Is there a library that provides a (directed) hypergraph implementation in C++?

I'm currently working on a project that enumerates the k-best solutions of a dynamic program using a directed hypergraph framework. My current implementation (in Python) works well, but is fairly slow. The algorithm performs a number of tight loops and a fair bit of recursion. I really think that I could realize significant speed improvements using a C++ implementation. However, after a fair bit of searching, I was unable to find any libraries that provide hypergraph implementations in C++ (specifically directed hypergraphs -- but I was unable to find even libraries for undirected hypergraphs). Does anyone know of such a library? It seems there was a GSoC proposal to bring hypergraph support to boost a few years ago, but it looks like it didn't really pan out.


ANSWERS:


I don't know of a library, but you could roll your own.

After messing around with the code for three days, I finally got a hypermap to compile without warnings on MSVC10 and GCC().
Declarations:

#include <map>
#include <functional>
#include <memory>

template<class V, class E=int, class PV = std::less<V>, class PE=std::less<E>, class A=std::allocator<V> >
// V is data type of vertex
// E is identifier of Edge
// PV is node sorting predicate
// PE is edge sorting predicate
// A is allocator
class hypergraph {

#if _MSC_VER <= 1600
    typedef A sub_allocator;
#else
    typedef std::scoped_allocator_adaptor<A> sub_allocator;
#endif

public:
    class vertex;
    class edge;
    typedef std::map<V, vertex, PV, sub_allocator> vertexset;
    typedef std::map<E, edge, PE, sub_allocator> edgeset;
    typedef typename vertexset::iterator vertexiter;
    typedef typename edgeset::iterator edgeiter;
    typedef typename vertexset::const_iterator cvertexiter;
    typedef typename edgeset::const_iterator cedgeiter;

    typedef std::reference_wrapper<const V> rwv;
    typedef std::reference_wrapper<const E> rwe;
    typedef std::reference_wrapper<vertex> rwvertex;
    typedef std::reference_wrapper<edge> rwedge;
    typedef std::map<rwv, rwvertex, PV, sub_allocator> ivertexset;
    typedef std::map<rwe, rwedge, PE, sub_allocator> iedgeset;
    typedef typename ivertexset::iterator ivertexiter;
    typedef typename iedgeset::iterator iedgeiter;
    typedef typename ivertexset::const_iterator civertexiter;
    typedef typename iedgeset::const_iterator ciedgeiter;

    class vertex { 
        friend class hypergraph<V,E,PV,PE,A>;
        iedgeset edges_;
        vertex(const PE&, const sub_allocator&);/* so users can'V make their own vertices*/
    public:
        vertex(vertex&&);
        vertex& operator=(vertex&&);
        iedgeset& edges();
        const iedgeset& edges() const;
    };
    class edge { 
        friend class hypergraph<V,E,PV,PE,A>;
        ivertexset vertices_;
        ivertexiter head_;
        edge(const PV&, const sub_allocator&); /* so users can'V make their own edges*/
    public: 
        edge(edge&&);
        edge& operator=(edge&&);
        void set_head(const V& v);
        const V* get_head() const;
        ivertexset& vertices();
        const ivertexset& vertices() const;
    };

    hypergraph(const PV& vertexpred=PV(), const PE& edgepred=PE(), const A& alloc=A());

    std::pair<vertexiter,bool> add_vertex(V v=V());
    std::pair<edgeiter,bool> add_edge(E e=E());
    vertexiter erase_vertex(const vertexiter& iter);
    vertexiter erase_vertex(const V& rhs);
    edgeiter erase_edge(const edgeiter& iter);
    edgeiter erase_edge(const E& rhs);

    void connect(const E& e, const V& v);
    void connect(const edgeiter& ei, const vertexiter& vi);
    void disconnect(const E& e, const V& v);
    void disconnect(const edgeiter& ei, const vertexiter& vi);

    vertexset& vertices();
    const vertexset& vertices() const;
    edgeset& edges();
    const edgeset& edges() const;

    A get_allocator() const;
protected:
    hypergraph(const hypergraph& rhs);
    hypergraph& operator=(const hypergraph& rhs);
    PV pv_;
    PE pe_;
    A a_;
    vertexset vertices_;
    edgeset edges_;
};

namespace std {
    template<class E, class T, class R>
    std::basic_ostream<E,T>& operator<<(std::basic_ostream<E,T>& s, const std::reference_wrapper<R>& r);

    template<class E, class T, class R>
    std::basic_istream<E,T>& operator>>(std::basic_istream<E,T>& s, std::reference_wrapper<R>& r);      
}

Definitions:

#include <algorithm>
#include <cassert>

template<class V, class E, class PV, class PE, class A>
inline hypergraph<V,E,PV,PE,A>::vertex::vertex(const PE& pred, const typename hypergraph<V,E,PV,PE,A>::sub_allocator& alloc) 
    : edges_(pred, alloc)
{}

template<class V, class E, class PV, class PE, class A>
inline hypergraph<V,E,PV,PE,A>::vertex::vertex(typename hypergraph<V,E,PV,PE,A>::vertex&& rhs)
    :  edges_(std::move(rhs.edges_))
{}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::vertex& hypergraph<V,E,PV,PE,A>::vertex::operator=(typename hypergraph<V,E,PV,PE,A>::vertex&& rhs)
{
    edges_ = std::move(rhs);
    return *this;
}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::iedgeset& hypergraph<V,E,PV,PE,A>::vertex::edges()
{return edges_;}

template<class V, class E, class PV, class PE, class A>
inline const typename hypergraph<V,E,PV,PE,A>::iedgeset& hypergraph<V,E,PV,PE,A>::vertex::edges() const
{return edges_;}

template<class V, class E, class PV, class PE, class A>
inline hypergraph<V,E,PV,PE,A>::edge::edge(const PV& pred, const typename hypergraph<V,E,PV,PE,A>::sub_allocator& alloc) 
    : vertices_(pred, alloc)
    , head_(vertices_.end())
{}

template<class V, class E, class PV, class PE, class A>
inline hypergraph<V,E,PV,PE,A>::edge::edge(edge&& rhs)
    : vertices_(rhs.vertices_)
    , head_(rhs.head_!=rhs.vertices_.end() ? vertices_.find(rhs.head_->first) : vertices_.end())
{}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::edge& hypergraph<V,E,PV,PE,A>::edge::operator=(typename hypergraph<V,E,PV,PE,A>::edge&& rhs)
{
    vertices_ = std::move(rhs);
    if (rhs.head_ != rhs.vertices_.end())
        head_ = vertices_.find(rhs.head_->first);
    else
        head_ = vertices_.end();
    return *this;
}

template<class V, class E, class PV, class PE, class A>
inline void hypergraph<V,E,PV,PE,A>::edge::set_head(const V& v)
{
    ivertexiter iter = vertices_.find(std::ref(v));
    assert(iter != vertices_.end());
    head_ = iter;
}

template<class V, class E, class PV, class PE, class A>
inline const V* hypergraph<V,E,PV,PE,A>::edge::get_head() const
{return (head_ != vertices_.end() ? &head_->first.get() : NULL);}

template<class V, class E, class PV, class PE, class A>
inline const typename hypergraph<V,E,PV,PE,A>::ivertexset& hypergraph<V,E,PV,PE,A>::edge::vertices() const
{ return vertices_; }

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::ivertexset& hypergraph<V,E,PV,PE,A>::edge::vertices()
{ return vertices_; }

template<class V, class E, class PV, class PE, class A>
inline hypergraph<V,E,PV,PE,A>::hypergraph(const PV& vertexpred, const PE& edgepred, const A& alloc)
    :pv_(vertexpred)
    ,pe_(edgepred)
    ,a_(alloc)
    ,vertices_(vertexpred, a_)
    ,edges_(edgepred, a_)
{}

template<class V, class E, class PV, class PE, class A>
inline std::pair<typename hypergraph<V,E,PV,PE,A>::vertexiter, bool> hypergraph<V,E,PV,PE,A>::add_vertex(V v)
{ return vertices_.insert(std::pair<V, vertex>(std::move(v),vertex(pe_, a_))); }

template<class V, class E, class PV, class PE, class A>
inline std::pair<typename hypergraph<V,E,PV,PE,A>::edgeiter, bool> hypergraph<V,E,PV,PE,A>::add_edge(E e)
{ return edges_.insert(std::pair<E,edge>(std::move(e), edge(pv_, a_))); }

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::vertexiter hypergraph<V,E,PV,PE,A>::erase_vertex(const typename hypergraph<V,E,PV,PE,A>::vertexiter& iter)
{ 
    for(auto i = iter->edges().begin(); i != iter->edges().end(); ++i)
        i->erase(*iter);
    return vertices_.erase(iter); 
}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::vertexiter hypergraph<V,E,PV,PE,A>::erase_vertex(const V& rhs)
{
    vertexiter vi = vertices_.find(rhs);
    assert(vi != vertices_.end());
    vertex& v = vi->second;
    for(auto i = v.edges().begin(); i != v.edges().end(); ++i)
        i->second.get().vertices_.erase(std::ref(vi->first));
    return vertices_.erase(vi); 
}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::edgeiter hypergraph<V,E,PV,PE,A>::erase_edge(const typename hypergraph<V,E,PV,PE,A>::edgeiter& iter)
{ 
    for(auto i = iter->vertices().begin(); i != iter->vertices().end(); ++i)
        i->edges_.erase(*iter);
    return edges_.erase(iter); 
}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::edgeiter hypergraph<V,E,PV,PE,A>::erase_edge(const E& rhs)
{ 
    edgeiter ei = edges_.find(rhs);
    assert(ei != edges_.end());
    edge& e = ei->second;
    for(auto i = e.vertices().begin(); i != e.vertices().end(); ++i)
        i->second.get().edges_.erase(std::ref(ei->first));
    return edges_.erase(ei); 
}

