CMS Data Analysis School Pre-Exercises - First Set

Introduction

Welcome to the first set of CMS Data Analysis School (CMSDAS) pre-exercises. The purpose of these exercises is to become familiar with the basic software tools required to perform physics analysis at the school. Please run and complete these exercises. Questions for each exercise are in red font. Post the answers in the online response form available from the course web area - For CMSDAS@LPC 2016, Fermilab. A large amount of additional information about these exercises is available in the twikis that we reference. Please remember that twikis evolve but aim to provide the best information at any time. If, at any time problems are encountered please e-mail LPC contact CMSDASATLPC@fnal.gov with a detailed description of your problem. The instructors will be happy to help you.

The CMSDAS exercises (pre-exercises as well as exercises during the school) are intended to be as generic as possible. However, CMSDAS is held at different CMS collaborating institutes - e.g Fermilab, INFN Pisa, DESY, NTU Taiwan, Bari, etc. Participants are expected to request and obtain local (at the intended school location) computer accounts well in advance of the school start date, to ensure they will be able to work right away. It is actually very important for participants to use the pre-exercises as a setup tool, so we recommend for everyone to use the laptop they intend to bring with them at the school (in general NO computer/laptop will be provided at the school), and to connect to the local computing resources that will be used for the school. In many cases laptops will need to be registered to be used in the local school network, so please make sure you take care of this aspect too.

For all the users who will not be actually attending a school, but going through the CMS DAS exercises on their own the preferred cluster is lxplus at CERN.

There are four SETS of pre-exercises. As outlined above, if you are going through the pre-exercises in preparation to attending a CMS DAS, we strongly recommend using the laptop you intend to bring to the school and logging into the cluster local to the school. Once you have run in the school local cluster you can also try them out in your local cluster/Tier-2/Tier-3 facilities with the necessary changes (accounts, login, local storage, local batch systems etc). It is assumed that there would be no difference in doing these exercises and the instructions should work the same way on any other cluster that has the CMS computing environment.

For the exercises that will be done during the school, instructions on the those exercises will be found on twikis similarly to the pre-exercises.

Obtain a computer account:

To have a CERN account, please have a look at Get Account at CERN. Obtaining a CERN account can be time-consuming. To expedite the process please ask the relevant institutional team leader to perform the necessary "signing" after the online form has been submitted and received for initial processing by the secretariat. If you do not have a scratch area then look here.

NOTE: If you need account elsewhere, you need to contact your local cluster admins and follow their instructions.

To get accounts at few specific sites like Fermilab and DESY have a look at the link below

• LPC/Fermilab ( For CMSDAS@LPC please read the information at this link! Get your account but also see details on how to log in, mass storage etc. )
• DESY/Germany

• Windows Kerberos at FNAL
• Hints for setting up Cygwin
• In case one is using PuTTy

If you are attending CMSDAS at the LPC, you should do the pre-exercises on the cmslpc cluster using the laptop you intend to bring to the LPC (that you should register for the FNAL network before coming, see link on the left bar of the CMSDAS@LPC2016 indico agenda.

Obtain a Grid Certificate and CMS VO registration

• A Grid Certificate and CMS VO registration will be needed for the next set of exercises. The registration process can be time-consuming (actions by several people are required), so it is important to start it as soon as possible. There are two main requirements which can be simply summarized: A certificate ensures that you are who you claim to be. A registration in the VO recognizes your (identified by your certificate) as a member of CMS. Use the following link for this: Get Your Grid Certificate and CMSVO. Both are needed to submit jobs on the Grid. Make sure you follow any additional instructions for US-CMS users.

Obtain a github account:

Github

• Generic git help can be found at http://git-scm.com/book/.
• github.com specific help can be found at https://help.github.com.
• A 15 minutes, interactive, git tutorial http://try.github.com/levels/1/challenges/1
• A nice video tutorial about git http://www.youtube.com/watch?v=ZDR433b0HJY
• A nice interactive tutorial about branches in git http://pcottle.github.io/learnGitBranching/
• Even more FAQs https://git.wiki.kernel.org/index.php/Git_FAQ

In order to checkout and develop CMS software, you will need a github account, which is free.

