Multi-dimensional histogram wrapper using boost::histogram for data collection. More...

#include <Acts/Utilities/Histogram.hpp>

Inheritance diagram for Acts::Experimental::Histogram< Dim >:

Public Member Functions
	Histogram (const Histogram &other)=default
	Copy constructor.
	Histogram (Histogram &&other) noexcept=default
	Move constructor.
	Histogram (std::string name, std::string title, const std::array< AxisVariant, Dim > &axes)
	Construct multi-dimensional histogram from axes.
double	binContent (const std::array< int, Dim > &indices) const
	Get the content of a single bin.
double	binError (const std::array< int, Dim > &indices) const
	Get the error of a single bin.
void	fill (const std::array< double, Dim > &values)
	Fill histogram with values.
const BoostHist &	histogram () const
	Direct access to boost::histogram (for converters and tests).
const std::string &	name () const
	Get histogram name.
Histogram &	operator= (const Histogram &other)=default
	Copy assignment operator.
Histogram &	operator= (Histogram &&other) noexcept=default
	Move assignment operator.
void	setBin (const std::array< int, Dim > &indices, double content, double error)
	Set the content and error of a single bin, discarding whatever was there before.
void	setBinContent (const std::array< int, Dim > &indices, double content)
	Set the content of a single bin, discarding whatever was there before.
Histogram< 1 >	sliceLastAxis (const std::array< int, Dim - 1 > &outerBins) const
	Extract the distribution along the last axis at a fixed bin of the other axes.
template<std::integral... Ints> requires (sizeof...(Ints) + 1 == Dim)
Histogram< 1 >	sliceLastAxis (Ints... outerBins) const
	Extract the distribution along the last axis at a fixed bin of the other axes, given as individual bin indices rather than an array.
const std::string &	title () const
	Get histogram title.
double	totalContent () const
	Total content of the histogram's in-range bins.

Static Public Member Functions
static constexpr std::size_t	rank ()
	Get number of dimensions (compile-time constant).

Detailed Description

template<std::size_t Dim>
class Acts::Experimental::Histogram< Dim >

Multi-dimensional histogram wrapper using boost::histogram for data collection.

This class wraps boost::histogram to provide a ROOT-independent histogram implementation with compile-time dimensionality. Every bin carries a content and an error: fill() gives the usual \( \sqrt{N} \) error, while setBin() can write an arbitrary value/error pair, e.g. from a fit.

Template Parameters

Dim	Number of dimensions

Constructor & Destructor Documentation

◆ Histogram() [1/3]

template<std::size_t Dim>

Acts::Experimental::Histogram< Dim >::Histogram	(	std::string	name,
		std::string	title,
		const std::array< AxisVariant, Dim > &	axes )

Construct multi-dimensional histogram from axes.

Parameters

name	Histogram name (for identification and output)
title	Histogram title (for plotting)
axes	Array of axes with binning and metadata

◆ Histogram() [2/3]

template<std::size_t Dim>

Acts::Experimental::Histogram< Dim >::Histogram ( const Histogram< Dim > & other )

default

Copy constructor.

Parameters

other The other histogram to copy from

◆ Histogram() [3/3]

template<std::size_t Dim>

Acts::Experimental::Histogram< Dim >::Histogram ( Histogram< Dim > && other )

defaultnoexcept

Move constructor.

Parameters

other The other histogram to move from

Member Function Documentation

◆ binContent()

template<std::size_t Dim>

double Acts::Experimental::Histogram< Dim >::binContent ( const std::array< int, Dim > & indices ) const

Get the content of a single bin.

Parameters

indices Zero-based bin index per axis, excluding under-/overflow

Returns: The bin content

Remarks: Indices must be in [0, axis.size()) for every axis

◆ binError()

template<std::size_t Dim>

double Acts::Experimental::Histogram< Dim >::binError ( const std::array< int, Dim > & indices ) const

Get the error of a single bin.

Parameters

indices Zero-based bin index per axis, excluding under-/overflow

Returns: The uncertainty on the bin content

Remarks: Indices must be in [0, axis.size()) for every axis

◆ fill()

template<std::size_t Dim>

void Acts::Experimental::Histogram< Dim >::fill ( const std::array< double, Dim > & values )

Fill histogram with values.