template<class V, class E, class PV, class PE, class A>
inline void hypergraph<V,E,PV,PE,A>::connect(const E& e, const V& v)
{
    vertexiter vi = vertices_.find(v);
    edgeiter ei = edges_.find(e);
    assert(vi != vertices_.end());
    assert(ei != edges_.end());
    vi->second.edges_.insert(typename iedgeset::value_type(std::ref(ei->first), std::ref(ei->second)));
    auto n = ei->second.vertices_.insert(typename ivertexset::value_type(std::ref(vi->first), std::ref(vi->second)));
    if (ei->second.vertices_.size()==1)
        ei->second.head_ = n.first;
}

template<class V, class E, class PV, class PE, class A>
inline void hypergraph<V,E,PV,PE,A>::connect(const typename hypergraph<V,E,PV,PE,A>::edgeiter& ei, const typename hypergraph<V,E,PV,PE,A>::vertexiter& vi)
{
    assert(std::distance(vertices_.begin(), vi)>=0); //actually asserts that the iterator belongs to this container
    assert(std::distance(edges_.begin(), ei)>=0); //actually asserts that the iterator belongs to this container
    vi->edges_.insert(typename iedgeset::value_type(std::ref(ei->first), std::ref(ei->second)));
    auto n = ei->vertices_.insert(typename ivertexset::value_type(std::ref(vi->first), std::ref(vi->second)));
    if (ei->second.verticies_.size()==1)
        ei->second.head_ = n.first;
}

template<class V, class E, class PV, class PE, class A>
inline void hypergraph<V,E,PV,PE,A>::disconnect(const E& e, const V& v)
{
    edgeiter ei = edges_.find(e);
    vertexiter vi = vertices_.find(v);
    assert(ei != edges.end());
    assert(vi != vertices_.end());
    if (ei->head_.first == v) {
        if (ei->head_ != ei->vertices.begin())
            ei->head = ei->vertices.begin();
        else 
            ei->head = ei->vertices.end();
    }
    ei->vertices_.erase(std::ref(vi->first));
    vi->edges_.erase(std::ref(ei->first));
}

template<class V, class E, class PV, class PE, class A>
inline void hypergraph<V,E,PV,PE,A>::disconnect(const typename hypergraph<V,E,PV,PE,A>::edgeiter& ei, const typename hypergraph<V,E,PV,PE,A>::vertexiter& vi)
{
    assert(std::distance(edges_.begin(), ei)>=0); //actually asserts that the iterator belongs to this container
    assert(std::distance(vertices_.begin(), vi)>=0); //actually asserts that the iterator belongs to this container
    if (ei->head_.first == vi->first) {
        if (ei->head_ != ei->vertices.begin())
            ei->head = ei->vertices.begin();
        else 
            ei->head = ei->vertices.end();
    }
    ei->vertices_.erase(std::ref(vi->first));
    vi->edges_.erase(std::ref(ei->first));
}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::vertexset& hypergraph<V,E,PV,PE,A>::vertices()
{ return vertices_;}

template<class V, class E, class PV, class PE, class A>
inline const typename hypergraph<V,E,PV,PE,A>::vertexset& hypergraph<V,E,PV,PE,A>::vertices() const
{ return vertices_;}

template<class V, class E, class PV, class PE, class A>
inline typename hypergraph<V,E,PV,PE,A>::edgeset& hypergraph<V,E,PV,PE,A>::edges()
{ return edges_;}

template<class V, class E, class PV, class PE, class A>
inline const typename hypergraph<V,E,PV,PE,A>::edgeset& hypergraph<V,E,PV,PE,A>::edges() const
{ return edges_;}

template<class V, class E, class PV, class PE, class A>
inline A hypergraph<V,E,PV,PE,A>::get_allocator() const
{ return a_;}

namespace std {

    template<class E, class T, class R>
    std::basic_ostream<E,T>& operator<<(std::basic_ostream<E,T>& s, const std::reference_wrapper<R>& r) 
    {return s << r.get();}

    template<class E, class T, class R>
    std::basic_istream<E,T>& operator>>(std::basic_istream<E,T>& s, std::reference_wrapper<R>& r) 
    {return s >> r.get();}

}

Note that this is not thoroughly tested, but it compiles and ran through my mini-suite without errors. (As shown in the IDEOne link). The Vertex types and the Edge identifiers can be any types you want, I tested with int verteces and string edge identifiers.


Hypergraphs are used for decoding in statistical machine translation. There are implementations of hypergraph data structures and algorithms in cdec decoder or relax-decode

One limitation is the edges in these implementation have multiple tails node but only a single head node.



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