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Njettiness.cc
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// Nsubjettiness Package
// Questions/Comments? jthaler@jthaler.net
//
// Copyright (c) 2011-14
// Jesse Thaler, Ken Van Tilburg, Christopher K. Vermilion, and TJ Wilkason
//
//----------------------------------------------------------------------
// This file is part of FastJet contrib.
//
// It is free software; you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the
// Free Software Foundation; either version 2 of the License, or (at
// your option) any later version.
//
// It is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
// License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this code. If not, see <http://www.gnu.org/licenses/>.
//----------------------------------------------------------------------
#include "Njettiness.hh"
FASTJET_BEGIN_NAMESPACE // defined in fastjet/internal/base.hh
namespace contrib {
///////
//
// Main Njettiness Class
//
///////
// Helper function to correlate one pass minimization with appropriate measure
void Njettiness::setOnePassAxesFinder(MeasureMode measure_mode, AxesFinder* startingFinder, double beta, double Rcutoff) {
if (measure_mode == normalized_measure || measure_mode == unnormalized_measure || measure_mode == normalized_cutoff_measure || measure_mode == unnormalized_cutoff_measure) {
_axesFinder = new AxesFinderFromOnePassMinimization(startingFinder, beta, Rcutoff);
}
else if (measure_mode == geometric_measure || measure_mode == geometric_cutoff_measure) {
_axesFinder = new AxesFinderFromGeometricMinimization(startingFinder, beta, Rcutoff);
}
else {
std::cerr << "Minimization only set up for normalized_measure, unnormalized_measure, normalized_cutoff_measure, unnormalized_cutoff_measure, geometric_measure, geometric_cutoff_measure" << std::endl;
exit(1); }
}
// Parsing needed for constructor to set AxesFinder and MeasureFunction
// All of the parameter handling is here, and checking that number of parameters is correct.
void Njettiness::setMeasureFunctionandAxesFinder(AxesMode axes_mode, MeasureMode measure_mode, double para1, double para2, double para3, double para4) {
// definition of maximum Rcutoff for non-cutoff measures, changed later by other measures
double Rcutoff = std::numeric_limits<double>::max(); //large number
// Most (but all measures have some kind of beta value)
double beta = NAN;
// The normalized measures have an R0 value.
double R0 = NAN;
// Find the MeasureFunction and set the parameters.
switch (measure_mode) {
case normalized_measure:
beta = para1;
R0 = para2;
if(correctParameterCount(2, para1, para2, para3, para4))
_measureFunction = new DefaultNormalizedMeasure(beta, R0, Rcutoff); //normalized_measure requires 2 parameters, beta and R0
else {
std::cerr << "normalized_measure needs 2 parameters (beta and R0)" << std::endl;
exit(1); }
break;
case unnormalized_measure:
beta = para1;
if(correctParameterCount(1, para1, para2, para3, para4))
_measureFunction = new DefaultUnnormalizedMeasure(beta, Rcutoff); //unnormalized_measure requires 1 parameter, beta
else {
std::cerr << "unnormalized_measure needs 1 parameter (beta)" << std::endl;
exit(1); }
break;
case geometric_measure:
beta = para1;
if(correctParameterCount(1, para1, para2, para3, para4))
_measureFunction = new GeometricMeasure(beta,Rcutoff); //geometric_measure requires 1 parameter, beta
else {
std::cerr << "geometric_measure needs 1 parameter (beta)" << std::endl;
exit(1); }
break;
case normalized_cutoff_measure:
beta = para1;
R0 = para2;
Rcutoff = para3; //Rcutoff parameter is 3rd parameter in normalized_cutoff_measure
if(correctParameterCount(3, para1, para2, para3, para4))
_measureFunction = new DefaultNormalizedMeasure(beta, R0, Rcutoff); //normalized_cutoff_measure requires 3 parameters, beta, R0, and Rcutoff
else {
std::cerr << "normalized_cutoff_measure has 3 parameters (beta, R0, Rcutoff)" << std::endl;
exit(1); }
break;
case unnormalized_cutoff_measure:
beta = para1;
Rcutoff = para2; //Rcutoff parameter is 2nd parameter in normalized_cutoff_measure
if (correctParameterCount(2, para1, para2, para3, para4))
_measureFunction = new DefaultUnnormalizedMeasure(beta, Rcutoff); //unnormalized_cutoff_measure requires 2 parameters, beta and Rcutoff
else {
std::cerr << "unnormalized_cutoff_measure has 2 parameters (beta, Rcutoff)" << std::endl;
exit(1); }
break;
case geometric_cutoff_measure:
beta = para1;
Rcutoff = para2; //Rcutoff parameter is 2nd parameter in geometric_cutoff_measure
if(correctParameterCount(2, para1, para2, para3, para4))
_measureFunction = new GeometricMeasure(beta,Rcutoff); //geometric_cutoff_measure requires 2 parameters, beta and Rcutoff
else {
std::cerr << "geometric_cutoff_measure has 2 parameters (beta,Rcutoff)" << std::endl;
exit(1); }
break;
default:
assert(false);
break;
}
// Choose which AxesFinder from user input.
