149 lines
4.9 KiB
Python
149 lines
4.9 KiB
Python
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"""
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altgraph - a python graph library
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=================================
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altgraph is a fork of `graphlib <http://pygraphlib.sourceforge.net>`_ tailored
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to use newer Python 2.3+ features, including additional support used by the
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py2app suite (modulegraph and macholib, specifically).
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altgraph is a python based graph (network) representation and manipulation
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package. It has started out as an extension to the
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`graph_lib module
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<http://www.ece.arizona.edu/~denny/python_nest/graph_lib_1.0.1.html>`_
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written by Nathan Denny it has been significantly optimized and expanded.
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The :class:`altgraph.Graph.Graph` class is loosely modeled after the
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`LEDA <http://www.algorithmic-solutions.com/enleda.htm>`_
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(Library of Efficient Datatypes) representation. The library
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includes methods for constructing graphs, BFS and DFS traversals,
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topological sort, finding connected components, shortest paths as well as a
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number graph statistics functions. The library can also visualize graphs
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via `graphviz <http://www.research.att.com/sw/tools/graphviz/>`_.
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The package contains the following modules:
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- the :py:mod:`altgraph.Graph` module contains the
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:class:`~altgraph.Graph.Graph` class that stores the graph data
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- the :py:mod:`altgraph.GraphAlgo` module implements graph algorithms
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operating on graphs (:py:class:`~altgraph.Graph.Graph`} instances)
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- the :py:mod:`altgraph.GraphStat` module contains functions for
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computing statistical measures on graphs
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- the :py:mod:`altgraph.GraphUtil` module contains functions for
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generating, reading and saving graphs
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- the :py:mod:`altgraph.Dot` module contains functions for displaying
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graphs via `graphviz <http://www.research.att.com/sw/tools/graphviz/>`_
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- the :py:mod:`altgraph.ObjectGraph` module implements a graph of
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objects with a unique identifier
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Installation
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------------
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Download and unpack the archive then type::
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python setup.py install
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This will install the library in the default location. For instructions on
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how to customize the install procedure read the output of::
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python setup.py --help install
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To verify that the code works run the test suite::
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python setup.py test
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Example usage
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-------------
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Lets assume that we want to analyze the graph below (links to the full picture)
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GRAPH_IMG. Our script then might look the following way::
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from altgraph import Graph, GraphAlgo, Dot
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# these are the edges
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edges = [ (1,2), (2,4), (1,3), (2,4), (3,4), (4,5), (6,5),
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(6,14), (14,15), (6, 15), (5,7), (7, 8), (7,13), (12,8),
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(8,13), (11,12), (11,9), (13,11), (9,13), (13,10) ]
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# creates the graph
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graph = Graph.Graph()
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for head, tail in edges:
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graph.add_edge(head, tail)
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# do a forward bfs from 1 at most to 20
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print(graph.forw_bfs(1))
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This will print the nodes in some breadth first order::
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[1, 2, 3, 4, 5, 7, 8, 13, 11, 10, 12, 9]
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If we wanted to get the hop-distance from node 1 to node 8
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we coud write::
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print(graph.get_hops(1, 8))
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This will print the following::
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[(1, 0), (2, 1), (3, 1), (4, 2), (5, 3), (7, 4), (8, 5)]
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Node 1 is at 0 hops since it is the starting node, nodes 2,3 are 1 hop away ...
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node 8 is 5 hops away. To find the shortest distance between two nodes you
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can use::
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print(GraphAlgo.shortest_path(graph, 1, 12))
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It will print the nodes on one (if there are more) the shortest paths::
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[1, 2, 4, 5, 7, 13, 11, 12]
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To display the graph we can use the GraphViz backend::
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dot = Dot.Dot(graph)
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# display the graph on the monitor
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dot.display()
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# save it in an image file
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dot.save_img(file_name='graph', file_type='gif')
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..
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@author: U{Istvan Albert<http://www.personal.psu.edu/staff/i/u/iua1/>}
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@license: MIT License
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Copyright (c) 2004 Istvan Albert unless otherwise noted.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to
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deal in the Software without restriction, including without limitation the
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rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom the
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Software is furnished to do so.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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IN THE SOFTWARE.
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@requires: Python 2.3 or higher
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@newfield contributor: Contributors:
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@contributor: U{Reka Albert <http://www.phys.psu.edu/~ralbert/>}
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"""
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import pkg_resources
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__version__ = pkg_resources.require("altgraph")[0].version
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class GraphError(ValueError):
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pass
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