• In case you don’t have one already, simply go to: https://github.com/join and follow the instructions to create a new account. Make sure you use a username people can recognize you easily or to specify your real name.
• In case you already have an account you can simply use “the Sign in” dialog and put your username and password. https://github.com/login
• Recommend: make sure you register in github your ssh key.

NOTE: Legend of colors for this tutorial:

GRAY background for the commands to execute  (cut&paste)

GREEN background for the output sample of the executed commands

BLUE background for the configuration files  (cut&paste)

PINK background for the code (EDAnalyzer etc.)  (cut&paste)

Exercise 1 - Cut and Paste

Note: This exercise is designed to run only on lxplus and cmslpc as copies of the scripts are present there. Elsewhere, one can certainly copy the script and try.

Login to your cluster lxplus6 or cmslpc-sl6 or gridui1.pi.infn.it or gridui2.pi.infn.it or nafhh-cms01.desy.de or nafhh-cms02.desy.de or your local cms cluster. If you are preparing for CMSDAS@LPC2016 please know that the cmslpc-sl6 is the cluster you are supposed to use. By now you should have a FNAL account that you can use to get kerberos credential and follow the instructions on how to log in to the LPC cluster.

Please note: in the following

• if you are at lxplus, you can do as shown below.
• if you are at cmslpc, you can copy ( cp) from ~malik, remember you have to copy this file runThisCommand.py!.
• if you are at UPRM, you can copy ( cp) from ~malik/CMSTutorial, remember you have to copy this file runThisCommand.py!.
• if you are using Bari, you can copy the file from /afs/cern.ch/user/n/ndefilip/public/runThisCommand.py
• if you are using KNUT2, you can download the file (see attachments at the end of this page)

As the exercises often require copying and pasting from instruction, we will make sure that you will have no problems. To verify if cut and paste to/from a terminal window works, first copy the script runThisCommand.py as follows

ssh -Y USERNAME@lxplus6.cern.ch
USERNAME@lxplus6.cern.ch's password: 

Enter the password and then do:

cp /afs/cern.ch/cms/Tutorials/TWIKI_DATA/runThisCommand.py .

NOTE: For cmslpc at Fermilab, you could try the below commands:

Show Hide

kinit USERNAME@FNAL.GOV
Password for USERNAME@FNAL.GOV:

Enter the password and then do:

ssh -Y USERNAME@cmslpc-sl6.fnal.gov
cp ~malik/runThisCommand.py .

NOTE: For UPRM at Mayaguez, you could try the below commands:

Show Hide

ssh -Y USERNAME@alpha00.hep.uprm.edu
cp ~malik/CMSTutorial/runThisCommand.py .

and then cut and paste the following and then hit return

./runThisCommand.py "asdf;klasdjf;kakjsdf;akjf;aksdljf;a" "sldjfqewradsfafaw4efaefawefzdxffasdfw4ffawefawe4fawasdffadsfef"

The response should be your username followed by alphanumeric string of characters unique to your username, for example for a user named malik:

success: malik znyvx 

QUESTION 1 - Post the alphanumeric string of characters unique to your username.

If the command is executed without any cut and paste:

somebody@cmslpc11>./runThisCommand.py

the result will likely be:

Error: You must provide the secret key

Pasting incorrectly, the result will likely be:

Error: You didn't paste the correct input string

Running not on cmslpc ( for example locally on a laptop), will result in:

bash: ./runThisCommand.py: No such file or directory

OR:

Unknown user: malik.

Exercise 2 - Simple Edit Exercise

Note: This exercise is designed to run only on lxplus, cmslpc, Pisa, Mayaguez, and Taipei as the scripts are present there. Elsewhere, one can certainly copy the script and try.

Please note: in the following

• if you are at lxplus, you can do as shown below.
• if you are at cmslpc, you can copy ( cp) from ~malik
• if you are at UPRM, you can copy ( cp) from ~malik/CMSTutorial
• if you are using Bari, you can also copy ( cp) from ~ndefilip/public
• if you are using Pisa, you can also copy ( cp) from ~boccali/public
• If you are using Taipei, you can also copy ( cp) from /home/cmsdas/store/user/cmsdas/2012/PreExerciseFirstSet
• if you are at nafhh-cms, you can do as shown below.

