ROOT   6.19/01 Reference Guide
Tree tutorials

Example code which illustrates how to use ROOT trees and ntuples.

Files

file  basic.C
Read data from an ascii file and create a root file with an histogram and an ntuple.

file  basic2.C
Create can ntuple reading data from an ascii file.

file  bill.C
Benchmark comparing row-wise and column-wise storage performance

file  cernbuild.C
Read data (CERN staff) from an ascii file and create a root file with a Tree.

file  cernstaff.C
Playing with a Tree containing variables of type character

file  circular.C
Example of a circular Tree

file  clonesA_Event.C
Example to write & read a Tree built with a complex class inheritance tree.

file  copytree.C
Copy a subset of a Tree to a new Tree

file  copytree2.C
Copy a subset of a Tree to a new Tree, one branch in a separate file.

file  copytree3.C
Example of Root macro to copy a subset of a Tree to a new Tree, selecting entries.

file  drawsparse.C
Convert a THnSparse to a TTree using efficient iteration through the THnSparse and draw a THnSparse using TParallelCoord.

file  h1analysis.C
Example of analysis class for the H1 data.

file  h1analysisProxy.C
Example of analysis class for the H1 data using code generated by MakeProxy.

H1 analysis example expressed in terms of TTreeReader

file  h1chain.C
Creates a TChain to be used by the h1analysis.C class the symbol H1 must point to a directory where the H1 data sets have been installed.

file  hsimpleProxy.C

file  hsimpleProxyDriver.C
This is the driver of the hsimpleProxy example It provides the infrastructure to run that code on an ntuple To be run from the tutorials directory

file  htest.C
Save histograms in Tree branches

file  hvector.C
Write and read STL vectors in a tree.

file  jets.C
Usage of a Tree using the JetEvent class.

file  ntuple1.C
Simple tree analysis.

file  parallelcoord.C
Script illustrating the use of the TParalleCoord class

file  parallelcoordtrans.C
Use of transparency with ||-Coord.

file  printSizes.C
This macro can be used to get aggregate information on the size take on disk or in memory by the various branches in a TTree.

file  run_h1analysis.C
Macro driving the analysis can specify file name and type

file  spider.C
TSpider example.

file  staff.C
Create a plot of the data in cernstaff.root To create cernstaff.root, execute tutorial \$ROOTSYS/tutorials/tree/cernbuild.C

file  tcl.C
How to write a TClonesArray to a TTree

file  temperature.C
This tutorial illustrates how to use the highlight mode with trees.

file  tree.C
Display the Tree data structures

file  tree0.C
Simple Event class example

file  tree1.C
This example is a variant of hsimple.C but using a TTree instead of a TNtuple.

file  tree2.C
This example illustrates how to make a Tree from variables or arrays in a C struct - without a dictionary, by creating the branches for builtin types (int, float, double) and arrays explicitly.

file  tree2a.C
This example is the same as tree2.C, but uses a class instead of a C-struct.

file  tree3.C
Example of a Tree where branches are variable length arrays A second Tree is created and filled in parallel.

file  tree4.C
This example writes a tree with objects of the class Event.

file  treefriend.C
Illustrates how to use Tree friends:

file  treegetval.C
Illustrates how to retrieve TTree variables in arrays.