<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"> <!-- Copyright © 2009 Trustees of Indiana University Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) --> <html> <head> <title>Boost Graph Library: Grid Graph</title> <style type="text/css"> <!-- body { color: black; background-color: white; } a { color: blue; } a:visited { color: #551A8B; } .code { border-left-style: groove; border-left-width: 1px; padding-left: 2em; } --> </style> </head> <body> <img src="../../../boost.png" alt="C++ Boost" width="277" height="86" /> <br /> <h1> <tt>grid_graph</tt> </h1> <ul> <li><a href="#overview">Overview</a></li> <li><a href="#creating">Creating a Grid Graph</a></li> <li><a href="#indexing">Indexing</a></li> <li><a href="#member">Grid Graph Member Functions</a></li> </ul> <h3 id="overview">Overview</h3> <p> A <tt>grid_graph</tt> represents a multi-dimensional, rectangular grid of vertices with user-defined dimension lengths and wrapping. </p> <p> <tt>grid_graph</tt> models: <ul> <li><a href="IncidenceGraph.html">Incidence Graph</a></li> <li><a href="AdjacencyGraph.html">Adjacency Graph</a></li> <li><a href="VertexListGraph.html">Vertex List Graph</a></li> <li><a href="EdgeListGraph.html">Edge List Graph</a></li> <li><a href="BidirectionalGraph.html">Bidirectional Graph</a></li> <li><a href="AdjacencyMatrix.html">Adjacency Matrix</a></li> </ul> </p> <p> Defined in <a href="../../../boost/graph/grid_graph.hpp"><tt>boost/graph/grid_graph.hpp</tt></a> with all functions in the <tt>boost</tt> namespace. All examples are available in a single program file in <a href="../../../libs/graph/example/grid_graph_example.cpp"><tt>libs/graph/example/grid_graph_example.cpp</tt></a> </p> <h4>Template Parameters</h4> <pre class="code"> <span class="keyword">template</span> <<span class="name">std</span>::<span class="type">size_t</span> <span class="name">Dimensions</span>, <span class="keyword">typename</span> <span class="name">VertexIndex</span> = <span class="name">std</span>::<span class="type">size_t</span>, <span class="keyword">typename</span> <span class="name">EdgeIndex</span> = <span class="name">VertexIndex</span>> <span class="keyword">class</span> grid_graph; </pre> <ul> <li> <tt>Dimensions</tt> - Number of dimensions in the graph, <b>must be greater than 2</b> </li> <li> <tt>VertexIndex</tt> - Type used for vertex indices, defaults to std::size_t </li> <li> <tt>EdgeIndex</tt> - Type used for edge indices, defaults to the same type as VertexIndex </li> </ul> <h3 id="creating">Creating a Grid Graph</h3> <p> The constructor to <tt>grid_graph</tt> has several overloads to aid in configuring each dimension: </p> <pre class="code"> <span class="comment">// Defines a grid_graph that does not wrap.</span> <span class="type">grid_graph</span><...>(<span class="name">boost</span>:<span class="type">array</span><<span class="name">VertexIndex</span>, <span class="name">Dimensions</span>> dimension_lengths); <span class="comment">// Defines a grid_graph where all dimensions are either wrapped or unwrapped.</span> <span class="type">grid_graph</span><...>(<span class="name">boost</span>:<span class="type">array</span><<span class="name">VertexIndex</span>, <span class="name">Dimensions</span>> dimension_lengths, <span class="keyword">bool</span> wrap_all_dimensions); <span class="comment">// Defines a grid_graph where the wrapping for each dimension is specified individually.</span> <span class="type">grid_graph</span><...>(<span class="name">boost</span>:<span class="type">array</span><<span class="name">VertexIndex</span>, <span class="name">Dimensions</span>> dimension_lengths, <span class="name">boost</span>:<span class="type">array</span><<span class="keyword">bool</span>, <span class="name">Dimensions</span>> wrap_dimension); </pre> <h4>Example</h4> <pre class="code"> <span class="comment">// Define dimension lengths, a 3x3 in this case</span> <span class="name">boost</span>::<span class="type">array</span><<span class="keyword">int</span>, <span class="literal">2</span>> lengths = { { <span class="literal">3</span>, <span