// Uses setOnePassAxesFinder helpful function to use beta and Rcutoff values about (if needed)
switch (axes_mode) {
case wta_kt_axes:
_axesFinder = new AxesFinderFromWTA_KT();
break;
case wta_ca_axes:
_axesFinder = new AxesFinderFromWTA_CA();
break;
case kt_axes:
_axesFinder = new AxesFinderFromKT();
break;
case ca_axes:
_axesFinder = new AxesFinderFromCA();
break;
case antikt_0p2_axes:
_axesFinder = new AxesFinderFromAntiKT(0.2);
break;
case onepass_wta_kt_axes:
setOnePassAxesFinder(measure_mode, new AxesFinderFromWTA_KT(), beta, Rcutoff);
break;
case onepass_wta_ca_axes:
setOnePassAxesFinder(measure_mode, new AxesFinderFromWTA_CA(), beta, Rcutoff);
break;
case onepass_kt_axes:
setOnePassAxesFinder(measure_mode, new AxesFinderFromKT(), beta, Rcutoff);
break;
case onepass_ca_axes:
setOnePassAxesFinder(measure_mode, new AxesFinderFromCA(), beta, Rcutoff);
break;
case onepass_antikt_0p2_axes:
setOnePassAxesFinder(measure_mode, new AxesFinderFromAntiKT(0.2), beta, Rcutoff);
break;
case onepass_manual_axes:
setOnePassAxesFinder(measure_mode, new AxesFinderFromUserInput(), beta, Rcutoff);
break;
case min_axes: //full minimization is not defined for geometric_measure.
if (measure_mode == normalized_measure || measure_mode == unnormalized_measure || measure_mode == normalized_cutoff_measure || measure_mode == unnormalized_cutoff_measure)
//Defaults to 100 iteration to find minimum
_axesFinder = new AxesFinderFromKmeansMinimization(new AxesFinderFromKT(), beta, Rcutoff, 100);
else {
std::cerr << "Multi-pass minimization only set up for normalized_measure, unnormalized_measure, normalized_cutoff_measure, unnormalized_cutoff_measure." << std::endl;
exit(1);
}
break;
case manual_axes:
_axesFinder = new AxesFinderFromUserInput();
break;
// These options have been commented out because they have not been fully tested
// case wta2_kt_axes: // option for alpha = 2 added
// _axesFinder = new AxesFinderFromWTA2_KT();
// break;
// case wta2_ca_axes: // option for alpha = 2 added
// _axesFinder = new AxesFinderFromWTA2_CA();
// break;
// case onepass_wta2_kt_axes: // option for alpha = 2 added
// setOnePassAxesFinder(measure_mode, new AxesFinderFromWTA2_KT(), beta, Rcutoff);
// break;
// case onepass_wta2_ca_axes: // option for alpha = 2 added
// setOnePassAxesFinder(measure_mode, new AxesFinderFromWTA2_CA(), beta, Rcutoff);
// break;
default:
assert(false);
break;
}
}
// setAxes for Manual mode
void Njettiness::setAxes(std::vector<fastjet::PseudoJet> myAxes) {
if (_current_axes_mode == manual_axes || _current_axes_mode == onepass_manual_axes) {
_currentAxes = myAxes;
}
else {
std::cerr << "You can only use setAxes if using manual_axes or onepass_manual_axes measure mode" << std::endl;
exit(1);
}
}
// Calculates and returns all TauComponents that user would want.
// This information is stored in _current_tau_components for later access as well.
TauComponents Njettiness::getTauComponents(unsigned n_jets, const std::vector<fastjet::PseudoJet> & inputJets) {
if (inputJets.size() <= n_jets) { //if not enough particles, return zero
_currentAxes = inputJets;
_currentAxes.resize(n_jets,fastjet::PseudoJet(0.0,0.0,0.0,0.0));
_current_tau_components = TauComponents();
_seedAxes = _currentAxes;
} else {
_currentAxes = _axesFinder->getAxes(n_jets,inputJets,_currentAxes); // sets current Axes
_seedAxes = _axesFinder->seedAxes(); // sets seed Axes (if one pass minimization was used)
_current_tau_components = _measureFunction->result(inputJets, _currentAxes); // sets current Tau Values
}
return _current_tau_components;
}
// Partition a list of particles according to which N-jettiness axis they are closest to.
// Return a vector of length _currentAxes.size() (which should be N).
// Each vector element is a list of ints corresponding to the indices in
// particles of the particles belonging to that jet.
// TODO: Consider moving to MeasureFunction
std::vector<std::list<int> > Njettiness::getPartition(const std::vector<fastjet::PseudoJet> & particles) {
std::vector<std::list<int> > partitions(_currentAxes.size());
for (unsigned i = 0; i < particles.size(); i++) {
int j_min = -1;
// find minimum distance
double minR = std::numeric_limits<double>::max(); //large number
for (unsigned j = 0; j < _currentAxes.size(); j++) {
double tempR = _measureFunction->jet_distance_squared(particles[i],_currentAxes[j]); // delta R distance
if (tempR < minR) {
minR = tempR;
j_min = j;
}
}
if (_measureFunction->do_cluster(particles[i],_currentAxes[j_min])) partitions[j_min].push_back(i);
}
return partitions;
}
// Having found axes, assign each particle in particles to an axis, and return a set of jets.
// Each jet is the sum of particles closest to an axis (Njet = Naxes).
// TODO: Consider moving to MeasureFunction
std::vector<fastjet::PseudoJet> Njettiness::getJets(const std::vector<fastjet::PseudoJet> & particles) {
std::vector<fastjet::PseudoJet> jets(_currentAxes.size());
std::vector<std::list<int> > partition = getPartition(particles);
for (unsigned j = 0; j < partition.size(); ++j) {
std::list<int>::const_iterator it, itE;
for (it = partition[j].begin(), itE = partition[j].end(); it != itE; ++it) {
jets[j] += particles[*it];
}
}
return jets;
}
} // namespace contrib
FASTJET_END_NAMESPACE

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