RooFormulaVar.cxx

Go to the documentation of this file.

/*****************************************************************************
 * Project: RooFit                                                           *
 * Package: RooFitCore                                                       *
 * @(#)root/roofitcore:$Id$
 * Authors:                                                                  *
 *   WV, Wouter Verkerke, UC Santa Barbara, verkerke@slac.stanford.edu       *
 *   DK, David Kirkby,    UC Irvine,         dkirkby@uci.edu                 *
 *                                                                           *
 * Copyright (c) 2000-2005, Regents of the University of California          *
 *                          and Stanford University. All rights reserved.    *
 *                                                                           *
 * Redistribution and use in source and binary forms,                        *
 * with or without modification, are permitted according to the terms        *
 * listed in LICENSE (http://roofit.sourceforge.net/license.txt)             *
 *****************************************************************************/
 
//////////////////////////////////////////////////////////////////////////////
/// \class RooFormulaVar
///
/// A RooFormulaVar is a generic implementation of a real-valued object,
/// which takes a RooArgList of servers and a C++ expression string defining how
/// its value should be calculated from the given list of servers.
/// RooFormulaVar uses a RooFormula object to perform the expression evaluation.
///
/// If RooAbsPdf objects are supplied to RooFormulaVar as servers, their
/// raw (unnormalized) values will be evaluated. Use RooGenericPdf, which
/// constructs generic PDF functions, to access their properly normalized
/// values.
///
/// The string expression can be any valid TFormula expression referring to the
/// listed servers either by name or by their ordinal list position. These three are
/// equivalent:
/// ```
///   RooFormulaVar("gen", "x*y", RooArgList(x,y))       // reference by name
///   RooFormulaVar("gen", "@0*@1", RooArgList(x,y))     // reference by ordinal with @
///   RooFormulaVar("gen", "x[0]*x[1]", RooArgList(x,y)) // TFormula-builtin reference by ordinal
/// ```
/// Note that `x[i]` is an expression reserved for TFormula. All variable references
/// are automatically converted to the TFormula-native format. If a variable with
/// the name `x` is given, the RooFormula interprets `x[i]` as a list position,
/// but `x` without brackets as the name of a RooFit object.
///
/// The last two versions, while slightly less readable, are more versatile because
/// the names of the arguments are not hard coded.
///
 
 
#include "Riostream.h"
 
#include "RooFormulaVar.h"
#include "RooStreamParser.h"
#include "RooMsgService.h"
#include "RooTrace.h"
#include "RooFormula.h"
 
#ifdef ROOFIT_LEGACY_EVAL_BACKEND
#include "RooNLLVar.h"
#include "RooChi2Var.h"
#endif
 
using std::cout,std::endl, std::ostream, std::istream, std::list;
 
ClassImp(RooFormulaVar);
 
RooFormulaVar::RooFormulaVar() {}
 
RooFormulaVar::~RooFormulaVar()
{
   if(_formula) delete _formula;
}
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor with formula expression and list of input variables.
/// \param[in] name Name of the formula.
/// \param[in] title Title of the formula.
/// \param[in] inFormula Expression to be evaluated.
/// \param[in] dependents Variables that should be passed to the formula.
/// \param[in] checkVariables Check that all variables from `dependents` are used in the expression.
RooFormulaVar::RooFormulaVar(const char *name, const char *title, const char* inFormula, const RooArgList& dependents,
    bool checkVariables) :
  RooAbsReal(name,title),
  _actualVars("actualVars","Variables used by formula expression",this),
  _formExpr(inFormula)
{
  if (dependents.empty()) {
    _value = traceEval(nullptr);
  } else {
    _formula = new RooFormula(GetName(), _formExpr, dependents, checkVariables);
    _formExpr = _formula->formulaString().c_str();
    _actualVars.add(_formula->actualDependents());
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Constructor with formula expression, title and list of input variables.
/// \param[in] name Name of the formula.
/// \param[in] title Formula expression. Will also be used as the title.
/// \param[in] dependents Variables that should be passed to the formula.
/// \param[in] checkVariables Check that all variables from `dependents` are used in the expression.
RooFormulaVar::RooFormulaVar(const char *name, const char *title, const RooArgList& dependents,
    bool checkVariables) :
  RooAbsReal(name,title),
  _actualVars("actualVars","Variables used by formula expression",this),
  _formExpr(title)
{
  if (dependents.empty()) {
    _value = traceEval(nullptr);
  } else {
    _formula = new RooFormula(GetName(), _formExpr, dependents, checkVariables);
    _formExpr = _formula->formulaString().c_str();
    _actualVars.add(_formula->actualDependents());
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Copy constructor
 