class="literal">3</span> } }; <span class="comment">// Create a 3x3 two-dimensional, unwrapped grid graph (Figure 1)</span> <span class="type">grid_graph</span><<span class="literal">2</span>> graph(lengths); <span class="comment">// Create a 3x3 two-dimensional, wrapped grid graph (Figure 2)</span> <span class="type">grid_graph</span><<span class="literal">2</span>> graph(lengths, <span class="keyword">true</span>); </pre> <p style="margin-left: 10px;"> <img src="figs/grid_graph_unwrapped.png" /> <br /> <em style="font-size: 0.8em"><b>Figure 1:</b> A 3x3 two-dimensional, unwrapped grid graph</em> </p> <br /> <p style="margin-left: 10px;"> <img src="figs/grid_graph_wrapped.png" /> <br /> <em style="font-size: 0.8em"><b>Figure 2:</b> A 3x3 two-dimensional, wrapped grid graph</em> </p> <br /> <h3 id="indexing">Indexing</h3> <p> The <tt>grid_graph</tt> supports addressing vertices and edges by index. The following functions allow you to convert between vertices, edges, and their associated indices: </p> <pre class="code"> <span class="keyword">typedef</span> <span class="type">grid_graph</span><...> <span class="name">Graph</span>; <span class="keyword">typedef</span> <span class="type">graph_traits</span><<span class="name">Graph</span>> <span class="name">Traits</span>; <span class="comment">// Get the vertex associated with vertex_index</span> <span class="name">Traits</span>::<span class="type">vertex_descriptor</span> vertex(<span class="name">Traits</span>::<span class="type">vertices_size_type</span> vertex_index, <span class="keyword">const</span> <span class="name">Graph&</span> graph); <span class="comment">// Get the index associated with vertex</span> <span class="name">Traits</span>::<span class="type">vertices_size_type</span> get(<span class="name">boost</span>::<span class="type">vertex_index_t</span>, <span class="keyword">const</span> <span class="name">Graph&</span> graph, <span class="name">Traits</span>::<span class="type">vertex_descriptor</span> vertex); <span class="comment">// Get the edge associated with edge_index</span> <span class="name">Traits</span>::<span class="type">edge_descriptor</span> edge_at(<span class="name">Traits</span>::<span class="type">edges_size_type</span> edge_index, <span class="keyword">const</span> <span class="name">Graph&</span> graph); <span class="comment">// Get the index associated with edge</span> <span class="name">Traits</span>::<span class="type">edges_size_type</span> get(<span class="name">boost</span>::<span class="type">edge_index_t</span>, <span class="keyword">const</span> <span class="name">Graph&</span> graph, <span class="name">Traits</span>::<span class="type">edge_descriptor</span> edge); <span class="comment">// Get the out-edge associated with vertex and out_edge_index</span> <span class="name">Traits</span>::<span class="type">edge_descriptor</span> out_edge_at(<span class="name">Traits</span>::<span class="type">vertex_descriptor</span> vertex, <span class="name">Traits</span>::<span class="type">degree_size_type</span> out_edge_index, <span class="keyword">const</span> <span class="name">Graph&</span> graph); <span class="comment">// Get the out-edge associated with vertex and in_edge_index</span> <span class="name">Traits</span>::<span class="type">edge_descriptor</span> in_edge_at(<span class="name">Traits</span>::<span class="type">vertex_descriptor</span> vertex, <span class="name">Traits</span>::<span class="type">degree_size_type</span> in_edge_index, <span class="keyword">const</span> <span class="name">Graph&</span> graph); </pre> <h4>Example</h4> <pre class="code"> <span class="keyword">typedef</span> <span class="type">grid_graph</span><2> <span class="name">Graph</span>; <span class="keyword">typedef</span> <span class="type">graph_traits</span><<span class="name">Graph</span>> <span class="name">Traits</span>; <span class="comment">// Create a 3x3, unwrapped grid_graph (Figure 3)</span> <span class="name">boost</span>::<span class="type">array</span><<span class="keyword">int</span>, <span class="literal">2</span>> lengths = { { <span