Internally uses ROOT's TFormula to compute user-defined expressions of RooAbsArgs.

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 forms equivalent:

RooFormula("formula", "x*y",       RooArgList(x,y))  or
RooFormula("formula", "@0*@1",     RooArgList(x,y))
RooFormula("formula", "x[0]*x[1]", RooArgList(x,y))

Note that x[i] is an expression reserved for TFormula. If a variable with the name x is given, the RooFormula interprets x as a variable name, but x[i] as an index in the list of variables.

Category expressions

State information of RooAbsCategories can be accessed using the '::' operator, i.e.*, tagCat::Kaon will resolve to the numerical value of the Kaon state of the RooAbsCategory object named tagCat.

A formula to switch between lepton categories could look like this:

RooFormula("formulaWithCat",
  "x * (leptonMulti == leptonMulti::one) + y * (leptonMulti == leptonMulti::two)",
  RooArgList(x, y, leptonMulti));

Debugging a formula that won't compile

When the formula is preprocessed, RooFit can print information in the debug stream. These can be retrieved by activating the RooFit::MsgLevel RooFit::DEBUG and the RooFit::MsgTopic RooFit::InputArguments. Check the tutorial rf506_msgservice.C for details.

Definition at line 27 of file RooFormula.h.

Public Member Functions
	RooFormula (const char name, const char formula, const RooArgList &varList, bool checkVariables=true)
	Construct a new formula.

	RooFormula (const RooFormula &other, const char *name=nullptr)
	Copy constructor.

RooArgSet	actualDependents () const
	Return list of arguments which are used in the formula.

bool	changeDependents (const RooAbsCollection &newDeps, bool mustReplaceAll, bool nameChange)
	Change used variables to those with the same name in given list.

TObject *	Clone (const char *newName=nullptr) const override
	Make a clone of an object using the Streamer facility.

void	doEval (RooFit::EvalContext &) const

void	dump () const
	DEBUG: Dump state information.

double	eval (const RooArgSet *nset=nullptr) const
	Evaluate all parameters/observables, and then evaluate formula.

std::string	formulaString () const

RooAbsArg *	getParameter (const char *name) const
	Return pointer to the parameter with given name.

RooAbsArg *	getParameter (Int_t index) const
	Return pointer to parameter at given index.

TFormula *	getTFormula () const

bool	ok () const

RooFormula &	operator= (const RooFormula &other)=delete

RooFormula &	operator= (RooFormula &&other)=delete

void	Print (Option_t *options=nullptr) const override
	This method must be overridden when a class wants to print itself.

void	printArgs (std::ostream &os) const override
	Print arguments of formula, i.e. dependents that are actually used.

void	printClassName (std::ostream &os) const override
	Print class name of formula.

void	printMultiline (std::ostream &os, Int_t contents, bool verbose=false, TString indent="") const override
	Printing interface.

void	printName (std::ostream &os) const override
	Print name of formula.

void	printTitle (std::ostream &os) const override
	Print title of formula.

void	printValue (std::ostream &os) const override
	Print value of formula.

Public Member Functions inherited from TNamed
	TNamed ()

	TNamed (const char name, const char title)

	TNamed (const TNamed &named)
	TNamed copy ctor.

	TNamed (const TString &name, const TString &title)

virtual	~TNamed ()
	TNamed destructor.

void	Clear (Option_t *option="") override
	Set name and title to empty strings ("").

TObject *	Clone (const char *newname="") const override
	Make a clone of an object using the Streamer facility.

Int_t	Compare (const TObject *obj) const override
	Compare two TNamed objects.

void	Copy (TObject &named) const override
	Copy this to obj.

virtual void	FillBuffer (char *&buffer)
	Encode TNamed into output buffer.

const char *	GetName () const override
	Returns name of object.

const char *	GetTitle () const override
	Returns title of object.

ULong_t	Hash () const override
	Return hash value for this object.

TClass *	IsA () const override

Bool_t	IsSortable () const override

void	ls (Option_t *option="") const override
	List TNamed name and title.

