CMSSWCheatSheet < Main

Main Web>TWikiUsers>HalilGamsizkan>CMSSWCheatSheet (2016-07-05, HalilGamsizkan) (raw view)
---+ Cheatsheet: [[CMS.WorkBook][CMSSW]] Analysis a la Framework 
An unofficial information dump page for CMSSW. In below there's older and newer information together, I tried to separate them whenever I can.

[[CMSPublic.WorkBook][CMSSW]]

%TOC%
---++Accessing physics objects

---+++Electrons (PAT/MiniAOD)
|Wiki pages|CMSPublic.WorkBookPATDataFormats#PatElectron, CMSPublic.WorkBookElectronAnalysis |
|Add to buildfile|=&lt;use name="DataFormats/PatCandidates"/&gt;=| Related error: =undefined reference to `pat::Electron::electronID(std::string const&) const=|
|Header file(s)|=#include &lt;DataFormats/PatCandidates/interface/Electron.h&gt;=|
|Label|=slimmedElectrons=|
|Collection type| =pat::ElectronCollection= (=vector&lt;pat::Electron&gt;=)|
|Object reference| [[https://cmssdt.cern.ch/SDT/doxygen/CMSSW_5_3_14/doc/html/d2/d1f/classpat_1_1Electron.html][link]]|
|Notes|To see available electron IDs in data, type a wrong ID name in the =electronID=  method and framework will list them along with the error message.|


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---+++ Generator Particles
|Wiki page|CMS.WorkBookGenParticleCandidate|
|Add to buildfile|=&lt;use name=SimDataFormats/HepMCProduct&gt;=|
|Header file(s)| =#include "DataFormats/Candidate/interface/Candidate.h"= and %BR% =#include "DataFormats/JetReco/interface/GenJet.h"= if you need GEN jets|
|Label|=genParticleCandidates=|
|Collection type|=CandidateCollection=|
|Physics Object| =[[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/d6/de9/classreco_1_1Candidate-members.html][Candidate]]= %BR% [[http://projects.hepforge.org/rivet/code/hepmc/classHepMC_1_1GenParticle.html][GenParticle]]|



---+++Electrons
|Wiki page|CMS.WorkBookElectronReco|
|Add to buildfile|=&lt;use name=DataFormats/EgammaReco&gt;=|
|Header file(s)|=#include "DataFormats/EgammaCandidates/interface/PixelMatchGsfElectron.h"=|
|Label|=pixelMatchGsfElectrons=|
|Collection type|=PixelMatchGsfElectronCollection=|
|Physics Object| [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/d3/d30/classreco_1_1PixelMatchGsfElectron-members.html][PixelMatchGsfElectron]]|

---+++Photons
|Wiki page|CMS.WorkBookPhotonReco|
|Add to buildfile|=&lt;use name=DataFormats/EgammaReco&gt;=|
|Header file(s)|=#include "DataFormats/EgammaCandidates/interface/Photon.h"=|
|Label|=correctedPhotons= or =photons=|
|Collection type|=PhotonCollection=|
|Physics object|[[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/da/da0/classreco_1_1Photon-members.html][reco::Photon]]|

---+++Jets
|Wiki page|CMS.WorkBookJetAnalysis|
|Add to buildfile|=&lt;use name=DataFormats/JetReco&gt;=|
|Header file(s)|=#include "DataFormats/JetReco/interface/CaloJet.h"= %BR% =#include "DataFormats/JetReco/interface/GenJet.h"=|
|Label|Many, e.g. =iterativeCone5CaloJets= %BR% =midPointCone5GenJets=|
|Collection type|=CaloJetCollection= %BR% =GenJetCollection=|
|Physics object|[[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/d9/d5a/classreco_1_1Jet-members.html][reco::Jet]]|

---+++Muons
|Wiki page|CMS.WorkBookMuonAnalysis|
|Add to buildfile|=&lt;use name=DataFormats/MuonReco&gt;= %BR% =&lt;use name=RecoMuon/TrackingTools&gt;=|
|Header file(s)|=#include "DataFormats/MuonReco/interface/Muon.h"=|
|Label|=muons=|
|Collection type|=MuonCollection=|
| Physics Object | [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_nightly/doc/html/d4/da2/classreco_1_1Muon-members.html][reco::Muon]]|
|Example code| [[http://cmssw.cvs.cern.ch/cgi-bin/cmssw.cgi/CMSSW/RecoMuon/GlobalMuonProducer/test/][available]]|
See [[https://hypernews.cern.ch/HyperNews/CMS/get/famos/79/1.html][this hypernews thread]] for the muons with fast simulation.