class="literal">3</span>, <span class="literal">3</span> } }; <span class="name">Graph</span> graph(lengths); <span class="comment">// Do a round-trip test of the vertex index functions</span> <span class="keyword">for</span> (<span class="name">Traits</span>::<span class="type">vertices_size_type</span> v_index = <span class="literal">0</span>; v_index < num_vertices(graph); ++v_index) { <span class="comment">// The two indices should always be equal</span> <span class="name">std</span>::cout << <span class="literal">"Index of vertex "</span> << v_index << <span class="literal">" is "</span> << get(<span class="name">boost</span>::vertex_index, graph, vertex(v_index, graph)) << <span class="name">std</span>::endl; } <span class="comment">// Do a round-trip test of the edge index functions</span> <span class="keyword">for</span> (<span class="name">Traits</span>::<span class="type">edges_size_type</span> e_index = <span class="literal">0</span>; e_index < num_edges(graph); ++e_index) { <span class="comment">// The two indices should always be equal</span> <span class="name">std</span>::cout << <span class="literal">"Index of edge "</span> << e_index << <span class="literal">" is "</span> << get(<span class="name">boost</span>::edge_index, graph, edge_at(e_index, graph)) << <span class="name">std</span>::endl; } </pre> <p style="margin-left: 10px;"> <img src="figs/grid_graph_indexed.png" /> <br /> <em style="font-size: 0.8em"><b>Figure 3:</b> 3x3 unwrapped grid_graph with vertex and edge indices shown.</em> </p> <br /> <h3 id="member">Member Functions</h3> <p> There are several <tt>grid_graph</tt> specific member functions available: </p> <pre class="code"> <span class="keyword">typedef</span> <span class="type">grid_graph</span><...> <span class="name">Graph</span>; <span class="keyword">typedef</span> <span class="type">graph_traits</span><<span class="name">Graph</span>> <span class="name">Traits</span>; <span class="comment">// Returns the number of dimensions</span> <span class="name">std</span>::<span class="type">size_t</span> dimensions(); <span class="comment">// Returns the length of a dimension</span> <span class="name">Traits</span>::<span class="type">vertices_size_type</span> length(<span class="name">std</span>::<span class="type">size_t</span> dimension); <span class="comment">// Returns true if the dimension wraps, false if not</span> <span class="keyword">bool</span> wrapped(<span class="name">std</span>::<span class="type">size_t</span> dimension); <span class="comment">// Returns the "next" vertex in a dimension at a given distance. If the dimension // is unwrapped, next will stop at the last vertex in the dimension. </span><span class="name">Traits</span>::<span class="type">vertex_descriptor</span> next(<span class="name">Traits</span>::<span class="type">vertex_descriptor</span> vertex, <span class="name">std</span>::<span class="type">size_t</span> dimension, <span class="name">Traits</span>::<span class="type">vertices_size_type</span> distance = <span class="literal">1</span>); <span class="comment">// Returns the "previous" vertex in a dimension at a given distance. If the // dimension is unwrapped, previous will stop at the beginning vertex in the dimension. </span><span class="name">Traits</span>::<span class="type">vertex_descriptor</span> previous(<span class="name">Traits</span>::<span class="type">vertex_descriptor</span> vertex, <span class="name">std</span>::<span class="type">size_t</span> dimension, <span class="name">Traits</span>::<span class="type">vertices_size_type</span> distance = <span class="literal">1</span>); </pre> <h4>Example</h4> <pre class="code"> <span class="keyword">typedef</span> <span class="type">grid_graph</span><<span class="literal">3</span>> <span class="name">Graph</span>; <span class="keyword">typedef</span> <span class="type">graph_traits</span><<span class="name">Graph</span>> <span class="name">Traits</span>; <span class="comment">// Define a 3x5x7 grid_graph where the second dimension doesn't wrap</span> <span class="name">boost</span>::<span