TNamed &	operator= (const TNamed &rhs)
	TNamed assignment operator.

void	Print (Option_t *option="") const override
	Print TNamed name and title.

virtual void	SetName (const char *name)
	Set the name of the TNamed.

virtual void	SetNameTitle (const char name, const char title)
	Set all the TNamed parameters (name and title).

virtual void	SetTitle (const char *title="")
	Set the title of the TNamed.

virtual Int_t	Sizeof () const
	Return size of the TNamed part of the TObject.

void	Streamer (TBuffer &) override
	Stream an object of class TObject.

void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

Public Member Functions inherited from TObject
	TObject ()
	TObject constructor.

	TObject (const TObject &object)
	TObject copy ctor.

virtual	~TObject ()
	TObject destructor.

void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract.

virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad.

virtual void	Browse (TBrowser *b)
	Browse object. May be overridden for another default action.

ULong_t	CheckedHash ()
	Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object.

virtual const char *	ClassName () const
	Returns name of class to which the object belongs.

virtual void	Delete (Option_t *option="")
	Delete this object.

virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object.

virtual void	Draw (Option_t *option="")
	Default Draw method for all objects.

virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs.

virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad with: `gROOT->SetSelectedPad(c1)`.

virtual void	Dump () const
	Dump contents of object on stdout.

virtual void	Error (const char method, const char msgfmt,...) const
	Issue error message.

virtual void	Execute (const char method, const char params, Int_t *error=nullptr)
	Execute method on this object with the given parameter string, e.g.

virtual void	Execute (TMethod method, TObjArray params, Int_t *error=nullptr)
	Execute method on this object with parameters stored in the TObjArray.

virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py).

virtual void	Fatal (const char method, const char msgfmt,...) const
	Issue fatal error message.

virtual TObject *	FindObject (const char *name) const
	Must be redefined in derived classes.

virtual TObject *	FindObject (const TObject *obj) const
	Must be redefined in derived classes.

virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object.

virtual const char *	GetIconName () const
	Returns mime type name of object.

virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py).

virtual Option_t *	GetOption () const

virtual UInt_t	GetUniqueID () const
	Return the unique object id.

virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out.

Bool_t	HasInconsistentHash () const
	Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e.

virtual void	Info (const char method, const char msgfmt,...) const
	Issue info message.

virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname".

virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl.

virtual void	Inspect () const
	Dump contents of this object in a graphics canvas.

void	InvertBit (UInt_t f)

Bool_t	IsDestructed () const
	IsDestructed.

virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory).

virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).

R__ALWAYS_INLINE Bool_t	IsOnHeap () const

R__ALWAYS_INLINE Bool_t	IsZombie () const

void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary).

virtual Bool_t	Notify ()
	This method must be overridden to handle object notification (the base implementation is no-op).

void	Obsolete (const char method, const char asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete.

void	operator delete (void *ptr)
	Operator delete.

void	operator delete[] (void *ptr)
	Operator delete [].

void *	operator new (size_t sz)

void *	operator new (size_t sz, void *vp)

void *	operator new[] (size_t sz)

void *	operator new[] (size_t sz, void *vp)

TObject &	operator= (const TObject &rhs)
	TObject assignment operator.

virtual void	Paint (Option_t *option="")
	This method must be overridden if a class wants to paint itself.

virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list.

virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory.

virtual void	RecursiveRemove (TObject *obj)
	Recursively remove this object from a list.

void	ResetBit (UInt_t f)

virtual void	SaveAs (const char filename="", Option_t option="") const
	Save this object in the file specified by filename.

virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out".

void	SetBit (UInt_t f)

void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f.

virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object.

virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id.

void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

virtual void	SysError (const char method, const char msgfmt,...) const
	Issue system error message.

R__ALWAYS_INLINE Bool_t	TestBit (UInt_t f) const

Int_t	TestBits (UInt_t f) const

virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked.

virtual void	Warning (const char method, const char msgfmt,...) const
	Issue warning message.

virtual Int_t	Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory.

virtual Int_t	Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory.