The purpose of this exercise is to ensure that the user can edit files.

cp /afs/cern.ch/cms/Tutorials/TWIKI_DATA/editThisCommand.py .

Show Hide

cp ~malik/CMSTutorial/editThisCommand.py .

Then open editThisCommand.py and make sure that the 11th line has # (hash character) as the first character of the line. If not, explicitly change the following three lines:

# Please comment the line below out by adding a '#' to the front of
# the line.
raise RuntimeError, "You need to comment out this line with a #"

to:

# Please comment the line below out by adding a '#' to the front of
# the line.
#raise RuntimeError, "You need to comment out this line with a #"

Save the file and execute the command:

user@cmslpc12> ./editThisCommand.py

If this is successful, the result will be:

success:  malik 0xB888EFD

QUESTION 2 - Paste the line beginning with "success" into the form provided.

If the file has not been successfully edited, an error message will result such as:

Traceback (most recent call last):
  File "./editThisCommand.py", line 11, in ?
    raise RuntimeError, "You need to comment out this line with a #"
RuntimeError: You need to comment out this line with a #

Exercise 3 - Setup a release area CMSSW_7_3_0_pre1

obtain a github account

 
git config --global user.name <First Name> <Last Name>
git config --global user.email <Your-Email-Address>
git config --global user.github <Your-Just-Created-GitHub-Account>
 

Then can you setup a CMSSW release by below:

 
mkdir YOURWORKINGAREA
cd YOURWORKINGAREA
### If you are using csh shell
setenv SCRAM_ARCH slc6_amd64_gcc491 
### If you are using Bash shell
export SCRAM_ARCH=slc6_amd64_gcc491 
cmsrel CMSSW_7_3_0_pre1
cd CMSSW_7_3_0_pre1/src
cmsenv
git cms-init

 

NOTE: For cmslpc at Fermilab, you would need to run few additional commands, hence the above steps would look like following:

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source /cvmfs/cms.cern.ch/cmsset_default.csh #or .sh for bash
cd ~/nobackup
mkdir YOURWORKINGAREA
cd YOURWORKINGAREA
### If you are using csh shell
setenv SCRAM_ARCH slc6_amd64_gcc481 
### If you are using Bash shell
export SCRAM_ARCH=slc6_amd64_gcc481 
cmsrel CMSSW_7_3_0_pre1
cd CMSSW_7_3_0_pre1/src
cmsenv
git cms-init

NOTE: For cmsdas01 and cmsdas02 at Bari, you would need to run few additional commands, hence the above steps would look like following:

Show Hide

source /afs/cern.ch/user/n/ndefilip/public/logincmsdas.sh
cmscvsroot CMSSW
export SCRAM_ARCH=slc6_amd64_gcc481
scram p CMSSW CMSSW_7_3_0_pre1
cd CMSSW_7_3_0_pre1/src
cmsenv

NOTE: For KNUT2 machines in Korea and UPRM machines in Mayaguez, you would need to run few additional commands, hence the above steps would look like following:

Show Hide

source /cvmfs/cms.cern.ch/cmsset_default.sh (or .csh)
### If you are using csh shell
setenv SCRAM_ARCH slc6_amd64_gcc481 
### If you are using Bash shell
export SCRAM_ARCH=slc6_amd64_gcc481 
cmsrel CMSSW_7_3_0_pre1
cd CMSSW_7_3_0_pre1/src
cmsenv

source /afs/pi.infn.it/grid_exp_sw/cms/scripts/setcms.sh (or .csh)
cmscvsroot CMSSW
(once forever: mkdir -p /gpfs/gpfsddn/cms/user/`id`)
cd /gpfs/gpfsddn/cms/user/`id`mkdir YOURWORKINGAREA
cd YOURWORKINGAREA
setenv SCRAM_ARCH slc5_amd64_gcc462
scram p CMSSW CMSSW_5_3_11
cd CMSSW_5_3_11/src
cmsenv

