Boost Graph Library: Edge List Class

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    edge_list<EdgeIterator, ValueType, DiffType>

The `edge_list` class is an adaptor that turns a pair of edge iterators into a class that models `EdgeListGraph`. The `value_type` of the edge iterator must be a `std::pair` (or at least have `first` and `second` members). The `first_type` and `second_type` of the pair must be the same and they will be used for the graph's `vertex_descriptor`. The `ValueType` and `DiffType` template parameters are only needed if your compiler does not support partial specialization. Otherwise they default to the correct types.

### Example

Applying the Bellman-Ford shortest paths algorithm to an `edge_list`.

      enum { u, v, x, y, z, N };
      char name[] = { 'u', 'v', 'x', 'y', 'z' };

      typedef std::pair<int,int> E;
      E edges[] = { E(u,y), E(u,x), E(u,v),
                    E(v,u),
                    E(x,y), E(x,v),
                    E(y,v), E(y,z),
                    E(z,u), E(z,x) };

      int weight[] = { -4, 8, 5,
                       -2,
                       9, -3,
                       7, 2,
                       6, 7 };

      typedef boost::edge_list<E*> Graph;
      Graph g(edges, edges + sizeof(edges) / sizeof(E));

      std::vector<int> distance(N, std::numeric_limits<short>::max());
      std::vector<int> parent(N,-1);

      distance[z] = 0;
      parent[z] = z;
      bool r = boost::bellman_ford_shortest_paths(g, int(N), weight,
                                                  distance.begin(),
                                                  parent.begin());
      if (r)
        for (int i = 0; i < N; ++i)
          std::cout << name[i] << ": " << distance[i]
                    << " " << name[parent[i]] << std::endl;
      else
        std::cout << "negative cycle" << std::endl;

The output is the distance from the root and the parent of each vertex in the shortest paths tree.

      u: 2 v
      v: 4 x
      x: 7 z
      y: -2 u
      z: 0 z

### Where Defined

`boost/graph/edge_list.hpp`

### Template Parameters

Parameter | Description
--- | ---
`EdgeIterator` | Must be model of InputIterator who's `value_type` must be a pair of vertex descriptors.
`ValueType` | The `value_type` of the `EdgeIterator`. Default: `std::iterator_traits<EdgeIterator>::value_type`
`DiffType` | The `difference_type` of the `EdgeIterator`. Default: `std::iterator_traits<EdgeIterator>::difference_type`

### Model of

EdgeListGraph

### Associated Types

`boost::graph_traits<edge_list>::vertex_descriptor`
The type for the vertex descriptors associated with the `edge_list`. This will be the same type as `std::iterator_traits<EdgeIterator>::value_type::first_type`.

`boost::graph_traits<edge_list>::edge_descriptor`
The type for the edge descriptors associated with the `edge_list`.

`boost::graph_traits<edge_list>::edge_iterator`
The type for the iterators returned by `edges()`. The iterator category of the `edge_iterator` will be the same as that of the `EdgeIterator`.

### Member Functions

`edge_list(EdgeIterator first, EdgeIterator last)`
Creates a graph object with `n` vertices and with the edges specified in the edge list given by the range `[first,last)`.

### Non-Member Functions

`std::pair<edge_iterator, edge_iterator>
edges(const edge_list& g)`
Returns an iterator-range providing access to the edge set of graph `g`.

`vertex_descriptor
source(edge_descriptor e, const edge_list& g)`
Returns the source vertex of edge `e`.

`vertex_descriptor
target(edge_descriptor e, const edge_list& g)`
Returns the target vertex of edge `e`.

Copyright © 2000-2001 | Jeremy Siek, Indiana University (jsiek@osl.iu.edu) Lie-Quan Lee, Indiana University (llee@cs.indiana.edu) Andrew Lumsdaine, Indiana University (lums@osl.iu.edu)