Belle II Software development
LHEReader Class Reference

Class to read LHE files and store the content in a MCParticle graph. More...

#include <LHEReader.h>

Public Member Functions

 BELLE2_DEFINE_EXCEPTION (LHECouldNotOpenFileError, "Could not open file %1% !")
 Exception is thrown if the LHE file could not be opened.
 
 BELLE2_DEFINE_EXCEPTION (LHEInvalidDaughterIndicesError, "Line %1%: Invalid daughter indices d1=%2%, d2=%3%, N=%4% (0<=d1<=d2<=N required)")
 Exception is thrown if the given indices of the daughters are not valid.
 
 BELLE2_DEFINE_EXCEPTION (LHEHeaderNotValidError, "Line %1%: Event header not understood: %2%")
 Exception is thrown if the header specifying the event header could not be parsed.
 
 BELLE2_DEFINE_EXCEPTION (LHEConvertFieldError, "Line %1%: Could not convert field %2%: %3%")
 Exception is thrown if a field in the LHE file could not be converted to a number.
 
 BELLE2_DEFINE_EXCEPTION (LHEParticleFormatError, "Line %1%: Particle format not understood, got %2% fields !")
 Exception is thrown if the format of a line of the LHE file could not be parsed.
 
 BELLE2_DEFINE_EXCEPTION (LHEEmptyEventError, "Line %1%: Number of particles in event is %2% ! (This could mean EOF is reached.) ")
 Exception is thrown if the number of particles for this event is 0 or less.
 
 LHEReader ()
 Constructor.
 
 ~LHEReader ()
 Destructor.
 
void open (const std::string &filename)
 Opens an ascii file and prepares it for reading.
 
void closeCurrentInputFile ()
 Closes the current input file to allow opening the next one.
 
int getEvent (MCParticleGraph &graph, double &weight)
 Reads the next event and stores the result in the given MCParticle graph.
 
bool skipEvents (int n)
 Skips a given number of events.
 
void setInitialIndex (int index)
 Set the maximum index of particles in each event that must be set as c_Initial (1-based).
 
void setVirtualIndex (int index)
 Set the maximum index of particles in each event that must be set as c_IsVirtual (1-based).
 

Public Attributes

bool m_wrongSignPz
 Bool to indicate that HER and LER were swapped.
 
double m_meanDecayLength = 0.
 Mean lifetime*c of displaced particle.
 
double m_Rmin = 0.
 Minimum of vertex distance to IP.
 
double m_Rmax = 0.
 Maximum of vertex distance to IP.
 
int m_pdgDisplaced = 0
 PDG code of the displaced particle being studied.
 

Protected Types

typedef boost::tokenizer< boost::char_separator< char > > tokenizer
 Just a typedef for simple use of the boost::tokenizer to split the lines.
 

Protected Member Functions

std::string getLine ()
 Returns the current line from the LHE ascii file.
 
int readEventHeader (double &eventWeight)
 Reads the event header from the hepevt file.
 
int readParticle (MCParticleGraph::GraphParticle &particle)
 Reads the information for a single particle from the LHE file.
 

Protected Attributes

int m_lineNr
 The current line number within the ascii file.
 
std::ifstream m_input
 The input stream of the ascii file.
 
int m_indexInitial
 Maximum index of particles in each event that must be set as c_Initial (1-based).
 
int m_indexVirtual
 Maximum index of particles in each event that must be set as c_IsVirtual (1-based).
 

Static Protected Attributes

static const boost::char_separator< char > sep
 The characters at which to split, defaults to ",; \t".
 

Detailed Description

Class to read LHE files and store the content in a MCParticle graph.

The class is very similar to the HepEvt Reader

The events are read sequentially with the option of skipping a certain number of events. Random access of events is not possible.

Definition at line 31 of file LHEReader.h.

Member Typedef Documentation

◆ tokenizer

typedef boost::tokenizer<boost::char_separator<char> > tokenizer
protected

Just a typedef for simple use of the boost::tokenizer to split the lines.

Definition at line 110 of file LHEReader.h.

Constructor & Destructor Documentation

◆ LHEReader()

LHEReader ( )
inline

Constructor.

