An RNTuple that is used to read data from storage.

An input ntuple provides data from storage as C++ objects. The ntuple model can be created from the data on storage or it can be imposed by the user. The latter case allows users to read into a specialized ntuple model that covers only a subset of the fields in the ntuple. The ntuple model is used when reading complete entries. Individual fields can be read as well by instantiating a tree view.

Definition at line 90 of file RNTuple.hxx.

Classes
class	RIterator

Public Member Functions
	RNTupleReader (std::unique_ptr< Detail::RPageSource > source)
	The model is generated from the ntuple metadata on storage.

	RNTupleReader (std::unique_ptr< RNTupleModel > model, std::unique_ptr< Detail::RPageSource > source)
	The user imposes an ntuple model, which must be compatible with the model found in the data on storage.

	~RNTupleReader ()

RIterator	begin ()

std::unique_ptr< RNTupleReader >	Clone ()

void	EnableMetrics ()

RIterator	end ()

const RNTupleDescriptor &	GetDescriptor () const

RNTupleGlobalRange	GetEntryRange ()

const Detail::RNTupleMetrics &	GetMetrics () const

RNTupleModel *	GetModel ()

NTupleSize_t	GetNEntries () const

template<typename T >
RNTupleView< T >	GetView (std::string_view fieldName)
	Provides access to an individual field that can contain either a scalar value or a collection, e.g.

RNTupleViewCollection	GetViewCollection (std::string_view fieldName)

void	LoadEntry (NTupleSize_t index)
	Analogous to Fill(), fills the default entry of the model.

void	LoadEntry (NTupleSize_t index, REntry &entry)
	Fills a user provided entry after checking that the entry has been instantiated from the ntuple model.

void	PrintInfo (const ENTupleInfo what=ENTupleInfo::kSummary, std::ostream &output=std::cout)
	Prints a detailed summary of the ntuple, including a list of fields.

void	Show (NTupleSize_t index, const ENTupleShowFormat format=ENTupleShowFormat::kCurrentModelJSON, std::ostream &output=std::cout)
	Shows the values of the i-th entry/row, starting with 0 for the first entry.

Static Public Member Functions
static std::unique_ptr< RNTupleReader >	Open (std::string_view ntupleName, std::string_view storage, const RNTupleReadOptions &options=RNTupleReadOptions())

static std::unique_ptr< RNTupleReader >	Open (std::unique_ptr< RNTupleModel > model, std::string_view ntupleName, std::string_view storage, const RNTupleReadOptions &options=RNTupleReadOptions())

Private Member Functions
void	ConnectModel (const RNTupleModel &model)

RNTupleReader *	GetDisplayReader ()

void	InitPageSource ()

Private Attributes
std::unique_ptr< RNTupleReader >	fDisplayReader
	We use a dedicated on-demand reader for Show() and Scan().

Detail::RNTupleMetrics	fMetrics

std::unique_ptr< RNTupleModel >	fModel
	Needs to be destructed before fSource.

std::unique_ptr< Detail::RPageSource >	fSource

std::unique_ptr< Detail::RPageStorage::RTaskScheduler >	fUnzipTasks
	Set as the page source's scheduler for parallel page decompression if IMT is on Needs to be destructed after the pages source is destructed (an thus be declared before)

#include <ROOT/RNTuple.hxx>

Constructor & Destructor Documentation

◆ RNTupleReader() [1/2]

ROOT::Experimental::RNTupleReader::RNTupleReader	(	std::unique_ptr< RNTupleModel >	model,
		std::unique_ptr< Detail::RPageSource >	source
	)

The user imposes an ntuple model, which must be compatible with the model found in the data on storage.

Definition at line 87 of file RNTuple.cxx.

◆ RNTupleReader() [2/2]

ROOT::Experimental::RNTupleReader::RNTupleReader ( std::unique_ptr< Detail::RPageSource > source )

explicit

The model is generated from the ntuple metadata on storage.

Definition at line 98 of file RNTuple.cxx.

◆ ~RNTupleReader()

ROOT::Experimental::RNTupleReader::~RNTupleReader ( )

default

Member Function Documentation

◆ begin()

RIterator ROOT::Experimental::RNTupleReader::begin ( )

inline

Definition at line 194 of file RNTuple.hxx.

◆ Clone()

std::unique_ptr< RNTupleReader > ROOT::Experimental::RNTupleReader::Clone ( )

inline

Definition at line 147 of file RNTuple.hxx.

◆ ConnectModel()

void ROOT::Experimental::RNTupleReader::ConnectModel ( const RNTupleModel & model )

private

Definition at line 63 of file RNTuple.cxx.

◆ EnableMetrics()

void ROOT::Experimental::RNTupleReader::EnableMetrics ( )

inline

Definition at line 197 of file RNTuple.hxx.

◆ end()

RIterator ROOT::Experimental::RNTupleReader::end ( )

inline

Definition at line 195 of file RNTuple.hxx.

◆ GetDescriptor()

const RNTupleDescriptor & ROOT::Experimental::RNTupleReader::GetDescriptor ( ) const

inline

Definition at line 152 of file RNTuple.hxx.

◆ GetDisplayReader()

ROOT::Experimental::RNTupleReader * ROOT::Experimental::RNTupleReader::GetDisplayReader ( )

private

Definition at line 194 of file RNTuple.cxx.

◆ GetEntryRange()

RNTupleGlobalRange ROOT::Experimental::RNTupleReader::GetEntryRange ( )

inline

Definition at line 179 of file RNTuple.hxx.

◆ GetMetrics()

const Detail::RNTupleMetrics & ROOT::Experimental::RNTupleReader::GetMetrics ( ) const

inline

Definition at line 198 of file RNTuple.hxx.