---+++MET
|Wiki page| ??? |
|Add to buildfile|=&lt;use name=DataFormats/METReco&gt;=|
|Header file(s)|[[http://cmslxr.fnal.gov/lxr/source/DataFormats/METReco/interface/CaloMETCollection.h][#include "DataFormats/METReco/interface/CaloMETCollection.h"]]|
|Label|=met=|
|Collection type|=CaloMETCollection=|
| Physics Object | [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/d5/d85/classreco_1_1CaloMET.html][reco::CaloMET]] |
|Example code| Below, or in [[http://cmslxr.fnal.gov/lxr/source/ElectroWeakAnalysis/ZTauTau_DoubleTauJet/src/EWKTauAnalyser.cc#755][SusyAnalyzer]] |
|Other | <verbatim>
Handle<CaloMETCollection> met;
iEvent.getByLabel("met", met);
const CaloMET calomet = met->front();
cout << "met px=" << calomet.px() << ", py=" << calomet.py() << endl; </verbatim>|


---+++Vertices
|Wiki page|CMS.WorkBookOfflinePrimaryVertexFinding|
|Add to buildfile| ??? |
|Header file(s)| =#include <DataFormats/VertexReco/interface/Vertex.h>= %BR% =#include <DataFormats/VertexReco/interface/VertexFwd.h>= |
|Label|=offlinePrimaryVerticesFromCTFTracks= and =offlinePrimaryVerticesFromRSTracks=|
|Collection type|[[http://cmslxr.fnal.gov/lxr/source/DataFormats/VertexReco/interface/VertexFwd.h#011][VertexCollection]]|
|Physics object | [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/da/d95/classreco_1_1Vertex.html][reco::Vertex]] |
|Example code||

---+++ Tracks
| Physics Object | [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/dd/d5b/classreco_1_1Track.html][reco::Track]]|


---+++ !CaloTowers
These are combined objects from ECAL cells and HCAL towers, they represent the whole calorimetry and are used for e.g. jet reconstruction.
|Wiki page||
|Header file(s)|[[http://cmslxr.fnal.gov/lxr/source/DataFormats/CaloTowers/interface/CaloTowerCollection.h][#include "DataFormats/CaloTowers/interface/CaloTowerCollection.h"]]|
|Label|=towerMaker=|
|Collection type|=CaloTowerCollection=|
|Physics object | [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/d4/d06/classCaloTower-members.html][CaloTower]]|
|Example code||
|Info|[[https://twiki.cern.ch/twiki/bin/view/CMS/WorkBook130JetAnalysis#CaloTower][1]]|


<!--
---+++L1/HLT Trigger
|Wiki page|CMS.WorkBook.WorkBookHLTTutorial|
|Add to buildfile|=&lt;use name=HLTrigger/HLTcore&gt;=%BR% =&lt;use name=DataFormats/HLTReco&gt;=%BR% =&lt;use name=DataFormats/L1GlobalTrigger&gt;= %BR% =&lt;use name=DataFormats/L1Trigger&gt;=|
|Header file(s)|=#include "HLTrigger/HLTanalyzers/interface/HLTInfo.h"=, =#include "DataFormats/Common/interface/TriggerResults.h"=|
|Label|=TriggerResults=|
|Collection type|[[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/de/d3a/classedm_1_1TriggerResults-members.html][TriggerResults]]|
| Physics Object | ??? |
|Example code| |



-->

   * More labels, collections and documentation available [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideDataFormatTable][here]].
   * Namespace documentations: [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/d1/d57/namespacereco.html][reco]], [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/da/d1f/namespaceedm.html][edm]].

%ENDTWISTY%


---+++ "Handling" the data

[[CMSPublic.SWGuideEDMGetDataFromEvent][Main article]]

One accesses the data in the root file thru "handles". Handles types are templated with the collection/data type in the EDM root file. =EdmDumpEvent= prints the collection types in the first column of it's output.

