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HomogeneousKernelMap.cpp
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HomogeneousKernelMap.cpp
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/*
* This software is distributed under BSD 3-clause license (see LICENSE file).
*
* Authors: Viktor Gal, Sergey Lisitsyn, Soeren Sonnenburg, Heiko Strathmann,
* Evgeniy Andreev, Evan Shelhamer, Bjoern Esser
*/
#include <shogun/io/SGIO.h>
#include <shogun/mathematics/Math.h>
#include <shogun/preprocessor/HomogeneousKernelMap.h>
using namespace shogun;
CHomogeneousKernelMap::CHomogeneousKernelMap()
: CDensePreprocessor<float64_t>(),
m_kernel(HomogeneousKernelIntersection),
m_window(HomogeneousKernelMapWindowRectangular),
m_gamma(1.0),
m_period(-1),
m_order(1)
{
init ();
register_params ();
}
CHomogeneousKernelMap::CHomogeneousKernelMap(HomogeneousKernelType kernel,
HomogeneousKernelMapWindowType wType, float64_t gamma,
uint64_t order, float64_t period)
: CDensePreprocessor<float64_t>(),
m_kernel(kernel),
m_window(wType),
m_gamma(gamma),
m_period(period),
m_order(order)
{
init ();
register_params ();
}
CHomogeneousKernelMap::~CHomogeneousKernelMap()
{
}
void CHomogeneousKernelMap::cleanup()
{
m_table=SGVector<float64_t>();
}
void CHomogeneousKernelMap::init()
{
SG_DEBUG ("Initialising homogeneous kernel map...\n")
ASSERT (m_gamma > 0)
ASSERT (m_kernel == HomogeneousKernelIntersection ||
m_kernel == HomogeneousKernelChi2 ||
m_kernel == HomogeneousKernelJS);
ASSERT (m_window == HomogeneousKernelMapWindowUniform ||
m_window == HomogeneousKernelMapWindowRectangular);
if (m_period < 0) {
switch (m_window) {
case HomogeneousKernelMapWindowUniform:
switch (m_kernel) {
case HomogeneousKernelChi2:
m_period =
5.86 * std::sqrt(static_cast<float64_t>(m_order)) +
3.65;
break;
case HomogeneousKernelJS:
m_period =
6.64 * std::sqrt(static_cast<float64_t>(m_order)) +
7.24;
break;
case HomogeneousKernelIntersection:
m_period = 2.38 * std::log(m_order + 0.8) + 5.6;
break;
}
break;
case HomogeneousKernelMapWindowRectangular:
switch (m_kernel)
{
case HomogeneousKernelChi2:
m_period = 8.80 * std::sqrt(m_order + 4.44) - 12.6;
break;
case HomogeneousKernelJS:
m_period = 9.63 * std::sqrt(m_order + 1.00) - 2.93;
break;
case HomogeneousKernelIntersection:
m_period = 2.00 * std::log(m_order + 0.99) + 3.52;
break;
}
break;
}
m_period = CMath::max (m_period, 1.0) ;
}
m_numSubdivisions = 8 + 8*m_order;
m_subdivision = 1.0 / m_numSubdivisions;
m_minExponent = -20;
m_maxExponent = 8;
int tableHeight = 2*m_order + 1 ;
int tableWidth = m_numSubdivisions * (m_maxExponent - m_minExponent + 1);
size_t numElements = (tableHeight * tableWidth + 2*(1+m_order));
if (unsigned(m_table.vlen) != numElements) {
SG_DEBUG ("reallocating... %d -> %d\n", m_table.vlen, numElements)
m_table.vector = SG_REALLOC (float64_t, m_table.vector, m_table.vlen, numElements);
m_table.vlen = numElements;
}
int exponent;
uint64_t i = 0, j = 0;
float64_t* tablep = m_table.vector;
float64_t* kappa = m_table.vector + tableHeight * tableWidth;
float64_t* freq = kappa + (1+m_order);