NOTE: In Taipei, you would follow the following steps:

Show Hide

source /home/cmsdas/env.csh
mkdir YOURWORKINGAREA
cd YOURWORKINGAREA
setenv SCRAM_ARCH slc5_amd64_gcc462
scram p CMSSW CMSSW_5_3_11
cd CMSSW_5_3_11/src
cmsenv

NOTE: For nafhh-cms at DESY, you would need to run addtional commands, hence the above steps would look like following:

Show Hide

ini cmssw
export SCRAM_ARCH=slc5_amd64_gcc462
mkdir YOURWORKINGAREA
cd YOURWORKINGAREA
cmsrel CMSSW_5_3_11
cd CMSSW_5_3_11/src
cmsenv

Run the following command:

echo $CMSSW_BASE

QUESTION 3 - Paste the result of executing the above command in the form

Note: The directory YOURWORKINGAREA/CMSSW_7_3_0_pre1/src is called your WORKING DIRECTORY.

Exercise 4 - Find data in the DAS ( Data Aggregation Service)

In this exercise we will locate the MC dataset RelValZMM and the collision dataset /DoubleMu/CMSSW_7_0_6-GR_70_V2_AN1_RelVal_zMu2011A-v1/MINIAOD using the Data Aggregation Service (not to be confused with the Data Analysis School in which you are partaking!). Also remember DAS is an improved (faster) database access service previously known as DBS (Dataset Bookkeeping System).

Go to the url DAS and type in the space provided:

dataset release=CMSSW_7_3_0_pre1 dataset=/RelValZMM*/*CMSSW_7_3_0_pre1*/MINIAOD*

This will search for datasets, processed with release CMSSW_7_3_0_pre1, which is named like /RelValZMM*/*CMSSW_7_3_0_pre1*/MINIAOD*. The syntax for searches is found here, with many useful common search patterns under "CMS Queries".

For this query, hit enter on the dataset name /RelValZMM_13/CMSSW_7_3_0_pre1-PU50ns_PRE_LS172_V16-v1/MINIAODSIM and after a few seconds another page will appear.

QUESTION 4.1 - What is the size of this data set? Click on "Sites" to get a list of sites hosting this data. Is this data at FNAL?

Click on the link "Files" to get a list of the root files in this dataset. One of the files it contains should look like this:

       
'/store/relval/CMSSW_7_3_0_pre1/RelValZMM_13/MINIAODSIM/PU50ns_PRE_LS172_V16-v1/00000/5E363364-FD5E-E411-88D9-02163E0104D0.root'

If you want to know the name of the dataset from the name of a file, one can go to DAS and type dataset file=/store/relval/CMSSW_7_3_0_pre1/RelValZMM_13/MINIAODSIM/PU50ns_PRE_LS172_V16-v1/00000/5E363364-FD5E-E411-88D9-02163E0104D0.root in the command line and hit "Enter".

Now we will locate a collisions dataset skim using the keyword search which is sometimes more convenient if you know the dataset you are looking for. In DAS, type dataset=/DoubleMu/CMSSW_7_0_6-GR_70_V2_AN1_RelVal_zMu2011A-v1/MINIAOD and hit Enter. Answer the following question:

QUESTION 4.2 - What release was this dataset collected in? (If you see more than one release, just answer one)

Having set your CMSSW environment one can also search for the dataset /DoubleMu/CMSSW_7_0_6-GR_70_V2_AN1_RelVal_zMu2011A-v1/MINIAOD by invoking the DAS command in your WORKING DIRECTORY following the directions here (you might have to use -k option like curl -k https://cmsweb.cern.ch/das/cli > das_client.py to get the das_client.py) and clicking on "DAS Command Line Tool". Use your browser to open the "CLI" macro and download it, following the instructions to change the name to das_client.py. Remember to chmod a+x das_client.py. The query we're interested in is:

NOTE: For cmslpc at Fermilab, you would need to init your proxy beforehand:

Show me how to... Hide

voms-proxy-init -q -voms cms

./das_client.py --query="dataset=/DoubleMu/CMSSW_7_0_6-GR_70_V2_AN1_RelVal_zMu2011A-v1/MINIAOD" --format=plain

You will see something like

Show result... Hide result...