Public Member Functions inherited from RooPrintable
	RooPrintable ()

virtual	~RooPrintable ()

virtual Int_t	defaultPrintContents (Option_t *opt) const
	Default choice of contents to be printed (name and value)

virtual StyleOption	defaultPrintStyle (Option_t *opt) const

virtual TClass *	IsA () const

virtual void	printAddress (std::ostream &os) const
	Print class name of object.

virtual void	printExtras (std::ostream &os) const
	Interface to print extras of object.

virtual void	printStream (std::ostream &os, Int_t contents, StyleOption style, TString indent="") const
	Print description of object on ostream, printing contents set by contents integer, which is interpreted as an OR of 'enum ContentsOptions' values and in the style given by 'enum StyleOption'.

virtual void	printTree (std::ostream &os, TString indent="") const
	Interface for tree structure printing of object.

virtual void	Streamer (TBuffer &)

void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

Private Member Functions
void	installFormulaOrThrow (const std::string &formulaa)
	Check that the formula compiles, and also fulfills the assumptions.

std::string	processFormula (std::string origFormula) const
	Process given formula by replacing all ordinal and name references by `x[i]`, where `i` matches the position of the argument in `_origList`.

std::string	reconstructFormula (std::string internalRepr) const
	From the internal representation, construct a formula by replacing all index place holders with the names of the variables that are being used to evaluate it.

RooArgList	usedVariables () const
	Analyse internal formula to find out which variables are actually in use.

Private Attributes
std::vector< bool >	_isCategory
	! Whether an element of the _origList is a category.

RooArgList	_origList
	! Original list of dependents

std::unique_ptr< TFormula >	_tFormula
	! The formula used to compute values

Additional Inherited Members
Public Types inherited from TObject
enum	{ kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 , kBitMask = 0x00ffffff }

enum	{ kSingleKey = (1ULL << ( 0 )) , kOverwrite = (1ULL << ( 1 )) , kWriteDelete = (1ULL << ( 2 )) }

enum	EDeprecatedStatusBits { kObjInCanvas = (1ULL << ( 3 )) }

enum	EStatusBits { kCanDelete = (1ULL << ( 0 )) , kMustCleanup = (1ULL << ( 3 )) , kIsReferenced = (1ULL << ( 4 )) , kHasUUID = (1ULL << ( 5 )) , kCannotPick = (1ULL << ( 6 )) , kNoContextMenu = (1ULL << ( 8 )) , kInvalidObject = (1ULL << ( 13 )) }

Public Types inherited from RooPrintable
enum	ContentsOption { kName =1 , kClassName =2 , kValue =4 , kArgs =8 , kExtras =16 , kAddress =32 , kTitle =64 , kCollectionHeader =128 }

enum	StyleOption { kInline =1 , kSingleLine =2 , kStandard =3 , kVerbose =4 , kTreeStructure =5 }

Static Public Member Functions inherited from TNamed
static TClass *	Class ()

static const char *	Class_Name ()

static constexpr Version_t	Class_Version ()

static const char *	DeclFileName ()

Static Public Member Functions inherited from TObject
static TClass *	Class ()

static const char *	Class_Name ()

static constexpr Version_t	Class_Version ()

static const char *	DeclFileName ()

static Longptr_t	GetDtorOnly ()
	Return destructor only flag.

static Bool_t	GetObjectStat ()
	Get status of object stat flag.

static void	SetDtorOnly (void *obj)
	Set destructor only flag.

static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable.

Static Public Member Functions inherited from RooPrintable
static TClass *	Class ()

static const char *	Class_Name ()

static constexpr Version_t	Class_Version ()

static const char *	DeclFileName ()

static std::ostream &	defaultPrintStream (std::ostream *os=nullptr)
	Return a reference to the current default stream to use in Print().

static void	nameFieldLength (Int_t newLen)
	Set length of field reserved from printing name of RooAbsArgs in multi-line collection printing to given amount.