float64_t L = 2.0 * CMath::PI / m_period;
/* precompute the sampled periodicized spectrum */
while (i <= m_order) {
freq[i] = j;
kappa[i] = get_smooth_spectrum (j * L);
++ j;
if (kappa[i] > 0 || j >= 3*i) ++ i;
}
/* fill table */
for (exponent = m_minExponent ;
exponent <= m_maxExponent ; ++ exponent) {
float64_t x, Lxgamma, Llogx, xgamma;
float64_t sqrt2kappaLxgamma;
float64_t mantissa = 1.0;
for (i = 0 ; i < m_numSubdivisions;
++i, mantissa += m_subdivision) {
x = std::ldexp (mantissa, exponent);
xgamma = CMath::pow (x, m_gamma);
Lxgamma = L * xgamma;
Llogx = L * std::log(x);
*tablep++ = std::sqrt(Lxgamma * kappa[0]);
for (j = 1 ; j <= m_order; ++j) {
sqrt2kappaLxgamma = std::sqrt(2.0 * Lxgamma * kappa[j]);
*tablep++ = sqrt2kappaLxgamma * std::cos(freq[j] * Llogx);
*tablep++ = sqrt2kappaLxgamma * std::sin(freq[j] * Llogx);
}
} /* next mantissa */
} /* next exponent */
}
SGMatrix<float64_t> CHomogeneousKernelMap::apply_to_feature_matrix (CFeatures* features)
{
auto simple_features = features->as<CDenseFeatures<float64_t>>();
int32_t num_vectors = simple_features->get_num_vectors ();
int32_t num_features = simple_features->get_num_features ();
SGMatrix<float64_t> feature_matrix(num_features*(2*m_order+1),num_vectors);
for (int i = 0; i < num_vectors; ++i)
{
SGVector<float64_t> transformed = apply_to_vector(simple_features->get_feature_vector(i));
for (int j=0; j<transformed.vlen; j++)
feature_matrix(j,i) = transformed[j];
}
simple_features->set_feature_matrix(feature_matrix);
return feature_matrix;
}
/// apply preproc on single feature vector
SGVector<float64_t> CHomogeneousKernelMap::apply_to_feature_vector(SGVector<float64_t> vector)
{
SGVector<float64_t> result = apply_to_vector(vector);
return result;
}
void CHomogeneousKernelMap::set_kernel_type(HomogeneousKernelType k)
{
m_kernel = k;
init ();
}
HomogeneousKernelType CHomogeneousKernelMap::get_kernel_type() const
{
return m_kernel;
}
void CHomogeneousKernelMap::set_window_type(HomogeneousKernelMapWindowType w)
{
m_window = w;
init ();
}
HomogeneousKernelMapWindowType CHomogeneousKernelMap::get_window_type() const
{
return m_window;
}
void CHomogeneousKernelMap::set_gamma(float64_t g)
{
m_gamma = g;
init ();
}
float64_t CHomogeneousKernelMap::get_gamma(float64_t g) const
{
return m_gamma;
}
void CHomogeneousKernelMap::set_order(uint64_t o)
{
m_order = o;
init ();
}
uint64_t CHomogeneousKernelMap::get_order() const
{
return m_order;
}
void CHomogeneousKernelMap::set_period(float64_t p)
{
m_period = p;
init ();
}
float64_t CHomogeneousKernelMap::get_period() const
{
return m_period;
}
inline float64_t
CHomogeneousKernelMap::get_spectrum(float64_t omega) const
{
switch (m_kernel) {
case HomogeneousKernelIntersection:
return (2.0 / CMath::PI) / (1 + 4 * omega*omega);
case HomogeneousKernelChi2:
return 2.0 /
(std::exp(CMath::PI * omega) + std::exp(-CMath::PI * omega));
case HomogeneousKernelJS:
return (2.0 / std::log(4.0)) * 2.0 /
(std::exp(CMath::PI * omega) +
std::exp(-CMath::PI * omega)) /
(1 + 4 * omega * omega);
default:
/* throw exception */
throw ShogunException(
