IO tutorials

These tutorials illustrate some of the capabilities of the ROOT IO subsystem, including TTree, RNTuple, SQL and XML.

Table of contents

• RNTuple
• TTree
• ROOT File
• Merging multiple ROOT files
• FITS files
• SQL
• XML
• Various I/O related topics

ROOT File

These are the tutorials illustrating the ROOT File and details of its directory-like structure.

Tutorial	Description
file.C	Illustration of the ROOT File description
fildir.C	Illustration of the ROOT File directory-like structure
importCode.C	Create a ROOT File with sub-directories.
readCode.C	Navigate inside a ROOT file with sub-directories and read the objects from each sub-directory.
dirs.C	Create a hierarchy of directories in a ROOT File.
copyFiles.C	Copy all objects (including directories) from a source file.
loopdir.C, loopdir11.C	Loop over all objects of a ROOT file directory and print all the TH1 derived objects in Postscript.

Merging ROOT Files

A few examples and learning material on how to merge ROOT files together.

Tutorial	Description
hadd.C	Macro to add histogram files. NOTE: This macro is kept for didactical purposes only: use instead the executable $ROOTSYS/bin/hadd.
mergeSelective.C	Merge only part of the content of a set of files.
testMergeCont.C	Merge containers.

Various I/O related topics

The following tutorials illustrate various useful ROOT I/O features.

Tutorial		Description
double32.C		Details of the Double32_t data type - what is its precision and how to use it.
float16.C		Details of the Float16_t data type - what is its precision and how to use it.
testTMPIFile.C		Usage of TMPIFile to simulate event reconstruction and merging them in parallel.
	tcontext_context_manager.py	Usage of the TContext class as a Python context manager.
	tfile_context_manager.py	Usage of TFile class as a Python context manager.

Topics
	RNTuple tutorials
	Various examples demonstrating ROOT's RNTuple columnar I/O subsystem.
	TTree tutorials
	Example code which illustrates how to use ROOT trees and ntuples.
	FITS files interface tutorials
	Examples showing the FITS file interface.
	SQL tutorials
	Examples showing the SQL classes.
	XML tutorials
	XML examples.

Files
file	copyFiles.C
	Example of script showing how to copy all objects (including directories) from a source file.
file	dirs.C
	This macro illustrates how to create a hierarchy of directories in a Root file.
file	double32.C
	Tutorial illustrating use and precision of the Double32_t data type You should run this tutorial with ACLIC: a dictionary will be automatically created.
file	fildir.C
	This macro displays the ROOT Directory data structure
file	file.C
	This macro displays the physical ROOT file structure
file	float16.C
	Tutorial illustrating use and precision of the Float16_t data type.
file	hadd.C
	Macro to add histogram files This macro is kept for didactical purposes only: use instead the executable $ROOTSYS/bin/hadd !
file	importCode.C
	Example of script showing how to create a ROOT file with subdirectories.
file	loopdir.C
	Example script to loop over all the objects of a ROOT file directory and print in Postscript all the TH1 derived objects.
file	loopdir11.C
	Example script to loop over all the objects of a ROOT file directory and print in Postscript all the TH1 derived objects.
file	mergeSelective.C
	Merge only part of the content of a set of files.
file	readCode.C
	Example of script showing how to navigate in a ROOT file with sub-directories and read the objects in each sub-directory.
file	tcontext_context_manager.py
	This tutorial demonstrates the usage of the TContext class as a Python context manager.
file	testMergeCont.C
	Macro demonstrating the merging of containers.
file	testTMPIFile.C
	This macro shows the usage of TMPIFile to simulate event reconstruction and merging them in parallel.
file	tfile_context_manager.py
	This tutorial demonstrates the usage of the TFile class as a Python context manager.