./das_client.py --query="dataset=/DoubleMu/CMSSW_7_0_6-GR_70_V2_AN1_RelVal_zMu2011A-v1/MINIAOD | grep dataset.name" --format=plain

Showing 1-10 out of 1 results, for more results use --idx/--limit options

/DoubleMu/CMSSW_7_0_6-GR_70_V2_AN1_RelVal_zMu2011A-v1/MINIAOD

More information about accessing data in the Data Aggregation Service can be found in WorkBookDataSamples

 
      root://eoscms//eos/cms/store/relval/CMSSW_7_3_0_pre1/RelValZMM_13/MINIAODSIM/PU50ns_PRE_LS172_V16-v1/00000/5E363364-FD5E-E411-88D9-02163E0104D0.root?svcClass=default
      

edmDumpEventContent

Next we will use edmDumpEventContent to dump a summary of the products that are contained within the file we're interested in.

• Use edmDumpEventContent to see what class names etc. to use in order to access the objects in the RECO data file located above. If you want to look at a specific object (say, PFJets) then exectue

   
     edmDumpEventContent --all --regex PFJets /afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_Data_706_RECO.root
     

• NOTE: At the LPC, the root files is located on the EOS area for cmsdas which should be accessed using xrootd:

     edmDumpEventContent --all --regex PFJets root://cmsxrootd.fnal.gov//store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_RECO.root
     

• NOTE: At the UPRM, the root files is located on the hadoop area for cmsdas which should be accessed using xrootd:

     edmDumpEventContent --all --regex PFJets /mnt/hadoop/data/store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_RECO.root
     

• NOTE: In KNU, the root files is /cmsdas/data/pre_exercises/Exe1/CMSDataAnaSch_Data_706_RECO.root

   
     edmDumpEventContent --all --regex PFJets /cmsdas/data/pre_exercises/Exe1/CMSDataAnaSch_Data_706_RECO.root
     

• The output of edmDumpEventContent has information divided into four variable width columns. The first column is the C++ class type of the data, the second is module label, the third is product instance label and the fourth is process name. More information is available at Identifying Data in the Event.
  • QUESTION 5.1 - How many modules produce products of type vector ? What are their names?
  • NOTE: Instead of the above, try without the option --regex PFJets . This will dump the entire event content - a file with many lines. For this reason we'll send the output to a file called EdmDumpEventContent.txt with a UNIX pipe command.
    • To do this execute

       edmDumpEventContent /afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_Data_706_RECO.root > EdmDumpEventContent.txt 

    • To do this at the LPC, execute

       edmDumpEventContent root://cmsxrootd.fnal.gov//store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_RECO.root > EdmDumpEventContent.txt 

    • To do this at UPRM, execute

       edmDumpEventContent /mnt/hadoop/data/store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_RECO.root > EdmDumpEventContent.txt 

    • To do this execute in KNU

       edmDumpEventContent /cmsdas/data/pre_exercises/Exe1/CMSDataAnaSch_Data_706_RECO.root > EdmDumpEventContent.txt 

edmProvDump

To aid in understanding the full history of an analysis, the framework accumulates provenance for all data stored in the standard ROOT output files. Using the command edmProvDump one can print out all the tracked parameters used to create the data file. For example, one can see which modules were run and the CMSSW version used to make the RECO file. In executing the command below it is important to follow the instructions carefully, otherwise a large number of warning messages may appear. The ROOT warning messages can be ignored.

