Kir*_*ril 2 c++ boost hashmap shared-ptr neural-network
我正在创建一个神经网络,并希望使用hash_map来保持每个神经元的输出神经元的权重参考:
class Neuron; //forward declaration was there (sorry I forgot to show it earlier)
typedef double WEIGHT;
typedef stdext::hash_map<boost::shared_ptr<Neuron>,WEIGHT> NeuronWeightMap;
class Neuron
{
private:
NeuronWeightMap m_outputs;
//...
public:
Neuron();
~Neuron();
//...
WEIGHT GetWeight(const boost::shared_ptr<Neuron>& neuron) const
{
NeuronWeightMap::const_iterator itr = m_outputs.find(neuron);
if( itr != m_outputs.end() )
{
return itr->second;
}
return 0.0f;
}
};
我意识到我不能使用boost :: shared_ptr作为stdext :: hash_map的键,那么另一个建议是什么呢？是否有任何解决方法或是使用不同密钥或切换到std :: map的唯一选择？谢谢!
这是错误:
1>c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(61) : error C2440: 'type cast' : cannot convert from 'const boost::shared_ptr<T>' to 'size_t'
1> with
1> [
1> T=Neuron
1> ]
1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
1> c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(99) : see reference to function template instantiation 'size_t stdext::hash_value<_Kty>(const _Kty &)' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(98) : while compiling class template member function 'size_t stdext::hash_compare<_Kty,_Pr>::operator ()(const _Kty &) const'
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Pr=std::less<boost::shared_ptr<Neuron>>
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\hash_map(80) : see reference to class template instantiation 'stdext::hash_compare<_Kty,_Pr>' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Pr=std::less<boost::shared_ptr<Neuron>>
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(119) : see reference to class template instantiation 'stdext::_Hmap_traits<_Kty,_Ty,_Tr,_Alloc,_Mfl>' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Ty=common_ns::WEIGHT,
1> _Tr=stdext::hash_compare<boost::shared_ptr<Neuron>,std::less<boost::shared_ptr<Neuron>>>,
1> _Alloc=std::allocator<std::pair<const boost::shared_ptr<Neuron>,common_ns::WEIGHT>>,
1> _Mfl=false
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\hash_map(90) : see reference to class template instantiation 'stdext::_Hash<_Traits>' being compiled
1> with
1> [
1> _Traits=stdext::_Hmap_traits<boost::shared_ptr<Neuron>,common_ns::WEIGHT,stdext::hash_compare<boost::shared_ptr<Neuron>,std::less<boost::shared_ptr<Neuron>>>,std::allocator<std::pair<const boost::shared_ptr<Neuron>,common_ns::WEIGHT>>,false>
1> ]
1> FILE_PATH_REMOVED\neuralnet.h(21) : see reference to class template instantiation 'stdext::hash_map<_Kty,_Ty>' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Ty=common_ns::WEIGHT
1> ]
1>NeuralNet.cpp
1>c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(61) : error C2440: 'type cast' : cannot convert from 'const boost::shared_ptr<T>' to 'size_t'
1> with
1> [
1> T=Neuron
1> ]
1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
1> c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(99) : see reference to function template instantiation 'size_t stdext::hash_value<_Kty>(const _Kty &)' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(98) : while compiling class template member function 'size_t stdext::hash_compare<_Kty,_Pr>::operator ()(const _Kty &) const'
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Pr=std::less<boost::shared_ptr<Neuron>>
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\hash_map(80) : see reference to class template instantiation 'stdext::hash_compare<_Kty,_Pr>' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Pr=std::less<boost::shared_ptr<Neuron>>
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\xhash(119) : see reference to class template instantiation 'stdext::_Hmap_traits<_Kty,_Ty,_Tr,_Alloc,_Mfl>' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Ty=common_ns::WEIGHT,
1> _Tr=stdext::hash_compare<boost::shared_ptr<Neuron>,std::less<boost::shared_ptr<Neuron>>>,
1> _Alloc=std::allocator<std::pair<const boost::shared_ptr<Neuron>,common_ns::WEIGHT>>,
1> _Mfl=false
1> ]
1> c:\program files (x86)\microsoft visual studio 8\vc\include\hash_map(90) : see reference to class template instantiation 'stdext::_Hash<_Traits>' being compiled
1> with
1> [
1> _Traits=stdext::_Hmap_traits<boost::shared_ptr<Neuron>,common_ns::WEIGHT,stdext::hash_compare<boost::shared_ptr<Neuron>,std::less<boost::shared_ptr<Neuron>>>,std::allocator<std::pair<const boost::shared_ptr<Neuron>,common_ns::WEIGHT>>,false>
1> ]
1> FILE_PATH_REMOVED\neuralnet.h(21) : see reference to class template instantiation 'stdext::hash_map<_Kty,_Ty>' being compiled
1> with
1> [
1> _Kty=boost::shared_ptr<Neuron>,
1> _Ty=common_ns::WEIGHT
1> ]
1>Generating Code...
Pio*_*sen 11
您可能已Neuron在.h文件中声明.
所以下面可以工作:
struct hasher {
size_t operator()(const boost::shared_ptr<Neuron>& n) { return (size_t)n.get(); }
};
typedef stdext::hash_map<boost::shared_ptr<Neuron>,WEIGHT,hasher> NeuronWeightMap;
问题可能是boost:shared_ptr没有默认的散列函数(看起来像什么？),所以你只需要提供一个.
小智 8
您还可以为哈希提供模板特化:
#include <functional>
#include <boost/shared_ptr.hpp>
template<class T>
class std::tr1::hash<boost::shared_ptr<T>> {
public:
size_t operator()(const boost::shared_ptr<T>& key) const {
return (size_t)key.get();
}
};
与unordered_set完美配合:
class Foo;
typedef boost::shared_ptr<Foo> FooPtr;
typedef std::tr1::unordered_set<FooPtr> FooSet;