Protected Types inherited from TObject
enum	{ kOnlyPrepStep = (1ULL << ( 3 )) }

Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char location, const char fmt, va_list va) const
	Interface to ErrorHandler (protected).

void	MakeZombie ()

Protected Attributes inherited from TNamed
TString	fName

TString	fTitle

Static Protected Attributes inherited from RooPrintable
static Int_t	_nameLength

#include </home/sftnight/build/workspace/root-makedoc-master/rootspi/rdoc/src/master/roofit/roofitcore/src/RooFormula.h>

Inheritance diagram for RooFormula:

[legend]

Constructor & Destructor Documentation

◆ RooFormula() [1/2]

RooFormula::RooFormula	(	const char *	name,
		const char *	formula,
		const RooArgList &	varList,
		bool	checkVariables = `true`
	)

Construct a new formula.

Parameters

[in]	name	Name of the formula.
[in]	formula	Formula to be evaluated. Parameters/observables are identified by name or ordinal position in `varList`.
[in]	varList	List of variables to be passed to the formula.
[in]	checkVariables	Check that the variables being passed in the `varList` are used in the formula expression.

Definition at line 196 of file RooFormula.cxx.

◆ RooFormula() [2/2]

RooFormula::RooFormula	(	const RooFormula &	other,
		const char *	name = `nullptr`
	)

Copy constructor.

Definition at line 217 of file RooFormula.cxx.

Member Function Documentation

◆ actualDependents()

RooArgSet RooFormula::actualDependents ( ) const

inline

Return list of arguments which are used in the formula.

Definition at line 39 of file RooFormula.h.

◆ changeDependents()

bool RooFormula::changeDependents	(	const RooAbsCollection &	newDeps,
		bool	mustReplaceAll,
		bool	nameChange
	)

Change used variables to those with the same name in given list.

Parameters

[in]	newDeps	New dependents to replace the old ones.
[in]	mustReplaceAll	Will yield an error if one dependent does not have a replacement.
[in]	nameChange	Passed down to RooAbsArg::findNewServer(const RooAbsCollection&, bool) const.

Definition at line 356 of file RooFormula.cxx.

◆ Clone()

TObject * RooFormula::Clone ( const char * newname = nullptr ) const

inlineoverridevirtual

Make a clone of an object using the Streamer facility.

If the object derives from TNamed, this function is called by TNamed::Clone. TNamed::Clone uses the optional argument to set a new name to the newly created object.

If the object class has a DirectoryAutoAdd function, it will be called at the end of the function with the parameter gDirectory. This usually means that the object will be appended to the current ROOT directory.

Reimplemented from TObject.

Definition at line 32 of file RooFormula.h.

◆ doEval()

void RooFormula::doEval ( RooFit::EvalContext & ctx ) const

Definition at line 419 of file RooFormula.cxx.

◆ dump()

void RooFormula::dump ( ) const

DEBUG: Dump state information.

Definition at line 345 of file RooFormula.cxx.

◆ eval()

double RooFormula::eval ( const RooArgSet * nset = nullptr ) const

Evaluate all parameters/observables, and then evaluate formula.

Evaluate the internal TFormula.

First, all variables serving this instance are evaluated given the normalisation set, and then the formula is evaluated.

Parameters

[in] nset Normalisation set passed to evaluation of arguments serving values.

Returns: The result of the evaluation.

Definition at line 394 of file RooFormula.cxx.

◆ formulaString()

std::string RooFormula::formulaString ( ) const

inline

Definition at line 71 of file RooFormula.h.

◆ getParameter() [1/2]

RooAbsArg * RooFormula::getParameter ( const char * name ) const

inline

Return pointer to the parameter with given name.

Returns: Parameter if in use, nullptr if not in use.

Definition at line 44 of file RooFormula.h.

◆ getParameter() [2/2]

RooAbsArg * RooFormula::getParameter ( Int_t index ) const

inline

Return pointer to parameter at given index.

This returns irrespective of whether the parameter is in use.

Definition at line 48 of file RooFormula.h.

◆ getTFormula()

TFormula * RooFormula::getTFormula ( ) const

inline

Definition at line 72 of file RooFormula.h.

◆ installFormulaOrThrow()

void RooFormula::installFormulaOrThrow ( const std::string & formulaa )

private

Check that the formula compiles, and also fulfills the assumptions.

Definition at line 505 of file RooFormula.cxx.