Parameters

values Values to fill (one per axis)

◆ histogram()

template<std::size_t Dim>

const BoostHist & Acts::Experimental::Histogram< Dim >::histogram ( ) const

Direct access to boost::histogram (for converters and tests).

Returns: The underlying boost histogram

◆ name()

template<std::size_t Dim>

const std::string & Acts::Experimental::Histogram< Dim >::name ( ) const

Get histogram name.

Returns: The histogram name

◆ operator=() [1/2]

template<std::size_t Dim>

Histogram & Acts::Experimental::Histogram< Dim >::operator= ( const Histogram< Dim > & other )

default

Copy assignment operator.

Parameters

other The other histogram to copy from

Returns: The copied histogram

◆ operator=() [2/2]

template<std::size_t Dim>

Histogram & Acts::Experimental::Histogram< Dim >::operator= ( Histogram< Dim > && other )

defaultnoexcept

Move assignment operator.

Parameters

other The other histogram to move from

Returns: The moved histogram

◆ rank()

template<std::size_t Dim>

constexpr std::size_t Acts::Experimental::Histogram< Dim >::rank ( )

staticconstexpr

Get number of dimensions (compile-time constant).

Returns: The number of dimensions

◆ setBin()

template<std::size_t Dim>

void Acts::Experimental::Histogram< Dim >::setBin	(	const std::array< int, Dim > &	indices,
		double	content,
		double	error )

Set the content and error of a single bin, discarding whatever was there before.

Parameters

indices	Zero-based bin index per axis, excluding under-/overflow
content	The content to store
error	The uncertainty on `content`

Remarks: Indices must be in [0, axis.size()) for every axis

◆ setBinContent()

template<std::size_t Dim>

void Acts::Experimental::Histogram< Dim >::setBinContent	(	const std::array< int, Dim > &	indices,
		double	content )

Set the content of a single bin, discarding whatever was there before.

Parameters

indices	Zero-based bin index per axis, excluding under-/overflow
content	The content to store

Remarks: Indices must be in [0, axis.size()) for every axis; The bin's error is set to \( \sqrt{content} \), matching the error fill() would give a bin with that many entries. Use setBin to set an arbitrary value/error pair instead.

◆ sliceLastAxis() [1/2]

template<std::size_t Dim>

Histogram< 1 > Acts::Experimental::Histogram< Dim >::sliceLastAxis ( const std::array< int, Dim - 1 > & outerBins ) const

Extract the distribution along the last axis at a fixed bin of the other axes.

Equivalent to ROOT's TH2::ProjectionY(name, xBin + 1, xBin + 1) for a 2D histogram, or TH3::ProjectionZ(name, xBin + 1, xBin + 1, yBin + 1, yBin + 1) for a 3D one.

Parameters

outerBins Zero-based bin index for every axis but the last, in axis order

Returns: A 1D histogram over the last axis

Remarks: Every entry of outerBins must be in range for its axis

◆ sliceLastAxis() [2/2]

template<std::size_t Dim>

template<std::integral... Ints>
requires (sizeof...(Ints) + 1 == Dim)

Histogram< 1 > Acts::Experimental::Histogram< Dim >::sliceLastAxis ( Ints... outerBins ) const

Extract the distribution along the last axis at a fixed bin of the other axes, given as individual bin indices rather than an array.

Parameters

outerBins Zero-based bin index for every axis but the last, in axis order

Returns: A 1D histogram over the last axis

Remarks: Every entry of outerBins must be in range for its axis

◆ title()

template<std::size_t Dim>

const std::string & Acts::Experimental::Histogram< Dim >::title ( ) const

Get histogram title.

Returns: The histogram title

◆ totalContent()

template<std::size_t Dim>

double Acts::Experimental::Histogram< Dim >::totalContent ( ) const

Total content of the histogram's in-range bins.

The ROOT-independent equivalent of TH1::GetEntries() on a filled histogram.

Returns: The sum of all in-range bin contents

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

◆ Histogram() [1/3]

◆ Histogram() [2/3]

◆ Histogram() [3/3]

Member Function Documentation

◆ binContent()

◆ binError()

◆ fill()

◆ histogram()

◆ name()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ rank()

◆ setBin()

◆ setBinContent()

◆ sliceLastAxis() [1/2]

◆ sliceLastAxis() [2/2]

◆ title()

◆ totalContent()