Ntuple Handling

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Ntuple Handling
Zsolt Molnar CERN IT/API Zsolt.Molnar_at_cern.ch
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Outline

• Ntuple and tag why and how?
• Structure
• Binding and expressions
• What an user sees - example

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Ntuple and Tag
Event
Moment.
Charge
Energy
Mass
Mass
Energy
Reference
Mass
Energy
Reference
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Structure
AIDA_Ntuple For end users (physicist)
AIDA_Tuple For application developers Traditional
approach
NtupleTag For application developers New approach
General ntuple handling
Equally usable
Data access is hidden
Plugin structure
NtupleTag_HepExp Objectivity
NtupleTag_Hbook For dinosaurs
NtupleTag_Future
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Binding

• Allows to concentrate on the analysis
• Ex. no unnecessary index handling
• Independent and general mathematical objects
• If can be stored
• Connected safely in the background
• Optimized for looping
• The typical use of ntuples

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Expressions

• Handled as independent objects
• Ex. mass gt 100, sqrt( pxpx pypy )
• Compiled and loaded on the fly
• Plugins
• Power of compiled and optimized C code
• Even in an interpreted environment
  (Python/Lizard)
• Optimized
• Minimum compilation time
• Maximum reusability without further compilations
• Parameters, one expression for many ntuples, etc.

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Example as summary
ntuple.project( massgt100, sqrt(mass),
histogram )
float mass for( ntuple.begin()
ntuple.isNotEnd() ntuple.next() ) mass
ntuple.getFloat(3) if( mass gt 100 )
histogram.fill( sqrt(mass) )
Quantityltfloatgt mass ntuple.bind( mass, mass
) for( ntuple.begin() ntuple.isNotEnd()
ntuple.next() ) if( mass gt 100 )
histogram.fill( sqrt(mass) )