ROOT   Reference Guide

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 100 of file RNTuple.hxx.

class  RIterator

## Public Member Functions

The model is generated from the ntuple metadata on storage. More...

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. More...

RIterator begin ()

void EnableMetrics ()

RIterator end ()

const RNTupleDescriptorGetDescriptor () const

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. More...

RNTupleViewCollection GetViewCollection (std::string_view fieldName)

RNTupleGlobalRange GetViewRange ()

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

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

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

Public Member Functions inherited from ROOT::Experimental::Detail::RNTuple
RNTuple (const RNTuple &)=delete

~RNTuple ()

RNTupleModelGetModel ()

RNTupleoperator= (const RNTuple &)=delete

## Static Public Member Functions

static std::unique_ptr< RNTupleReaderOpen (std::string_view ntupleName, std::string_view storage)

static std::unique_ptr< RNTupleReaderOpen (std::unique_ptr< RNTupleModel > model, std::string_view ntupleName, std::string_view storage)

## Private Member Functions

void ConnectModel ()

## Private Attributes

Detail::RNTupleMetrics fMetrics

std::unique_ptr< Detail::RPageSourcefSource

Protected Member Functions inherited from ROOT::Experimental::Detail::RNTuple
RNTuple (std::unique_ptr< RNTupleModel > model)
Only the derived RNTupleReader and RNTupleWriter can be instantiated. More...

Protected Attributes inherited from ROOT::Experimental::Detail::RNTuple
std::unique_ptr< RNTupleModelfModel

NTupleSize_t fNEntries
The number of entries is constant for reading and reflects the sum of Fill() operations when writing. More...

#include <ROOT/RNTuple.hxx>

[legend]

## Constructor & Destructor Documentation

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

Definition at line 58 of file RNTuple.cxx.

explicit

The model is generated from the ntuple metadata on storage.

Definition at line 71 of file RNTuple.cxx.

Definition at line 83 of file RNTuple.cxx.

## ◆ begin()

inline

Definition at line 170 of file RNTuple.hxx.

## ◆ Clone()

inline

Definition at line 136 of file RNTuple.hxx.

## ◆ ConnectModel()

private

Definition at line 46 of file RNTuple.cxx.

## ◆ EnableMetrics()

inline

Definition at line 173 of file RNTuple.hxx.

## ◆ end()

inline

Definition at line 171 of file RNTuple.hxx.

## ◆ GetDescriptor()

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

Definition at line 140 of file RNTuple.hxx.

## ◆ GetNEntries()

inline

Definition at line 139 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 161 of file RNTuple.hxx.

## ◆ GetViewCollection()

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

Definition at line 165 of file RNTuple.hxx.

## ◆ GetViewRange()

inline

Definition at line 155 of file RNTuple.hxx.

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 expection.

Definition at line 147 of file RNTuple.hxx.

inline

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

Definition at line 149 of file RNTuple.hxx.

## ◆ Open() [1/2]

static

Definition at line 97 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 )
static

Definition at line 89 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 104 of file RNTuple.cxx.

## ◆ fMetrics

private

Definition at line 103 of file RNTuple.hxx.