"CHomogeneousKernelMap::get_spectrum: no "
"valid kernel has been set!");
}
}
inline float64_t
CHomogeneousKernelMap::sinc(float64_t x) const
{
if (x == 0.0) return 1.0 ;
return std::sin(x) / x;
}
inline float64_t
CHomogeneousKernelMap::get_smooth_spectrum(float64_t omega) const
{
float64_t kappa_hat = 0;
float64_t omegap ;
float64_t epsilon = 1e-2;
float64_t const omegaRange = 2.0 / (m_period * epsilon);
float64_t const domega = 2 * omegaRange / (2 * 1024.0 + 1);
switch (m_window) {
case HomogeneousKernelMapWindowUniform:
kappa_hat = get_spectrum (omega);
break;
case HomogeneousKernelMapWindowRectangular:
for (omegap = - omegaRange ; omegap <= omegaRange ; omegap += domega) {
float64_t win = sinc ((m_period/2.0) * omegap);
win *= (m_period/(2.0*CMath::PI));
kappa_hat += win * get_spectrum (omegap + omega);
}
kappa_hat *= domega;
/* project on the postivie orthant (see PAMI) */
kappa_hat = CMath::max (kappa_hat, 0.0);
break;
default:
/* throw exception */
throw ShogunException ("CHomogeneousKernelMap::get_smooth_spectrum: no valid kernel has been set!");
}
return kappa_hat;
}
SGVector<float64_t> CHomogeneousKernelMap::apply_to_vector(const SGVector<float64_t>& in_v) const
{
/* assert for in vector */
ASSERT (in_v.vlen > 0)
ASSERT (in_v.vector != NULL)
uint64_t featureDimension = 2*m_order+1;
SGVector<float64_t> out_v(featureDimension*in_v.vlen);
for (int k = 0; k < in_v.vlen; ++k) {
/* break value into exponent and mantissa */
int exponent;
int unsigned j;
float64_t mantissa = std::frexp (in_v[k], &exponent);
float64_t sign = (mantissa >= 0.0) ? +1.0 : -1.0;
mantissa *= 2*sign;
exponent -- ;
if (mantissa == 0 ||
exponent <= m_minExponent ||
exponent >= m_maxExponent)
{
for (j = 0 ; j <= m_order ; ++j) {
out_v[k*featureDimension+j] = 0.0;
}
continue;
}
//uint64_t featureDimension = 2*m_order+1;
float64_t const * v1 = m_table.vector +
(exponent - m_minExponent) * m_numSubdivisions * featureDimension;
float64_t const * v2;
float64_t f1, f2;
mantissa -= 1.0;
while (mantissa >= m_subdivision) {
mantissa -= m_subdivision;
v1 += featureDimension;
}
v2 = v1 + featureDimension;
for (j = 0 ; j < featureDimension ; ++j) {
f1 = *v1++;
f2 = *v2++;
out_v[k*featureDimension+j] = sign * ((f2 - f1) * (m_numSubdivisions * mantissa) + f1);
}
}
return out_v;
}
void CHomogeneousKernelMap::register_params()
{
/* register variables */
SG_ADD((machine_int_t*) &m_kernel, "kernel", "Kernel type to use.",MS_AVAILABLE);
SG_ADD((machine_int_t*) &m_window, "window", "Window type to use.",MS_AVAILABLE);
SG_ADD(&m_gamma, "gamma", "Homogeneity order.",MS_AVAILABLE);
SG_ADD(&m_period, "period", "Approximation order",MS_NOT_AVAILABLE);
SG_ADD(&m_numSubdivisions, "num_subdivisions", "The number of sublevels",MS_NOT_AVAILABLE);
SG_ADD(&m_subdivision, "subdivision", "subdivision.",MS_NOT_AVAILABLE);
SG_ADD(&m_order, "order", "The order",MS_AVAILABLE);
SG_ADD(&m_minExponent, "min_exponent", "Minimum exponent",MS_NOT_AVAILABLE);
SG_ADD(&m_maxExponent, "max_exponent", "Maximum exponent",MS_NOT_AVAILABLE);
SG_ADD(&m_table, "table", "Lookup-table",MS_NOT_AVAILABLE);
}