RooFormulaVar::RooFormulaVar(const RooFormulaVar& other, const char* name) :
  RooAbsReal(other, name),
  _actualVars("actualVars",this,other._actualVars),
  _formExpr(other._formExpr)
{
  if (other._formula && other._formula->ok()) {
    _formula = new RooFormula(*other._formula);
    _formExpr = _formula->formulaString().c_str();
  }
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return reference to internal RooFormula object.
/// If it doesn't exist, create it on the fly.
RooFormula& RooFormulaVar::getFormula() const
{
  if (!_formula) {
    // After being read from file, the formula object might not exist, yet:
    _formula = new RooFormula(GetName(), _formExpr, _actualVars);
    const_cast<TString&>(_formExpr) = _formula->formulaString().c_str();
  }
 
  return *_formula;
}
 
 
bool RooFormulaVar::ok() const { return getFormula().ok() ; }
 
 
void RooFormulaVar::dumpFormula() { getFormula().dump() ; }
 
 
////////////////////////////////////////////////////////////////////////////////
/// Calculate current value of object from internal formula
 
double RooFormulaVar::evaluate() const
{
  return getFormula().eval(_actualVars.nset());
}
 
 
void RooFormulaVar::doEval(RooFit::EvalContext &ctx) const
{
   getFormula().doEval(ctx);
}
 
 
////////////////////////////////////////////////////////////////////////////////
/// Propagate server change information to embedded RooFormula object
 
bool RooFormulaVar::redirectServersHook(const RooAbsCollection& newServerList, bool mustReplaceAll, bool nameChange, bool isRecursive)
{
  bool error = getFormula().changeDependents(newServerList,mustReplaceAll,nameChange);
 
  _formExpr = getFormula().GetTitle();
  return error || RooAbsReal::redirectServersHook(newServerList, mustReplaceAll, nameChange, isRecursive);
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Print info about this object to the specified stream.
 
void RooFormulaVar::printMultiline(ostream& os, Int_t contents, bool verbose, TString indent) const
{
  RooAbsReal::printMultiline(os,contents,verbose,indent);
  if(verbose) {
    indent.Append("  ");
    os << indent;
    getFormula().printMultiline(os,contents,verbose,indent);
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Add formula expression as meta argument in printing interface
 
void RooFormulaVar::printMetaArgs(ostream& os) const
{
  os << "formula=\"" << _formExpr << "\" " ;
}
 
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Read object contents from given stream
 
bool RooFormulaVar::readFromStream(istream& /*is*/, bool /*compact*/, bool /*verbose*/)
{
  coutE(InputArguments) << "RooFormulaVar::readFromStream(" << GetName() << "): can't read" << endl ;
  return true ;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Write object contents to given stream
 
void RooFormulaVar::writeToStream(ostream& os, bool compact) const
{
  if (compact) {
    cout << getVal() << endl ;
  } else {
    os << GetTitle() ;
  }
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Forward the plot sampling hint from the p.d.f. that defines the observable obs
 
std::list<double>* RooFormulaVar::binBoundaries(RooAbsRealLValue& obs, double xlo, double xhi) const
{
  for (const auto par : _actualVars) {
    auto func = static_cast<const RooAbsReal*>(par);
    list<double>* binb = nullptr;
 
