFromList(pSn),
                    CreateUIntArrayFromList(pEn))
        
        print "Setting time.."
        mcf.SetMCFTime()
        mcf.SolveMCF()
        if mcf.MCFGetStatus() == 0:
            print "Optimal solution: %s" %mcf.MCFGetFO()
            print "Time elapsed: %s sec " %(mcf.TimeMCF())
        else:
            print "Problem unfeasible!"
            print "Time elapsed: %s sec " %(mcf.TimeMCF())
        
        
        Please check out the sample script gsharpblog_mcfsolve_test.py for more information.
        
        
        6. Good to know
        ---------------
        I changed the original source code of MCFClass.h a little bit for SWIG compatibility.
        All changes are marked by the following comment line "//Johannes Sommer".
        This included:
        - LoadDMX() accepts in pyMCFSimplex a string value (original: c iostream). The original LoadDMX method is omitted.
        - as SWIG cannot deal with nested classes, I pulled the classes Inf, MCFState and MCFException out of the main class MCFClass.
        
        Perhaps the above mentioned changes to the original source is not necessary, if you know SWIG very well.
        But I could not figure out how to get these things to work in the SWIG interface file.
        Useful hints are very welcome.
        
        [1] http://bolyai.cs.elte.hu/egres/tr/egres-13-04.ps
        [2] http://www.di.unipi.it/optimize/Software/MCF.html#MCFSimplex
        
Platform: win32
Platform: linux-x86_64