This page collects general ROOT hints. For LHCb specific info see LHCbROOT.

If you are looking for an example containing some specific class (TObjArray below). grep for it in the tutorial directory:

cd $ROOTSYS/tutorials/
grep -r TObjArray *

• Splash Screen - Get rid of the splash screen
• ROOT logon script - How to write a simple script that does useful things when you logon to ROOT.
• How to run ROOT in batch mode

• How to use a chain - How to use chains in ROOT.
• Find the bin the value corresponds to
• Read data from text file - Read the columns of a text file into a root tree.
• Save a plot to a file
• String manipulation - Tips and Tricks for working with strings.

• pyRoot: Constructors - How to use a ROOT constructor with pointers as arguments?
• pyRoot: Passing Lists to TGraph
• pyRoot: Pass by reference
• pyRoot: Ownership in PyROOT - Or how not to loose your canvases.
• pyRoot: Drawing components of pdfs in RooFit - How to draw components of pdf ins RooFit with PyRoot.
• pyRoot: Accessing events in a tree

• Set the number of points to draw a function
• THStack: using and troubleshooting THStack
• TTree::Draw - Tips, Tricks and Pitfalls

• Axis: Set the display range of your axis
• Axis: Set the number of divsions of an axis
• Axis: Configure labels and title
• Axis: Set log scale for an axis
• Axis: Redraw Axis to get ticks on top
• Axis: What does "Bins must be in increasing order mean?"
• Axis: How to format 'Colour Axis' in root
• Marker: Change marker style
• Legend: Adding a legend
• Pads: Change Style of Canvas/Pad - Get rid of grey background and ugly borders.
• Pads: Change the Margins of a pad
• Pads: Pad Layouts - Examples of special Layouts
• StatBox: Draw two stats boxes - How to overlay histograms and draw both stats boxes.
• StatBox: No StatBoxes - Deactivate StatBoxes globally.
• Show cut values as lines or areas
• Improve the color scheme - How to have a nice color scheme

• Root-files - Troubles with root files (e.g. empty files)
• Treatment of non-real numbers / infinity - How to catch infinite and imaginary numbers.

• An easy start to RooFit - Learning the basics about RooFit
• How verbose should RooFit be
• Custom pdfs and workspace - Or how to avoid possible trouble…