我目前正在开发一个项目,该项目使用有向超图框架来枚举动态程序的k-best解决方案。我当前的实现(在Python中)运行良好,但速度相当慢。该算法执行许多紧密循环和相当多的递归。我真的认为我可以使用C ++实现实现显着的速度提升。然而,经过一段时间的搜索,我无法找到任何在C ++中提供超图实现的库(特别是有向超图 - 但我甚至无法找到无向超图的库)。有谁知道这样的图书馆?几年前似乎有一个GSoC提议将超图支持提升,但看起来它并没有真正成功。
答案 0 :(得分:8)
我不知道图书馆,但你可以自己动手。
在对代码进行了三天的讨论之后,我终于在MSVC10和GCC(http://ideone.com/oj46o)上没有警告的情况下编译了一个超图。 声明:
#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);
}
说明:
#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();}
}
请注意,这是不经过彻底测试,但它编译并运行我的迷你套件没有错误。 (如IDEOne链接所示)。 Vertex类型和Edge标识符可以是您想要的任何类型,我使用int
椎体和string
边缘标识符进行了测试。
答案 1 :(得分:2)
超图用于统计机器翻译中的解码。在cdec decoder或relax-decode
中实现了超图数据结构和算法一个限制是这些实现中的边有多个尾节点但只有一个头节点。