• To do this execute

    edmProvDump /afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_Data_706_RECO.root > EdmProvDump.txt 

• To do this at the LPC

  edmProvDump root://cmsxrootd.fnal.gov//store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_RECO.root > EdmProvDump.txt

• To do this at UPRM

  edmProvDump /mnt/hadoop/data/store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_RECO.root > EdmProvDump.txt

• NOTE: EdmProvDump.txt is a very large file of the order of 40000-60000 lines. Open and look at this file and locate Processing History ( about 20-40 lines from the top).
• QUESTION 5.2 - Which version of CMSSW_?_?_? was used to produce the data?

edmEventSize

Finally we will execute edmEventSize to determine the size of different branches in the data file. Further details may be found here: SWGuideEdmEventSize. edmEventSize isn't actually a 'Core' helper function (anyone can slap 'edm' on the front of a program in CMSSW). You can use edmFileUtil to get a PFN from an LFN (as shown above) so you could combine the call

• Execute

   edmEventSize -v `edmFileUtil -d /store/relval/CMSSW_7_3_0_pre1/RelValZMM_13/MINIAODSIM/PU50ns_PRE_LS172_V16-v1/00000/5E363364-FD5E-E411-88D9-02163E0104D0.root` > EdmEventSize.txt 

• Execute at UPRM

   edmEventSize -v `edmFileUtil -d /store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_RECO.root` > EdmEventSize.txt 

• Execute on the KNU cluster

   edmEventSize -v `edmFileUtil -d /cmsdas/data/PreEX_1/CMSDataAnaSch_MiniAODZMM730pre1.root` > EdmEventSize.txt 

• Open and look at file EdmEventSize.txt and locate the line containing the text patJets_slimmedJets__PAT. There are two numbers following this text that measure the plain and the compressed size of this branch.
• QUESTION 5.3 - What are these two numbers?

Exercise 6 - Familiar with MiniAOD Format

Analyzing physics data at CMS is a very complicated task involving multiple steps, sharing of expertise, cross checks, and comparing different analysis. To maximize physics productivity, CMS has developed a new high-level data tier MiniAOD in Spring 2014 to serve the needs of the mainstream physics analyses while keeping a small event size (30-50 kb/event), with easy access to the algorithms developed by Physics Objects Groups (POGs) in the framework of the CMSSW offline software. The production of MiniAODs will be done centrally for common samples. Its goal is to centralize the production of PAT tuple which were used among the Physics Analysis Groups (PAGs) in Run 1. (Information about PAT can be found in SWGuidePAT and in a CMS conference note.) MiniAOD samples will be used in the Run 2 analysis. Hence it is important to know about this tool. More information about MiniAOD can be found in WorkBookMiniAOD.

The main contents of the MiniAOD are:

• High level physics objects (leptons, photons, jets, E_T^miss), with detailed information in order to allow e.g. retuning of identification criteria, saved using PAT dataformats.
  Some preselection requirements are applied on the objects, and objects failing these requirements are either not stored or stored only with a more limited set of information.
  Some high level corrections are applied: L1+L2+L3(+residual) corrections to jets, type1 corrections to E_T^miss.
• The full list of particles reconstructed by the ParticleFlow, though only storing the most basic quantities for each object (4-vector, impact parameter, pdg id, some quality flags), and with reduced numerical precision; these are useful to recompute isolation, or to perform jet substructure studies.
  For charged particles with p_T > 0.9 GeV, more information about the associated track is saved, including the covariance matrix, so that they can be used for b-tagging purposes.
• MC Truth information: a subset of the genParticles enough to describe the hard scattering process, jet flavour information, and final state leptons and photons; GenJets with p_T > 8 GeV are also stored, and so are the other mc summary information (e.g event weight, LHE header, PDF, PU information).
  In addition, all the stable genParticles with mc status code 1 are also saved, to allow reclustering of GenJets with different algorithms and substructure studies.
• Trigger information: MiniAOD contains the trigger bits associated to all paths, and all the trigger objects that have contributed to firing at least one filter within the trigger. In addition, we store all objects reconstructed at L1 and the L1 global trigger summary, and the prescale values of all the triggers.

As a general reminder, you may be working on lxplus and the data sample used in the exercise might become unavailable later and the exercise might not work. To avoid this scenario for the purpose of this exercise, we have made a small set of datafiles from these and copied them to afs area /afs/cern.ch/user/b/benwu/public/CMSDAS/ which anyone with afs mounted can access.

