FWLite Analysis

Complete: 0

WARNING: this twiki is outdated (particularly the use of unnamed macros in fwlite is seriously discouraged, the correct twiki is: WorkBookFWLiteExamples


ROOT can load shared libraries containing the definition of dictionaries that describe the class structure of objects stored in EDM files.

By loading the shared libraries containg class dictionaries, ROOT can invoce object member function, which enriches the possibilities of data inspection in interactive mode.

The shared libraries of objects stored in a EDM file can be loaded automatically using the utility FWLite.

Automatic Library Loading

Automatic library loading can be enabled typing the following command from interactive ROOT prompt:


Those command lines can also invoked every time you start ROOT if you put then a a file called rootlogon.C (se the attached rootlogon.C).

Inspecting Object Methods using FWLite

  • Following the instructions in the bare root section to open a data file and inspect its content via TBrowser. Look at the branch whose name starts with recoTracks_ctfWithMaterialTracks_, select the .obj component, you will see a list of track member functions in addition to the data members accessible from bare root:


  • Double-click on one of the member functions, for instance eta(); you will see in a new window a plot with the distribution of the value returned by the function eta():


The documentation for the class reco::Track can be found in any release under doxygen reference manual:

The list of all members (data and function) is displayd clicking on the "List of all members" link:

Interactive Plots from ROOT Prompt

You can obtain the same plot as above typing the following command from ROOT prompt:

[] Events.Draw("ctfWithMaterialTracks.eta()")

In order to invoke functions from the container object, one has to use the @ character after the branch name. The following will plot the number of tracks in an event:

[] Events.Draw("ctfWithMaterialTracks@.size()")


Finding out the Event Content

Event files are written according to the EDM in different possible data formats, that could even be customized by the user for specific purposes.

In most of the cases, users will find events sample in the following formats:

  • FEVT: Full EVenT, containing all products of event prduction processing, including most of the intermediate processing steps
  • RECO: RECOnstruction output
  • RECOSIM: RECOnstruction output plus selected simulation information (Generator information, Geant tracks and vertices)
  • AOD: Analysis Object Data, a compact subset of RECO format
  • AODSIM: Analysis Object Data plus selected simulation information (Generator information)

Detailed information of the RECO and AOD content are available for every release under the doxygen reference manual under the Data View page. Below the links to the most recent releases:

More Examples

More examples of interactive plots using FWLite can be found in the package:

in the file:


Review Status

Reviewer/Editor and Date (copy from screen) Comments
LucaLista - 16 Oct 2006 page created - expanded from WorkBook tutorial pages
BenediktHegner - 31 Jan 2007 page content last edited
JennyWilliams - 07 Feb 2007 editing to include in SWGuide

Responsible: LucaLista
Last reviewed by: Reviewer

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Topic revision: r14 - 2010-03-08 - SalvatoreRRappoccio

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