◆ GetModel()

ROOT::Experimental::RNTupleModel * ROOT::Experimental::RNTupleReader::GetModel ( )

Definition at line 125 of file RNTuple.cxx.

◆ GetNEntries()

NTupleSize_t ROOT::Experimental::RNTupleReader::GetNEntries ( ) const

inline

Definition at line 151 of file RNTuple.hxx.

◆ GetView()

template<typename T >

RNTupleView< T > ROOT::Experimental::RNTupleReader::GetView ( std::string_view fieldName )

inline

Provides access to an individual field that can contain either a scalar value or a collection, e.g.

GetView<double>("particles.pt") or GetView<std::vector<double>>("particle"). It can as well be the index field of a collection itself, like GetView<NTupleSize_t>("particle")

Definition at line 185 of file RNTuple.hxx.

◆ GetViewCollection()

RNTupleViewCollection ROOT::Experimental::RNTupleReader::GetViewCollection ( std::string_view fieldName )

inline

Definition at line 189 of file RNTuple.hxx.

◆ InitPageSource()

void ROOT::Experimental::RNTupleReader::InitPageSource ( )

private

Definition at line 75 of file RNTuple.cxx.

◆ LoadEntry() [1/2]

void ROOT::Experimental::RNTupleReader::LoadEntry ( NTupleSize_t index )

inline

Analogous to Fill(), fills the default entry of the model.

Returns false at the end of the ntuple. On I/O errors, raises an exception.

Definition at line 165 of file RNTuple.hxx.

◆ LoadEntry() [2/2]

void ROOT::Experimental::RNTupleReader::LoadEntry	(	NTupleSize_t	index,
		REntry &	entry
	)

inline

Fills a user provided entry after checking that the entry has been instantiated from the ntuple model.

Definition at line 167 of file RNTuple.hxx.

◆ Open() [1/2]

std::unique_ptr< ROOT::Experimental::RNTupleReader > ROOT::Experimental::RNTupleReader::Open	(	std::string_view	ntupleName,
		std::string_view	storage,
		const RNTupleReadOptions &	options = `RNTupleReadOptions()`
	)

static

Definition at line 117 of file RNTuple.cxx.

◆ Open() [2/2]

std::unique_ptr< ROOT::Experimental::RNTupleReader > ROOT::Experimental::RNTupleReader::Open	(	std::unique_ptr< RNTupleModel >	model,
		std::string_view	ntupleName,
		std::string_view	storage,
		const RNTupleReadOptions &	options = `RNTupleReadOptions()`
	)

static

Definition at line 108 of file RNTuple.cxx.

◆ PrintInfo()

void ROOT::Experimental::RNTupleReader::PrintInfo	(	const ENTupleInfo	what = `ENTupleInfo::kSummary`,
		std::ostream &	output = `std::cout`
	)

Prints a detailed summary of the ntuple, including a list of fields.

Definition at line 134 of file RNTuple.cxx.

◆ Show()

void ROOT::Experimental::RNTupleReader::Show	(	NTupleSize_t	index,
		const ENTupleShowFormat	format = `ENTupleShowFormat::kCurrentModelJSON`,
		std::ostream &	output = `std::cout`
	)

Shows the values of the i-th entry/row, starting with 0 for the first entry.

By default, prints the output in JSON format. Uses the visitor pattern to traverse through each field of the given entry.

Definition at line 202 of file RNTuple.cxx.

Member Data Documentation

◆ fDisplayReader

std::unique_ptr<RNTupleReader> ROOT::Experimental::RNTupleReader::fDisplayReader

private

We use a dedicated on-demand reader for Show() and Scan().

Printing data uses all the fields from the full model even if the analysis code uses only a subset of fields. The display reader is a clone of the original reader.

Definition at line 102 of file RNTuple.hxx.

◆ fMetrics

Detail::RNTupleMetrics ROOT::Experimental::RNTupleReader::fMetrics

private

Definition at line 103 of file RNTuple.hxx.

◆ fModel

std::unique_ptr<RNTupleModel> ROOT::Experimental::RNTupleReader::fModel

private

Needs to be destructed before fSource.

Definition at line 98 of file RNTuple.hxx.

◆ fSource

std::unique_ptr<Detail::RPageSource> ROOT::Experimental::RNTupleReader::fSource

private

Definition at line 96 of file RNTuple.hxx.

◆ fUnzipTasks

std::unique_ptr<Detail::RPageStorage::RTaskScheduler> ROOT::Experimental::RNTupleReader::fUnzipTasks

private

Set as the page source's scheduler for parallel page decompression if IMT is on Needs to be destructed after the pages source is destructed (an thus be declared before)

Definition at line 94 of file RNTuple.hxx.

Libraries for ROOT::Experimental::RNTupleReader:

[legend]

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

tree/ntuple/v7/inc/ROOT/RNTuple.hxx
tree/ntuple/v7/src/RNTuple.cxx

Classes

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Constructor & Destructor Documentation

◆ RNTupleReader() [1/2]

◆ RNTupleReader() [2/2]

◆ ~RNTupleReader()

Member Function Documentation

◆ begin()

◆ Clone()

◆ ConnectModel()

◆ EnableMetrics()

◆ end()

◆ GetDescriptor()

◆ GetDisplayReader()

◆ GetEntryRange()

◆ GetMetrics()

◆ GetModel()

◆ GetNEntries()

◆ GetView()

◆ GetViewCollection()

◆ InitPageSource()

◆ LoadEntry() [1/2]

◆ LoadEntry() [2/2]

◆ Open() [1/2]

◆ Open() [2/2]

◆ PrintInfo()

◆ Show()

Member Data Documentation

◆ fDisplayReader

◆ fMetrics

◆ fModel

◆ fSource

◆ fUnzipTasks