In the class definition, define as private the token<verbatim>
edm::EDGetTokenT< pat::ElectronCollection > tok_electrons_;</verbatim>
In the constructor assign it's value<verbatim>
std::string labelElec_("slimmedElectrons");
tok_electrons_ = consumes< pat::ElectronCollection >(edm::InputTag(labelElec_));</verbatim>
In the analysis code, handle it<verbatim>
Handle<pat::ElectronCollection> elec;
iEvent.getByToken( tok_electrons_, elec );</verbatim>

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Taken from [[https://twiki.cern.ch/twiki/bin/viewfile/CMS/May07PhysicsDaysTutorials?rev=1;filename=TutorialCERN0507dataformats.pdf][Benedikt's presentation]]:<verbatim>
# by module and default product label
Handle<TrackVector> trackPtr;
iEvent.getByLabel("tracker", trackPtr );

# by module and product label
Handle<MuonCollection>trackPtr;
string muonModule_ = "paramMuons"
string muonProduct_ = "ParamGlobalMuons"
iEvent.getByLabel(muonModule_, muonProduct_, muons);

# by type (what happens if not unique?)
vector<Handle<SimHitVector> > allPtr;
iEvent.getByType( allPtr );

# by Selector
ParameterSelector<int> coneSel("coneSize",5);
Handle<JetVector> jetPtr;
iEvent.get( coneSel, jetPtr );</verbatim>
%ENDTWISTY%

---+++ Looping over particles
Handle types are =edm::Handle&lt;CollectionType&gt;=  and collection types are usually =std::vector&lt;ObjectType&gt;=. 

if your product contains objects of type =ObjectType=, contained in collection of type =CollectionType= , and handled by the _variable_ =theHandle=:
<verbatim>
   for (size_t j = 0; j < theHandle->size(); ++ j ) {
      const ObjectType & particle = (*theHandle)[ j ];
      cout << "->   electron" << j << " pT: " << particle.pt() 
            << " eta: " << particle.eta() 
            << " phi: " << particle.phi() << endl;
      someHisto ->Fill( particle.pt() ); 
   };
</verbatim> Yet another loop using an iterator<verbatim>
   size_t idx = 0;
   for( CollectionType::const_iterator cand = theHandle->begin(); 
         cand != theHandle->end(); ++ cand, ++ idx ) {
         // do something, cand is a pointer to your object
         cout << "Electron #" << idx << ": pt=" << cand->pt() << endl;      
   }</verbatim>

---++Code snippets/recipes
---+++Filtering events according to hlt path
This goes to the cfg file:<verbatim>
   include "HLTrigger/HLTfilters/data/hltHighLevel.cfi"                                                                                                                           
   replace hltHighLevel.HLTPaths = {"CandHLT1SumET"}
</verbatim>
---+++Sending a string to your analysis module from cfg file
Let's send a filename to our analysis class. Your cfg file should look like zis:<verbatim>
   module somename = YourAnalysisClass {    
      ...
      untracked string fname = "somefile.root"
      ...
   }</verbatim>and the header of your analysis class:<verbatim>
class YourAnalysisClass : public edm::EDAnalyzer{
   ...
   private:
      ...
      std::string fname_;
      ...
</verbatim>finally the analysis class constructor:<verbatim>
YourAnalysisClass::YourAnalysisClass(const edm::ParameterSet& cfg):
   fname_ ( cfg.getUntrackedParameter<string>( "fname" ) ) ,
   <further parameters received here> {
... constructor code here... }</verbatim>Alternative way to receive parameters from within constructor: <verbatim>
YourAnalysisClass::YourAnalysisClass(const edm::ParameterSet& cfg){
   fname =  cfg.getUntrackedParameter<string>( "fname" );
   ... More constructor code/further parameter receiving code here.. }
</verbatim>More information about other types is [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideAboutConfigFile#Parameters][here]]. Info about cfg files is [[CMS.WorkBookConfigFileIntro][here]].

---++ Is a parameter provided in the cfg file?
<verbatim>
MyAnalyzer::MyAnalyzer(const edm::ParameterSet &conf) {
    if (conf.exists("some_parameter")) do_something</verbatim>

---++ Does a certain product exist in your root file?
<verbatim>  Handle<L1GlobalTriggerReadoutRecord> L1GTRR;
  try {iEvent.getByLabel(l1GTReadoutRecTag_,L1GTRR);} catch (...) {;}
  if ( L1GTRR.isValid() ) { // exists</verbatim>or<verbatim>
edm::Handle<edm::TriggerResults> trh;
try {iEvent.getByLabel(triggerInputTag_,trh);} 
catch( cms::Exception& ex ) { LogWarning("HWWTreeDumper") << "Trigger results: " << triggerInputTag_ << " not found"; }
if (!trh.isValid())
   throw cms::Exception("ProductNotValid") << "TriggerResults product not valid";</verbatim>

