Getting Started

Installation

The RootIO module provides functionality for working with ROOT TTrees in Julia. It allows you to create, manage, and write TTrees to ROOT files using a Julia-friendly API. This guide will walk you through the basic usage of RootIO.

To install the latest version of RootIO.jl, use Julia's package manager by pressing the ] key in the REPL prompt. You should also install ROOT.jl.

julia> ]
pkg> add RootIO
pkg> add ROOT

Basic Methods in RootIO

TTree(file, name, title, rowtype)

Creates a new RootIO TTree, an abstraction over the ROOT TTree, to store rows of the specified type. rowtype must be a composite type. Each field of the composite type will be stored in a dedicated branch named after the field name.

Example:

using RootIO, ROOT
mutable struct Event
    x::Float32
    y::Float32
    z::Float32
    v::StdVector{Float32}
end
Event() = Event(0, 0, 0, StdVector(Float32[]))
f = ROOT.TFile!Open("data.root", "RECREATE")

# Create a RootIO ttree with columns x, y, z and v
tree = RootIO.TTree(f, "mytree", "mytitle", Event)

# Display the tree definition
Print(tree)

Fill(tree, row)

Appends a row to the RootIO TTree.

Example:

# Fill the TTree from previous example with an event e
e = Event()
e.x, e.y, e.z = rand(3)
e.v = StdVector(rand(Float32, 5))
RootIO.Fill(tree, e)

#Display the tree contents
Scan(tree)

Write(tree)

Writes a ROOT TTree to the associated ROOT file. Call this method after filling the entries in the TTree to finalize the writing to disk.

Example:

RootIO.Write(tree)