The Z to dimoun MC file /afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_MiniAODZMM730pre1.root is made in CMSSW_7_3_0_pre1 release and the datafile /afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_Data_706_MiniAOD.root made from the collisions dataskim /DoubleMu/CMSSW_7_0_6-GR_70_V2_AN1_RelVal_zMu2011A-v1/MINIAOD.

In the directory YOURWORKINGAREA/CMSSW_7_3_0_pre1/src, try to open the root file /afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_MiniAODZMM730pre1.root

root -l 

On the ROOT prompt type the following:

gSystem->Load("libFWCoreFWLite.so");
AutoLibraryLoader::enable();
gSystem->Load("libDataFormatsFWLite.so");
gROOT->SetStyle ("Plain");
gStyle->SetOptStat(111111);
TBrowser b;

If you are using lxplus:
TFile::Open("/afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_MiniAODZMM730pre1.root");

If you are at the LPC:
TFile *theFile = TFile::Open("root://cmsxrootd-site.fnal.gov///store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_MiniAODZMM730pre1.root");

If you are at the UPRM:
TFile *theFile = TFile::Open("/mnt/hadoop/data/store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_MiniAODZMM730pre1.root");

If you are using KNUT2:
TFile::Open("/cmsdas/data/pre_exercises/Exe1/CMSDataAnaSch_MiniAODZMM730pre1.root");

To be able to use the member functions of a CMSSW data class from within ROOT, a 'dictionary' for that class needs to be available to ROOT. To obtain that dictionary, it is necessary to load the proper library into ROOT. The first three lines of the code above do exactly that. More information is at WorkBookFWLiteExamples. Note that gROOT->SetStyle ("Plain"); sets a plain white background for all the plots in ROOT.

NOTE: If the rootlogon.C is created in the home area, and the above four lines of code are in that file, the dictionary will be obtained, and all the plots will have a white background automatically upon logging in to ROOT.

Now a ROOT browser window opens and looks like this:

Show result... Hide result...

In this window click on ROOT Files on the left menu and now the window looks like this:

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Click CMSDataAnaSch_MiniAODZMM730pre1.root, then Events, then scroll down and click patMuons_slimmedMuons__PAT and then patMuons_cleanPatMuons__PAT.obj. A window appears that looks like this:

Show result... Hide result...

Scroll a long way down the file (not too fast) and click on pt(). A PAT Muon Pt distribution will appear. These muons have been produced in the Z to mumu interactions as the name of the data sample implies.

Show result... Hide result...

QUESTION 6.1 - What is the mean value of the muon pt() for the MC data?

Note: To exit ROOT simply type .q in the command line.

Now open the data file /afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_Data_706_MiniAOD.root. Similarly run the following command, and answer the following question:

 root -l 

On the ROOT prompt type the following:

gSystem->Load("libFWCoreFWLite.so");
AutoLibraryLoader::enable();
gSystem->Load("libDataFormatsFWLite.so");
gROOT->SetStyle ("Plain");
gStyle->SetOptStat(111111);
TBrowser b;

If you are using lxplus:
TFile::Open("/afs/cern.ch/user/b/benwu/public/CMSDAS/CMSDataAnaSch_Data_706_MiniAOD.root");

If you are at the LPC:
TFile *theFile = TFile::Open("root://cmsxrootd-site.fnal.gov///store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_MiniAOD.root");

If you are at UPRM:
TFile *theFile = TFile::Open("/mnt/hadoop/data/store/user/cmsdas/2016/PRE_EXERCISES/CMSDataAnaSch_Data_706_MiniAOD.root");

If you are using KNUT2:
TFile::Open("/cmsdas/data/pre_exercises/Exe1/CMSDataAnaSch_Data_706_MiniAOD.root");

QUESTION 6.2 - What is the mean value of the muon pt() for the collision data?

Link to SWGuideCMSDataAnalysisSchoolPreExerciseSecondSet

Link to SWGuideCMSDataAnalysisSchoolPreExerciseThirdSet

Link to SWGuideCMSDataAnalysisSchoolPreExerciseFourthSet

• runThisCommand.py.txt: python scripts for questions 1 and 2

• editThisCommand.py.txt: python scripts for questions 1 and 2