---++ Setting the event generator random number seed
Implementation in the =cfg= file is:<verbatim>
service =  RandomNumberGeneratorService {
   # This is to initialize the random engine of the source
    untracked uint32 sourceSeed = 123456789
}</verbatim>

---++ Arsenal
There are numerous [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuidePhysicsTools][useful tools]] available for analyses. Using these tools will usually result in shorter code, and more reliable results; and the most important,  If some of your results are just not OK, you can blame the developers on it :)
   * [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideCandidateModules#Candidate_Selectors][Candidate selectors]] allow you to preselect physics objects on the fly, right within the =cfg= file.
   * [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideCandidateModules#ParticleTreeDrawer_Utility][Gen decay tree analysis modules]], [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideCandidateModules#ParticleListDrawer_Utility][ParticleListDrawer_Utility]]
   * [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideCandCombiner#CandCombiner_Framework_Modules][Candidate combiner]] reconstructs decayed particles (e.g. mu+mu- -&gt; Z).
   * [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideCandidateModules#Candidate_Matching_Modules][Various matching modules]]
   * [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideGenericIsolation][Isolation]] stuff.
   * Modules for [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideCommonFilterModules][filtering events]].
   * [[CMS.SWGuideCommonMathFunctions][Common math functions]]
---++ Locating/Accessing Datasets
   1 To [[https://twiki.cern.ch/twiki/bin/view/CMS/WorkBookSetComputerNode#OpenCastorFiles][access root files from CMSSW]], use the following format:<verbatim>
source = PoolSource{ 
   untracked vstring fileNames = {'rfio:/castor/cern.ch/path/to/someData.root', 'another file', ... }  
} </verbatim> Here the =rfio:= prefix means that the file is on CASTOR. For a local file, use the =file:= prefix.
   1 Now let's locate where the data is. Browse to the [[http://cmsdbs.cern.ch/DBS2_discovery/][DBS Dataset Discovery Page]] and search for the dataset of your interest.
   1 Once you find your dataset, check it's location. If located at =srm.cern.ch= , then you can access it directly from =lxplus= since it's on CASTOR. Click "plain". You'll see a long list of root files in the form:<verbatim>
/store/mc/year/month/day/<~dataset name>/<some number>/longnamedfile.root</verbatim> This path translates to CASTOR location =/castor/cern.ch/cms/&lt;location&gt;=. You can pick e.g. individual files this way. ( ="rfio:/castor/cern.ch/cms/store/RelVal/.../somedata.root"=  or ="/store/RelVal/.../somedata.root"= ). 
   1 If you want to access the whoel dataset, click "cff" instead of "plain" on dataset's page. This will show you a =cff= file containing paths and names of all root files belonging to that dataset. Directly include this =cff= file in your =cfg= file.
   1 Hint: While working on a single root file which is on CASTOR, copying it to =/tmp/$USER= and then accessing from there may speed up things.
---++Framework messages to file
<verbatim>    # Keep the logging output to a nice level #
    include "FWCore/MessageService/data/MessageLogger.cfi"
    replace MessageLogger.destinations = {"detailedInfo.txt"}</verbatim>
---++Other possibly useful stuff
   * Event selection using trigger-HLT bits: [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideHighLevelTrigger#Event_selection_using_trigger_bi][here]].
   * Skipping missing input root files (goes into the [[CMS.SWGuideEDMParametersForModules#PoolSource][PoolSource part]]):<verbatim>
untracked bool skipBadFiles = true #  skip missing or inaccessible files. Defaults to false</verbatim> Note that this won't prevent crashes with bad root files.
   * Skipping the first _n_ events in a root file:<verbatim>
   source = PoolSource {
      untracked vstring fileNames = { <empty or list of files> }
      untracked uint32 skipEvents  = 21
   }</verbatim> Skips the _first 21_ events. Note that the =FirstEvent= / =FirstRun= options may not work the same way.
   * Throwing exceptions
<verbatim>
    throw cms::Exception("ErrorName") << "Message";</verbatim> FIXME: Add header
   * [[CMSPublic.SWGuideSkeletonCodeGenerator][Skeleton code generators]] are very useful.
   * Getting the cross-section of the generated event:<verbatim>
 Handle<double> genCrossSect;
 evt.getByLabel( "genEventRunInfo:PreCalculatedCrossSection", genCrossSect);</verbatim>
   * Useful tool: [[https://twiki.cern.ch/twiki/bin/view/CMS/CMSSWUserTools#addpkg_pl][addpkg]] , checks out packages from CVS.
   * List of [[http://cmssw.cvs.cern.ch/cgi-bin/cmssw.cgi/CMSSW/PhysicsTools/RecoCandAlgos/plugins/][candidate clone producers]]. 
   * List of clone producers immediately available as [[http://cmssw.cvs.cern.ch/cgi-bin/cmssw.cgi/CMSSW/PhysicsTools/RecoCandAlgos/data/][modules]].
   * CMSSW location on AFS (=cern.ch=): =/afs/cern.ch/cms/sw/slc4_ia32_gcc345/cms/cmssw/CMSSW_X_Y_Z=, 
   * Other interesting locations on AFS (header files):
      * =$CMSSW_ROOT/src/DataFormats/Candidate/interface=
      * =$CMSSW_ROOT/src/DataFormats/Math/interface=
   *  [[https://twiki.cern.ch/twiki/bin/view/CMS/SWGuideEDProducerAnalysis#Saving_a_Subsample_of_the_AOD_pl][Saving a Subsample of the   AOD plus the User Data]]
   * See which physics objects a root file contains: =EdmDumpEventContent &lt;root file&gt;=
   * =scramv1 p= is the shorthand for =scramv1 project= . Other shorthands: =r= for =runtime= , =s= for =setup=
   * I don't know what exactly =scramv1 b --fast= does but I think unless you do not change your buildfiles and add/remove new source files it's safe to use this option which speeds up the compile.