◆ ok()

bool RooFormula::ok ( ) const

inline

Definition at line 50 of file RooFormula.h.

◆ operator=() [1/2]

RooFormula & RooFormula::operator= ( const RooFormula & other )

delete

◆ operator=() [2/2]

RooFormula & RooFormula::operator= ( RooFormula && other )

delete

◆ Print()

void RooFormula::Print ( Option_t * option = nullptr ) const

inlineoverridevirtual

This method must be overridden when a class wants to print itself.

Reimplemented from TObject.

Definition at line 65 of file RooFormula.h.

◆ printArgs()

void RooFormula::printArgs ( std::ostream & os ) const

overridevirtual

Print arguments of formula, i.e. dependents that are actually used.

Reimplemented from RooPrintable.

Definition at line 492 of file RooFormula.cxx.

◆ printClassName()

void RooFormula::printClassName ( std::ostream & os ) const

overridevirtual

Print class name of formula.

Reimplemented from RooPrintable.

Definition at line 483 of file RooFormula.cxx.

◆ printMultiline()

void RooFormula::printMultiline	(	std::ostream &	os,
		Int_t	contents,
		bool	verbose = `false`,
		TString	indent = `""`
	)		const

overridevirtual

Printing interface.

Reimplemented from RooPrintable.

Definition at line 442 of file RooFormula.cxx.

◆ printName()

void RooFormula::printName ( std::ostream & os ) const

overridevirtual

Print name of formula.

Reimplemented from RooPrintable.

Definition at line 465 of file RooFormula.cxx.

◆ printTitle()

void RooFormula::printTitle ( std::ostream & os ) const

overridevirtual

Print title of formula.

Reimplemented from RooPrintable.

Definition at line 474 of file RooFormula.cxx.

◆ printValue()

void RooFormula::printValue ( std::ostream & os ) const

overridevirtual

Print value of formula.

Reimplemented from RooPrintable.

Definition at line 456 of file RooFormula.cxx.

◆ processFormula()

std::string RooFormula::processFormula ( std::string formula ) const

private

Process given formula by replacing all ordinal and name references by x[i], where i matches the position of the argument in _origList.

Further, references to category states such as leptonMulti:one are replaced by the category index.

Definition at line 238 of file RooFormula.cxx.

◆ reconstructFormula()

std::string RooFormula::reconstructFormula ( std::string internalRepr ) const

private

From the internal representation, construct a formula by replacing all index place holders with the names of the variables that are being used to evaluate it.

Definition at line 330 of file RooFormula.cxx.

◆ usedVariables()

RooArgList RooFormula::usedVariables ( ) const

private

Analyse internal formula to find out which variables are actually in use.

Definition at line 300 of file RooFormula.cxx.

Member Data Documentation

◆ _isCategory

std::vector<bool> RooFormula::_isCategory

private

! Whether an element of the _origList is a category.

Definition at line 81 of file RooFormula.h.

◆ _origList

RooArgList RooFormula::_origList

private

! Original list of dependents

Definition at line 80 of file RooFormula.h.

◆ _tFormula

std::unique_ptr<TFormula> RooFormula::_tFormula

private

! The formula used to compute values

Definition at line 82 of file RooFormula.h.

roofit/roofitcore/src/RooFormula.h

roofit/roofitcore/src/RooFormula.cxx

Category expressions

Debugging a formula that won't compile

Public Member Functions

Private Member Functions

Private Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ RooFormula() [1/2]

◆ RooFormula() [2/2]

Member Function Documentation

◆ actualDependents()

◆ changeDependents()

◆ Clone()

◆ doEval()

◆ dump()

◆ eval()

◆ formulaString()

◆ getParameter() [1/2]

◆ getParameter() [2/2]

◆ getTFormula()

◆ installFormulaOrThrow()

◆ ok()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ Print()

◆ printArgs()

◆ printClassName()

◆ printMultiline()

◆ printName()

◆ printTitle()

◆ printValue()

◆ processFormula()

◆ reconstructFormula()

◆ usedVariables()

Member Data Documentation

◆ _isCategory

◆ _origList

◆ _tFormula