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631d35bcc2
libs/graph/src/python/basic_graph.cpp, libs/graph/src/python/basic_graph.hpp:
- Allow one to build a graph from anything that looks like a Python list or
tuple.
[SVN r28324]
126 lines
5.0 KiB
HTML
126 lines
5.0 KiB
HTML
<html>
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<head>
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<title>Boost Graph Library: Python Bindings (Experimental)</title>
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<body BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b"
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ALINK="#ff0000">
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<img SRC="../../../boost.png"
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ALT="C++ Boost" width="277" height="86">
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<h1>Boost Graph Library: Python Bindings (<b>Experimental</b>)</h1>
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<p>The Boost Graph Library offers a wealth of graph algorithms and
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data types for C++. These algorithms are flexible and efficient,
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but the mechanisms employed to achieve this goal can result in
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long compile times that slow the development cycle.</p>
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<p>The Python bindings are build using the <a
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href="../../python/doc">Boost.Python</a> library. The bindings are
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meant to strike a balance of usability, flexibility, and
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efficiency, making it possible to rapidly develop useful systems
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using the BGL in Python.</p>
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<h2><a name="caveats">Caveats and Warnings</a></h2>
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<p>The Python bindings for the Graph library are experimental at
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this time. The bindings may not work (but they probably do) and we
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will not attempt to provide backward compatibility if the
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interfaces change. If you have any ideas </p>
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<h2><a name="building">Building the Python Bindings</a></h2>
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<p>To build the Python bindings, change to
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the <tt>libs/graph/build/python</tt> subdirectory of Boost and
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then follow the <a
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href="../../../more/getting_started.html#Build_Install">Boost
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Build Instructions</a> to build the Python extension module. The
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end result will be a dynamic library (DLL, .so, etc.) that can be
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loaded into Python via "<tt>import bgl</tt>". <b>Note</b>: For
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this build to succeed, the graph library must work flawlessly on
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the compile, <i>including the new GraphViz parser</i>, which tends
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to break many popular compilers. For instance, recent versions of
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GCC are okay but Visual C++ 7.1 will crash. We're working to
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resolve the situation.</p>
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<h2><a name="example1">A First Example</a></h2>
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<p>Our <a
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href="../example/python/biconnected_components.py">first
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example</a> illustrates the use of BGL graphs, graph
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algorithms, and property maps from Python. The initial
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step is to load the BGL-Python bindings:</p>
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<pre>
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from bgl import *
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</pre>
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<p>Next, we load a GraphViz file containing the description of a
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sample graph. The <tt>Graph</tt> type is an undirected
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graph; <tt>file_kind</tt> is an enumerator with only two
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potential values: <tt>adjlist</tt>, for an adjacency-list
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representation, or <tt>graphviz</tt>, for a GraphViz file.</p>
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<pre>
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g = Graph("biconnected_components.dot", file_kind.graphviz)
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</pre>
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<p>Assuming no exceptions have been thrown, we will have an
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undirected graph loaded. We can immediately
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call <tt>biconnected_components</tt> to compute the biconnected
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components within the graph:</p>
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<pre>
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art_points = biconnected_components(g, g.get_edge_int_map("label"))
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</pre>
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<p>There are several interesting parts of the preceeding line. We
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call the <a
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href="biconnected_components.html"><tt>biconnected_components</tt></a>
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algorithm with two parameters. The first is just the graph
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itself. The second parameter is a property map from edges to an
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integer value, which will be stored in the graph under the name
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"label". Finally, the return value
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of <tt>biconnected_components</tt> is a Python list containing the
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articulation points of the graph.</p>
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<p>Other kinds of property maps are available. In this case, we
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create two property maps attaching strings to the vertices of the
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graph. We then iterate over all vertices of the graph to set
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default values for each vertex property.</p>
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<pre>
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v_color = g.get_vertex_string_map("fillcolor")
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v_style = g.get_vertex_string_map("style")
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for v in g.vertices:
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v_color[v] = "white"
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v_style[v] = "filled"
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</pre>
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<p>Lastly, we mark all of the articulation points red and write
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out the result in GraphViz format.</p>
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<pre>
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for v in art_points:
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v_color[v] = "red"
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g.write_graphviz("biconnected_components_out.dot")
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</pre>
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<h2><a name="documentation">Documentation style</a></h2>
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<p>
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<HR>
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<TABLE>
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<TR valign=top>
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<TD nowrap>Copyright © 2005</TD><TD>
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<A HREF="../../../people/doug_gregor.html">Doug Gregor</A>, Indiana University (<script language="Javascript">address("cs.indiana.edu", "dgregor")</script>)<br>
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<A HREF=http://www.osl.iu.edu/~lums>Andrew Lumsdaine</A>,
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Indiana University (<script language="Javascript">address("osl.iu.edu", "lums")</script>)
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</TD></TR></TABLE>
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</body>
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</html>
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