template<typename BinContentType>
class ROOT::Experimental::RHistEngine< BinContentType >

A histogram data structure to bin data along multiple dimensions.

Every call to Fill bins the data according to the axis configuration and increments the bin content:

ROOT::Experimental::RHistEngine<int> hist(10, {5, 15});
hist.Fill(8.5);
// hist.GetBinContent(ROOT::Experimental::RBinIndex(3)) will return 1

The class is templated on the bin content type. For counting, as in the example above, it may be an integral type such as int or long. Narrower types such as unsigned char or short are supported, but may overflow due to their limited range and must be used with care. For weighted filling, the bin content type must not be an integral type, but a floating-point type such as float or double, or the special type RBinWithError. Note that float has a limited significand precision of 24 bits.

An object can have arbitrary dimensionality determined at run-time. The axis configuration is passed as a vector of RAxisVariant:

std::vector<ROOT::Experimental::RAxisVariant> axes;
axes.push_back(ROOT::Experimental::RRegularAxis(10, 5, 15));
axes.push_back(ROOT::Experimental::RVariableBinAxis({1, 10, 100, 1000}));
ROOT::Experimental::RHistEngine<int> hist(axes);
// hist.GetNDimensions() will return 2

Warning: This is part of the ROOT 7 prototype! It will change without notice. It might trigger earthquakes. Feedback is welcome!

Definition at line 69 of file RHistEngine.hxx.

Public Member Functions
template<typename... Axes>
	RHistEngine (const RAxisVariant &axis1, const Axes &...axes)
	Construct a histogram engine.

	RHistEngine (const RHistEngine &)=delete
	The copy constructor is deleted.

	RHistEngine (RHistEngine &&)=default
	Efficiently move construct a histogram engine.

	RHistEngine (std::initializer_list< RAxisVariant > axes)
	Construct a histogram engine.

	RHistEngine (std::uint64_t nNormalBins, std::pair< double, double > interval)
	Construct a one-dimensional histogram engine with a regular axis.

	RHistEngine (std::vector< RAxisVariant > axes)
	Construct a histogram engine.

	~RHistEngine ()=default

void	Add (const RHistEngine &other)
	Add all bin contents of another histogram.

void	AddAtomic (const RHistEngine &other)
	Add all bin contents of another histogram using atomic instructions.

void	Clear ()
	Clear all bin contents.

RHistEngine	Clone () const
	Clone this histogram engine.

template<typename... A>
void	Fill (const A &...args)
	Fill an entry into the histogram.

template<typename... A>
void	Fill (const std::tuple< A... > &args)
	Fill an entry into the histogram.

template<typename... A, typename W >
void	Fill (const std::tuple< A... > &args, const W &weight)
	Fill an entry into the histogram with a user-defined weight.

template<typename... A>
void	Fill (const std::tuple< A... > &args, RWeight weight)
	Fill an entry into the histogram with a weight.

template<typename... A>
void	FillAtomic (const A &...args)
	Fill an entry into the histogram using atomic instructions.

template<typename... A>
void	FillAtomic (const std::tuple< A... > &args)
	Fill an entry into the histogram using atomic instructions.

template<typename... A, typename W >
void	FillAtomic (const std::tuple< A... > &args, const W &weight)
	Fill an entry into the histogram with a user-defined weight using atomic instructions.

template<typename... A>
void	FillAtomic (const std::tuple< A... > &args, RWeight weight)
	Fill an entry into the histogram with a weight using atomic instructions.

const std::vector< RAxisVariant > &	GetAxes () const

template<typename... A>
const BinContentType &	GetBinContent (const A &...args) const
	Get the content of a single bin.

template<std::size_t N>
const BinContentType &	GetBinContent (const std::array< RBinIndex, N > &indices) const
	Get the content of a single bin.

std::size_t	GetNDimensions () const

std::uint64_t	GetTotalNBins () const

RHistEngine &	operator= (const RHistEngine &)=delete
	The copy assignment operator is deleted.

RHistEngine &	operator= (RHistEngine &&)=default
	Efficiently move a histogram engine.

void	Scale (double factor)
	Scale all histogram bin contents.

void	Streamer (TBuffer &)
	ROOT Streamer function to throw when trying to store an object of this class.

Static Public Attributes
static constexpr bool	SupportsWeightedFilling = !std::is_integral_v<BinContentType>
	Whether this histogram engine type supports weighted filling.

Private Attributes
Internal::RAxes	fAxes
	The axis configuration for this histogram. Relevant methods are forwarded from the public interface.

std::vector< BinContentType >	fBinContents
	The bin contents for this histogram.

Friends
template<typename T , std::size_t N>
void	Internal::SetBinContent (RHistEngine< T > &, const std::array< RBinIndex, N > &, const T &)

[in]	axis1	the first axis object
[in]	axes	the remaining axis objects

[in]	nNormalBins	the number of normal bins, must be > 0
[in]	interval	the axis interval (lower end inclusive, upper end exclusive)

[in]	args	the arguments for each axis
[in]	weight	the weight for this entry

Public Member Functions

Static Public Attributes

Private Attributes

Friends

Constructor & Destructor Documentation

◆ RHistEngine() [1/6]

◆ RHistEngine() [2/6]

◆ RHistEngine() [3/6]

◆ RHistEngine() [4/6]

◆ RHistEngine() [5/6]

◆ RHistEngine() [6/6]

◆ ~RHistEngine()

Member Function Documentation

◆ Add()

◆ AddAtomic()

◆ Clear()

◆ Clone()

◆ Fill() [1/4]

◆ Fill() [2/4]

◆ Fill() [3/4]

◆ Fill() [4/4]

◆ FillAtomic() [1/4]

◆ FillAtomic() [2/4]

◆ FillAtomic() [3/4]

◆ FillAtomic() [4/4]

◆ GetAxes()

◆ GetBinContent() [1/2]

◆ GetBinContent() [2/2]

◆ GetNDimensions()

◆ GetTotalNBins()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ Scale()

◆ Streamer()

Friends And Related Symbol Documentation

◆ Internal::SetBinContent

Member Data Documentation

◆ fAxes

◆ fBinContents

◆ SupportsWeightedFilling