Definition at line 52 of file LHEReader.h.

52 :
53 m_wrongSignPz(false),
54 m_lineNr(0),
55 m_indexInitial(0),
56 m_indexVirtual(0)
57 {}

◆ ~LHEReader()

~LHEReader ( )
inline

Destructor.

Definition at line 62 of file LHEReader.h.

62{ if (m_input) m_input.close(); }

Member Function Documentation

◆ closeCurrentInputFile()

void closeCurrentInputFile ( )
inline

Closes the current input file to allow opening the next one.

Definition at line 73 of file LHEReader.h.

73{m_input.close();}

◆ getEvent()

int getEvent ( MCParticleGraph & graph,
double & weight )

Reads the next event and stores the result in the given MCParticle graph.

Parameters
graphReference to the graph which should be filled with the information from the LHE file.
weightReference to the event weight which can be filled from the file.
Returns
event number if the event could be read and the number was provided in the file.

Definition at line 34 of file LHEReader.cc.

35{
36 int nparticles = readEventHeader(eventWeight);
37 if (nparticles <= 0) {
38 throw (LHEEmptyEventError() << m_lineNr << nparticles);
39 }
40
41 int first = graph.size();
42 //Make list of particles
43 for (int i = 0; i < nparticles; i++) {
44 graph.addParticle();
45 }
46
47 double r, x = 0, y = 0, z = 0, t = 0;
48 //Read particles from file
49 for (int i = 0; i < nparticles; ++i) {
50 MCParticleGraph::GraphParticle& p = graph[first + i];
51 int mother = readParticle(p);
52
53 // add the mother
54 if (mother > 0) {
55 MCParticleGraph::GraphParticle* q = &graph[mother - 1];
56 p.comesFrom(*q);
57 }
58
59 // if positron goes to positive z-direction, we have to rotate along y-axis by 180deg
60 if (m_wrongSignPz) {
61 ROOT::Math::PxPyPzEVector p4 = p.get4Vector();
62 p4.SetPz(-1.0 * p4.Pz());
63 p4.SetPx(-1.0 * p4.Px());
64 p.set4Vector(p4);
65 }
66
67 //move vertex position of selected particle and its daughters
68 if (m_meanDecayLength > 0) {
69 if (p.getPDG() == m_pdgDisplaced) {
70 TF1 fr("fr", "exp(-x/[0])", 0, 1000000);
71 ROOT::Math::PxPyPzEVector p4 = p.get4Vector();
72 fr.SetRange(m_Rmin, m_Rmax);
73 fr.SetParameter(0, m_meanDecayLength * p4.Gamma());
74 r = fr.GetRandom();
75 x = r * p4.Px() / p4.P();
76 y = r * p4.Py() / p4.P();
77 z = r * p4.Pz() / p4.P();
78 p.setDecayVertex(x, y, z);
79 t = (r / Const::speedOfLight) * (p4.E() / p4.P());
80 p.setDecayTime(t);
81 p.setValidVertex(true);
82 }
83
84 if (mother > 0) {
85 if (graph[mother - 1].getPDG() == m_pdgDisplaced) {
86 p.setProductionVertex(x, y, z);
87 p.setProductionTime(t);
88 p.setValidVertex(true);
89 }
90 }
91 }
92
93 // initial 2 (e+/e-), virtual 3 (Z/gamma*)
94 // check if particle should be made virtual according to steering options:
95 if (i < m_indexVirtual && i >= m_indexInitial)
96 p.addStatus(MCParticle::c_IsVirtual);
97
98 if (i < m_indexInitial)
99 p.addStatus(MCParticle::c_Initial);
100
101 if (m_indexVirtual < m_indexInitial) B2WARNING("IsVirtual particle requested but is overwritten by Initial");
102
103 }
104// return eventID;
105 return -1;
106}
static const double speedOfLight
[cm/ns]
Definition Const.h:695
int readParticle(MCParticleGraph::GraphParticle &particle)
Reads the information for a single particle from the LHE file.
Definition LHEReader.cc:190
double m_Rmin
Minimum of vertex distance to IP.
Definition LHEReader.h:104
int m_pdgDisplaced
PDG code of the displaced particle being studied.
Definition LHEReader.h:106
int m_lineNr
The current line number within the ascii file.
Definition LHEReader.h:114
int m_indexVirtual
Maximum index of particles in each event that must be set as c_IsVirtual (1-based).
Definition LHEReader.h:142
double m_Rmax
Maximum of vertex distance to IP.
Definition LHEReader.h:105
int m_indexInitial
Maximum index of particles in each event that must be set as c_Initial (1-based).
Definition LHEReader.h:140
bool m_wrongSignPz
Bool to indicate that HER and LER were swapped.
Definition LHEReader.h:102
int readEventHeader(double &eventWeight)
Reads the event header from the hepevt file.
Definition LHEReader.cc:143
double m_meanDecayLength
Mean lifetime*c of displaced particle.
Definition LHEReader.h:103
size_t size() const
Return the number of particles in the graph.
@ c_Initial
bit 5: Particle is initial such as e+ or e- and not going to Geant4
Definition MCParticle.h:57
@ c_IsVirtual
bit 4: Particle is virtual and not going to Geant4.
Definition MCParticle.h:55
GraphParticle & addParticle()
Add new particle to the graph.

