// Copyright (C) 2011 Davis E. King (davis@dlib.net)
// License: Boost Software License See LICENSE.txt for the full license.
#ifndef DLIB_PROJECTION_HASh_Hh_
#define DLIB_PROJECTION_HASh_Hh_
#include "projection_hash_abstract.h"
#include "../matrix.h"
#include "../rand.h"
#include <vector>
namespace dlib
{
// ----------------------------------------------------------------------------------------
class projection_hash
{
public:
projection_hash() {}
template <typename EXP1, typename EXP2>
projection_hash(
const matrix_exp<EXP1>& proj_,
const matrix_exp<EXP2>& offset_
) : proj(proj_), offset(offset_)
{
// make sure requires clause is not broken
DLIB_ASSERT(proj.nr() == offset.nr(),
"\t projection_hash::projection_hash()"
<< "\n\t Invalid arguments were given to this function."
<< "\n\t proj.nr(): " << proj.nr()
<< "\n\t offset.nr(): " << offset.nr()
);
}
const matrix<double>& get_projection_matrix (
) const { return proj; }
const matrix<double,0,1>& get_offset_matrix (
) const { return offset; }
unsigned long num_hash_bins (
) const
{
return static_cast<unsigned long>(std::pow(2.0, (double)offset.size()));
}
template <typename EXP>
unsigned long operator() (
const matrix_exp<EXP>& v
) const
{
// make sure requires clause is not broken
DLIB_ASSERT(is_col_vector(v) &&
v.size() == get_projection_matrix().nc() &&
v.size() > 0,
"\t unsigned long projection_hash::operator()(v)"
<< "\n\t Invalid arguments were given to this function."
<< "\n\t is_col_vector(v): " << is_col_vector(v)
<< "\n\t get_projection_matrix().nc(): " << get_projection_matrix().nc()
<< "\n\t v.size(): " << v.size()
);
return do_hash(proj*matrix_cast<double>(v) + offset);
}
private:
template <typename EXP>
unsigned long do_hash (
const matrix_exp<EXP>& v
) const
{
unsigned long h = 0;
for (long i = 0; i < v.size(); ++i)
{
h <<= 1;
if (v(i) > 0)
h |= 1;
}
return h;
}
matrix<double> proj;
matrix<double,0,1> offset;
};
// ----------------------------------------------------------------------------------------
inline void serialize (
const projection_hash& item,
std::ostream& out
)
{
serialize(item.get_projection_matrix(), out);
serialize(item.get_offset_matrix(), out);
}
inline void deserialize (
projection_hash& item,
std::istream& in
)
{
matrix<double> proj;
matrix<double,0,1> offset;
deserialize(proj, in);
deserialize(offset, in);
item = projection_hash(proj, offset);
}
// ----------------------------------------------------------------------------------------
}
#endif // DLIB_PROJECTION_HASh_Hh_