---++ Dropping Products
Put into =PoolSource= module block<verbatim>
untracked vstring outputCommands = 
  {
    "keep *",
    "drop *_*_*_HLT",
    "keep FEDRawDataCollection_*_*_*"
  }
</verbatim>More info available [[CMS.SWGuideSelectingBranchesForOutput][here]].

---++ Keeping Products
<verbatim>
untracked vstring outputCommands = {    
     "drop *",
    # HepMC event. Famos uses it
     "keep edmHepMCProduct_source_*_*",
     "keep edmGenInfoProduct_source_*_*",

    # or
    "keep *_source_*_*",

   # Old gen event format
    "keep *_genParticleCandidates_*_*",

    # New gen event format
    "keep *_genParticles_*_*",          # to be removed when no external MC ref's left

   # Keep trigger results
    "keep edmTriggerResults_TriggerResults_*_*",

    # if you chose to save all particles into a  collection in PAT layer0, to make it persistent
    "keep *_*_allJets_*", 

   # Gen jets
    "keep *_midPointCone5GenJetsNoNuBSM_*_*",

   # Calo towers
   "keep *_towerMaker_*_*",

    # CSA07 Stuff
    "keep *_genEventWeight_*_*",
    "keep *_genEventScale_*_*",
    "keep *_genEventProcID_*_*",
    "keep *_csa07EventWeightProducer_*_*"}</verbatim>

---++Notes
   * Keep your buildfiles as clean as possible. Smaller buildfiles, faster compiles.

---++ Useful Links Dump
   * [[CMS.WorkBookWhichRelease][Which CMSSW version to go?]]
   * [[CMS.TriggerTables][Trigger Tables, HLT, L1, Menu]]
   * [[CMS.SWGuideEDMParametersForModules][Module cfg file parameters]]
   * [[http://cmsdoc.cern.ch/Releases/CMSSW/latest_release/doc/html/index.html][CMSSW reference manual]]
   * [[http://cmssw.cvs.cern.ch/cgi-bin/cmssw.cgi/CMSSW/][CMSSW CVS (source) code browser]]
   * [[http://cmslxr.fnal.gov/lxr/][CMSSW CVS search facility]] (LXR)
   * [[CMS.CMSSW_aptinstaller][Installing CMSSW with apt-get]]
   * [[http://uncyclopedia.org/wiki/UnNews:Ask_Cthulhu/100407][Cthulhu]] is always there to help you with your whatever problems!

%REVINFO%
Topic revision: r54 - 2016-07-05 - HalilGamsizkan
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