◆ getLine()

std::string getLine ( )
protected

Returns the current line from the LHE ascii file.

  • double eventWeight; /‍**< The event weight if provided in LHEfile else 1. *‍/ *‍/
    Returns
    The current line as a string.

Definition at line 126 of file LHEReader.cc.

127{
128 std::string line;
129 do {
130 getline(m_input, line);
131 m_lineNr++;
132 size_t commentPos = line.find_first_of('#');
133 if (commentPos != string::npos) {
134 line = line.substr(0, commentPos);
135 }
136 boost::trim(line);
137
138 } while (line == "" && !m_input.eof());
139
140 return line;
141}
std::ifstream m_input
The input stream of the ascii file.
Definition LHEReader.h:115

◆ open()

void open ( const std::string & filename)

Opens an ascii file and prepares it for reading.

Parameters
filenameThe filename of the LHE ascii file which should be read.

Definition at line 27 of file LHEReader.cc.

28{
29 m_lineNr = 0;
30 m_input.open(filename.c_str());
31 if (!m_input) throw(LHECouldNotOpenFileError() << filename);
32}

◆ readEventHeader()

int readEventHeader ( double & eventWeight)
protected

Reads the event header from the hepevt file.

Returns
The number of particles for the current event.
Parameters
eventWeightreference to the eventWeight which can both be read from the file.

Definition at line 143 of file LHEReader.cc.

144{
145
146 // Search for next <event>
147 std::string line2;
148 do {
149 getline(m_input, line2);
150 m_lineNr++;
151 size_t commentPos = line2.find_first_of('#');
152 if (commentPos != string::npos) {
153 line2 = line2.substr(0, commentPos);
154 }
155 boost::trim(line2);
156
157 } while (line2 != "<event>" && !m_input.eof());
158
159 //Get number of particles from file
160 int nparticles = -1;
161 string line = getLine();
162
163 if (line == "" || m_input.eof()) return -1;
164
165 vector<double> fields;
166 fields.reserve(15);
167
168 tokenizer tokens(line, sep);
169 int index(0);
170
171 for (const string& tok : tokens) {
172 ++index;
173 try {
174 fields.push_back(boost::lexical_cast<double>(tok));
175 } catch (boost::bad_lexical_cast& e) {
176 throw (LHEConvertFieldError() << m_lineNr << index << tok);
177 }
178 }
179
180 if (fields.size() < 3) {
181 nparticles = static_cast<int>(fields[0]);
182 eventWeight = 1.0;
183 } else {
184 nparticles = static_cast<int>(fields[0]);
185 eventWeight = static_cast<double>(fields[2]);
186 }
187 return nparticles;
188}
std::string getLine()
Returns the current line from the LHE ascii file.
Definition LHEReader.cc:126
static const boost::char_separator< char > sep
The characters at which to split, defaults to ",; \t".
Definition LHEReader.h:112
boost::tokenizer< boost::char_separator< char > > tokenizer
Just a typedef for simple use of the boost::tokenizer to split the lines.
Definition LHEReader.h:110

◆ readParticle()

int readParticle ( MCParticleGraph::GraphParticle & particle)
protected

Reads the information for a single particle from the LHE file.