    if (func && (binb = func->binBoundaries(obs,xlo,xhi)) ) {
      return binb;
    }
  }
 
  return nullptr;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Forward the plot sampling hint from the p.d.f. that defines the observable obs
 
std::list<double>* RooFormulaVar::plotSamplingHint(RooAbsRealLValue& obs, double xlo, double xhi) const
{
  for (const auto par : _actualVars) {
    auto func = dynamic_cast<const RooAbsReal*>(par);
    list<double>* hint = nullptr;
 
    if (func && (hint = func->plotSamplingHint(obs,xlo,xhi)) ) {
      return hint;
    }
  }
 
  return nullptr;
}
 
 
 
////////////////////////////////////////////////////////////////////////////////
/// Return the default error level for MINUIT error analysis
/// If the formula contains one or more RooNLLVars and
/// no RooChi2Vars, return the defaultErrorLevel() of
/// RooNLLVar. If the addition contains one ore more RooChi2Vars
/// and no RooNLLVars, return the defaultErrorLevel() of
/// RooChi2Var. If the addition contains neither or both
/// issue a warning message and return a value of 1
 
double RooFormulaVar::defaultErrorLevel() const
{
  RooAbsReal* nllArg(nullptr) ;
  RooAbsReal* chi2Arg(nullptr) ;
 
#ifdef ROOFIT_LEGACY_EVAL_BACKEND
  for (const auto arg : _actualVars) {
    if (dynamic_cast<RooNLLVar*>(arg)) {
      nllArg = static_cast<RooAbsReal*>(arg) ;
    }
    if (dynamic_cast<RooChi2Var*>(arg)) {
      chi2Arg = static_cast<RooAbsReal*>(arg) ;
    }
  }
#endif
 
  if (nllArg && !chi2Arg) {
    coutI(Minimization) << "RooFormulaVar::defaultErrorLevel(" << GetName()
         << ") Formula contains a RooNLLVar, using its error level" << endl ;
    return nllArg->defaultErrorLevel() ;
  } else if (chi2Arg && !nllArg) {
    coutI(Minimization) << "RooFormulaVar::defaultErrorLevel(" << GetName()
    << ") Formula contains a RooChi2Var, using its error level" << endl ;
    return chi2Arg->defaultErrorLevel() ;
  } else if (!nllArg && !chi2Arg) {
    coutI(Minimization) << "RooFormulaVar::defaultErrorLevel(" << GetName() << ") WARNING: "
            << "Formula contains neither RooNLLVar nor RooChi2Var server, using default level of 1.0" << endl ;
  } else {
    coutI(Minimization) << "RooFormulaVar::defaultErrorLevel(" << GetName() << ") WARNING: "
         << "Formula contains BOTH RooNLLVar and RooChi2Var server, using default level of 1.0" << endl ;
  }
 
  return 1.0 ;
}
 
void RooFormulaVar::translate(RooFit::Detail::CodeSquashContext &ctx) const
{
   // If the number of elements to sum is less than 3, just build a sum expression.
   // Otherwise build a loop to sum over the values.
   unsigned int eleSize = _actualVars.size();
   std::string className = GetName();
   std::string varName = "elements" + className;
   std::string sumName = "sum" + className;
   std::string code;
   std::string decl = "double " + varName + "[" + std::to_string(eleSize) + "]{";
   int idx = 0;
   for (RooAbsArg *it : _actualVars) {
      decl += ctx.getResult(*it) + ",";
      ctx.addResult(it, varName + "[" + std::to_string(idx) + "]");
      idx++;
   }
   decl.back() = '}';
   code += decl + ";\n";
 
   ctx.addResult(this, (_formula->getTFormula()->GetUniqueFuncName() + "(" + varName + ")").Data());
 
   ctx.addToCodeBody(this, code);
}