class="type">array</span><<span class="name">std</span>::<span class="type">size_t</span>, <span class="literal">3</span>> lengths = { { <span class="literal">3</span>, <span class="literal">5</span>, <span class="literal">7</span> } }; <span class="name">boost</span>::<span class="type">array</span><<span class="keyword">bool</span>, <span class="literal">3</span>> wrapped = { { <span class="keyword">true</span>, <span class="keyword">false</span>, <span class="keyword">true</span> } }; <span class="name">Graph</span> graph(lengths, wrapped); <span class="comment">// Print number of dimensions</span> <span class="name">std</span>::cout << graph.dimensions() << <span class="name">std</span>::endl; <span class="comment">// prints "3"</span> <span class="comment">// Print dimension lengths (same order as in the lengths array)</span> <span class="name">std</span>::cout << graph.length(<span class="literal">0</span>) << <span class="literal">"x"</span> << graph.length(<span class="literal">1</span>) << <span class="literal">"x"</span> << graph.length(<span class="literal">2</span>) << <span class="name">std</span>::endl; <span class="comment">// prints "3x5x7"</span> <span class="comment">// Print dimension wrapping (W = wrapped, U = unwrapped)</span> <span class="name">std</span>::cout << graph.wrapped(<span class="literal">0</span>) ? <span class="literal">"W"</span> : <span class="literal">"U"</span> << <span class="literal">", "</span> << graph.wrapped(<span class="literal">1</span>) ? <span class="literal">"W"</span> : <span class="literal">"U"</span> << <span class="literal">", "</span> << graph.wrapped(<span class="literal">2</span>) ? <span class="literal">"W"</span> : <span class="literal">"U"</span> << <span class="name">std</span>::endl; <span class="comment">// prints "W, U, W"</span> <span class="comment">// Define a simple function to print vertices</span> <span class="keyword">void</span> print_vertex(<span class="name">Traits</span>::<span class="type">vertex_descriptor</span> vertex_to_print) { <span class="name">std</span>::cout << <span class="literal">"("</span> << vertex_to_print[<span class="literal">0</span>] << <span class="literal">", "</span> << vertex_to_print[<span class="literal">1</span>] << <span class="literal">", "</span> << vertex_to_print[<span class="literal">2</span>] << <span class="literal">")"</span> << <span class="name">std</span>::endl; } <span class="comment">// Start with the first vertex in the graph</span> <span class="name">Traits</span>::<span class="type">vertex_descriptor</span> first_vertex = vertex(<span class="literal">0</span>, graph); print_vertex(first_vertex); <span class="comment">// prints "(0, 0, 0)"</span> <span class="comment">// Print the next vertex in dimension 0</span> print_vertex(graph.next(first_vertex, <span class="literal">0</span>)); <span class="comment">// prints "(1, 0, 0)"</span> <span class="comment">// Print the next vertex in dimension 1</span> print_vertex(graph.next(first_vertex, <span class="literal">1</span>)); <span class="comment">// prints "(0, 1, 0)"</span> <span class="comment">// Print the 5th next vertex in dimension 2</span> print_vertex(graph.next(first_vertex, <span class="literal">2</span>, <span class="literal">5</span>)); <span class="comment">// prints "(0, 0, 5)"</span> <span class="comment">// Print the previous vertex in dimension 0 (wraps)</span> print_vertex(graph.previous(first_vertex, <span class="literal">0</span>)); <span class="comment">// prints "(2, 0, 0)"</span> <span class="comment">// Print the previous vertex in dimension 1 (doesn't wrap, so it's the same)</span> print_vertex(graph.previous(first_vertex, <span class="literal">1</span>)); <span class="comment">// prints "(0, 0, 0)"</span> <span class="comment">// Print the 20th previous vertex in dimension 2 (wraps around twice)</span> print_vertex(graph.previous(first_vertex, <span class="literal">2</span>, <span class="literal">20</span>)); <span class="comment">// prints "(0, 0, 1)"</span> </pre> <hr /> Copyright © 2009 Trustees of Indiana University </body> </html>