Parameters
particleReference to the particle which will be filled with the information from the LHE file.

Definition at line 190 of file LHEReader.cc.

191{
192 int mother = -1;
193
194 string line = getLine();
195 vector<double> fields;
196 fields.reserve(15);
197
198 tokenizer tokens(line, sep);
199 int index(0);
200
201 for (const string& tok : tokens) {
202 ++index;
203 try {
204 fields.push_back(boost::lexical_cast<double>(tok));
205 } catch (boost::bad_lexical_cast& e) {
206 throw (LHEConvertFieldError() << m_lineNr << index << tok);
207 }
208 }
209
210 switch (fields.size()) {
211 case 13:
212 particle.addStatus(MCParticle::c_PrimaryParticle);
213 particle.setPDG(static_cast<int>(fields[0]));
214 mother = static_cast<int>(fields[2]);
215 particle.setMomentum(ROOT::Math::XYZVector(fields[6], fields[7], fields[8]));
216 particle.setEnergy(fields[9]);
217 particle.setMass(fields[10]);
218 break;
219 default:
220 throw (LHEParticleFormatError() << m_lineNr << fields.size());
221 }
222
223 return mother;
224}
@ c_PrimaryParticle
bit 0: Particle is primary particle.
Definition MCParticle.h:47

◆ setInitialIndex()

void setInitialIndex ( int index)
inline

Set the maximum index of particles in each event that must be set as c_Initial (1-based).

Parameters
[in]indexMaximum index for c_Initial.

Definition at line 94 of file LHEReader.h.

94{ m_indexInitial = index; }

◆ setVirtualIndex()

void setVirtualIndex ( int index)
inline

Set the maximum index of particles in each event that must be set as c_IsVirtual (1-based).

Parameters
[in]indexMaximum index for c_IsVirtual.

Definition at line 100 of file LHEReader.h.

100{ m_indexVirtual = index; }

◆ skipEvents()

bool skipEvents ( int n)

Skips a given number of events.

Parameters
nThe number of events which should be skipped.
Returns
True if the events could be skipped.

Definition at line 109 of file LHEReader.cc.

110{
111// int eventID;
112 double weight;
113 for (int i = 0; i < n; i++) {
114// int nparticles = readEventHeader(eventID, weight);
115 int nparticles = readEventHeader(weight);
116 if (nparticles < 0) return false;
117 for (int j = 0; j < nparticles; j++) getLine();
118 }
119 return true;
120}

Member Data Documentation

◆ m_indexInitial

int m_indexInitial
protected

Maximum index of particles in each event that must be set as c_Initial (1-based).

Definition at line 140 of file LHEReader.h.

◆ m_indexVirtual

int m_indexVirtual
protected

Maximum index of particles in each event that must be set as c_IsVirtual (1-based).

Definition at line 142 of file LHEReader.h.

◆ m_input

std::ifstream m_input
protected

The input stream of the ascii file.

Definition at line 115 of file LHEReader.h.

◆ m_lineNr

int m_lineNr
protected

The current line number within the ascii file.

Definition at line 114 of file LHEReader.h.

◆ m_meanDecayLength

double m_meanDecayLength = 0.

Mean lifetime*c of displaced particle.

Definition at line 103 of file LHEReader.h.

◆ m_pdgDisplaced

int m_pdgDisplaced = 0

PDG code of the displaced particle being studied.

Definition at line 106 of file LHEReader.h.

◆ m_Rmax

double m_Rmax = 0.

Maximum of vertex distance to IP.

Definition at line 105 of file LHEReader.h.

◆ m_Rmin

double m_Rmin = 0.

Minimum of vertex distance to IP.

Definition at line 104 of file LHEReader.h.

◆ m_wrongSignPz

bool m_wrongSignPz

Bool to indicate that HER and LER were swapped.

Definition at line 102 of file LHEReader.h.

◆ sep

const boost::char_separator< char > sep
staticprotected

The characters at which to split, defaults to ",; \t".

Definition at line 112 of file LHEReader.h.


The documentation for this class was generated from the following files: