This is a class to pass functions from ROOT to R.

TRFunctionExport class

The TRFunctionExport class lets you pass ROOT's functions to R's environment

The next example was based in
https://root.cern/doc/master/NumericalMinimization_8C.html
http://stat.ethz.ch/R-manual/R-devel/library/stats/html/optim.html

Let \( f(x,y)=(x-1)^{2} + 100(y-x^{2})^{2} \) , which is called the Rosenbrock function.

It's known that this function has a minimum when \( y = x^{2}\) , and \( x = 1.\) Let's get the minimum using R's optim package through ROOTR's interface. In the code this function was called "Double_t RosenBrock(const TVectorD xx )", because for optim, the input in your function definition must be a single vector.

The Gradient is formed by

\( \frac{\partial f}{\partial x} = -400x(y - x^{2}) - 2(1 - x) \)

\( \frac{\partial f}{\partial y} = 200(y - x^{2}); \)

The "TVectorD RosenBrockGrad(const TVectorD xx )" function must have a single vector as the argument a it will return a single vetor.

#include<TRInterface.h>
 
//in the next function the pointer *double must be changed by TVectorD, because the pointer has no
//sense in R's environment.
Double_t RosenBrock(const TVectorD xx )
{
  const Double_t x = xx[0];
  const Double_t y = xx[1];
  const Double_t tmp1 = y-x*x;
  const Double_t tmp2 = 1-x;
  return 100*tmp1*tmp1+tmp2*tmp2;
}
 
TVectorD RosenBrockGrad(const TVectorD xx )
{
  const Double_t x = xx[0];
  const Double_t y = xx[1];
  TVectorD grad(2);
  grad[0]=-400 * x * (y - x * x) - 2 * (1 - x);
  grad[1]=200 * (y - x * x);
  return grad;
}
 
 
void Minimization()
{
 ROOT::R::TRInterface &r=ROOT::R::TRInterface::Instance();
 //passing RosenBrock function to R
 r["RosenBrock"]<<ROOT::R::TRFunctionExport(RosenBrock);
 
 //passing RosenBrockGrad function to R
 r["RosenBrockGrad"]<<ROOT::R::TRFunctionExport(RosenBrockGrad);
 
 //the option "method" could be "Nelder-Mead", "BFGS", "CG", "L-BFGS-B", "SANN","Brent"
 //the option "control" lets you put some constraints like:
 //"maxit" The maximum number of iterations
 //"abstol" The absolute convergence tolerance.
 //"reltol" Relative convergence tolerance.
 r<<"result <- optim( c(0.01,0.01), RosenBrock,method='BFGS',control = list(maxit = 1000000) )";
 
 //Getting results from R
 TVectorD  min=r.Eval("result$par");
 
 std::cout.precision(8);
 //printing results
 std::cout<<"-----------------------------------------"<<std::endl;
 std::cout<<"Minimum x="<<min[0]<<" y="<<min[1]<<std::endl;
 std::cout<<"Value at minimum ="<<RosenBrock(min)<<std::endl;
 
 //using the gradient
 r<<"optimHess(result$par, RosenBrock, RosenBrockGrad)";
 r<<"hresult <- optim(c(-1.2,1), RosenBrock, NULL, method = 'BFGS', hessian = TRUE)";
 //getting the minimum calculated with the gradient
 TVectorD  hmin=r.Eval("hresult$par");
 
 //printing results
 std::cout<<"-----------------------------------------"<<std::endl;
 std::cout<<"Minimization with the Gradient"<<endl;
 std::cout<<"Minimum x="<<hmin[0]<<" y="<<hmin[1]<<std::endl;
 std::cout<<"Value at minimum ="<<RosenBrock(hmin)<<std::endl;
 
}

Output

Processing Minimization.C...
-----------------------------------------
Minimum x=0.99980006 y=0.99960016
Value at minimum =3.9974288e-08
-----------------------------------------
Minimization with the Gradient
Minimum x=0.99980443 y=0.99960838
Value at minimum =3.8273828e-08

Users Guide

https://oproject.org/pages/ROOT R Users Guide

Definition at line 140 of file TRFunctionExport.h.

Public Member Functions
	TRFunctionExport ()
	Default TRFunctionExport constructor.

	TRFunctionExport (const TRFunctionExport &fun)
	TRFunctionExport copy constructor.

template<class T >
	TRFunctionExport (T fun)
	TRFunctionExport template constructor that supports a lot of function's prototypes.

	~TRFunctionExport ()
	Default TRFunctionExport destructor.

virtual TClass *	IsA () const

template<class T >
void	SetFunction (T fun)
	function to assign function to export, template method that supports a lot of function's prototypes

virtual void	Streamer (TBuffer &)
	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	Clear (Option_t *="")

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

virtual Int_t	Compare (const TObject *obj) const
	Compare abstract method.

virtual void	Copy (TObject &object) const
	Copy this to obj.

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

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.

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

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

virtual Bool_t	IsSortable () const

R__ALWAYS_INLINE Bool_t	IsZombie () const

virtual void	ls (Option_t *option="") const
	The ls function lists the contents of a class on stdout.

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, void vp)
	Only called by placement new when throwing an exception.

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

void	operator delete[] (void ptr, void vp)
	Only called by placement new[] when throwing an exception.

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

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.

Static Public Member Functions
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.

Protected Attributes
TRInternalFunction *	f

Friends
SEXP	Rcpp::wrap (const TRFunctionExport &f)

class	TRInterface

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 )) }

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 ()

#include <TRFunctionExport.h>

Inheritance diagram for ROOT::R::TRFunctionExport:

[legend]

Constructor & Destructor Documentation

◆ TRFunctionExport() [1/3]

TRFunctionExport::TRFunctionExport ( )

Default TRFunctionExport constructor.

Definition at line 17 of file TRFunctionExport.cxx.

◆ ~TRFunctionExport()

ROOT::R::TRFunctionExport::~TRFunctionExport ( )

inline

Default TRFunctionExport destructor.

Definition at line 154 of file TRFunctionExport.h.

◆ TRFunctionExport() [2/3]

TRFunctionExport::TRFunctionExport ( const TRFunctionExport & fun )

TRFunctionExport copy constructor.

Parameters

fun	other TRFunctionExport

Definition at line 23 of file TRFunctionExport.cxx.

◆ TRFunctionExport() [3/3]

template<class T >

ROOT::R::TRFunctionExport::TRFunctionExport ( T fun )

inline

TRFunctionExport template constructor that supports a lot of function's prototypes.

Parameters

fun	supported function to be wrapped by Rcpp

Definition at line 168 of file TRFunctionExport.h.

Member Function Documentation

◆ Class()

static TClass * ROOT::R::TRFunctionExport::Class ( )

static

Returns: TClass describing this class

◆ Class_Name()

static const char * ROOT::R::TRFunctionExport::Class_Name ( )

static

Returns: Name of this class

◆ Class_Version()

static constexpr Version_t ROOT::R::TRFunctionExport::Class_Version ( )

inlinestaticconstexpr

Returns: Version of this class

Definition at line 183 of file TRFunctionExport.h.

◆ DeclFileName()

static const char * ROOT::R::TRFunctionExport::DeclFileName ( )

inlinestatic

Returns: Name of the file containing the class declaration

Definition at line 183 of file TRFunctionExport.h.

◆ IsA()

virtual TClass * ROOT::R::TRFunctionExport::IsA ( ) const

inlinevirtual

Returns: TClass describing current object

Reimplemented from TObject.

Definition at line 183 of file TRFunctionExport.h.

◆ SetFunction()

template<class T >

void ROOT::R::TRFunctionExport::SetFunction ( T fun )

inline

function to assign function to export, template method that supports a lot of function's prototypes

Parameters

fun	supported function to be wrapped by Rcpp

Definition at line 178 of file TRFunctionExport.h.

◆ Streamer()

virtual void ROOT::R::TRFunctionExport::Streamer ( TBuffer & R__b )

virtual

Stream an object of class TObject.

Reimplemented from TObject.

◆ StreamerNVirtual()

void ROOT::R::TRFunctionExport::StreamerNVirtual ( TBuffer & ClassDef_StreamerNVirtual_b )

inline

Definition at line 183 of file TRFunctionExport.h.

Friends And Related Symbol Documentation

◆ Rcpp::wrap

SEXP Rcpp::wrap ( const TRFunctionExport & f )

friend

◆ TRInterface

friend class TRInterface

friend

Definition at line 141 of file TRFunctionExport.h.

Member Data Documentation

◆ f

TRInternalFunction* ROOT::R::TRFunctionExport::f

protected

Definition at line 144 of file TRFunctionExport.h.

Libraries for ROOT::R::TRFunctionExport:

[legend]

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

bindings/r/inc/TRFunctionExport.h
bindings/r/src/TRFunctionExport.cxx

TRFunctionExport class

Users Guide

Public Member Functions

Static Public Member Functions

Protected Attributes

Friends

Additional Inherited Members

Constructor & Destructor Documentation

◆ TRFunctionExport() [1/3]

◆ ~TRFunctionExport()

◆ TRFunctionExport() [2/3]

◆ TRFunctionExport() [3/3]

Member Function Documentation

◆ Class()

◆ Class_Name()

◆ Class_Version()

◆ DeclFileName()

◆ IsA()

◆ SetFunction()

◆ Streamer()

◆ StreamerNVirtual()

Friends And Related Symbol Documentation

◆ Rcpp::wrap

◆ TRInterface

Member Data Documentation

◆ f