Difference: DataAnalysis (2 vs. 3)

Revision 329 Oct 2015 - DanielArcaro

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META TOPICPARENT	name="DanielArcaro"

Data Analysis with CMS

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The best place to start with an Analyzer is the SWGuide. The section mkedanlzr will show how to create a skeleton analyzer to then edit. Once created there are three main files to edit. The first is the analyzerName.cc file which has all the analysis code. The next file is the BuildFile that links any outside code to the analyzer. The last is the python ConfFile_cfg.py script which the cmssw code reads to run your analyzer.

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> The CMSSW Unpacker as listed above is a good place to start looking at some source code examples. Another good example is the built in CMSSW analyzers that can be seen here. The amount of code there is quite hard to sort through so here is a fairly simple one under the data formats directory.

Root

Dependencies / Buildfiles

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#include <cmsswtools/unpacker/interface/FedEvent.hh>

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< as if the home directory (or ~/) is CMSSW_#_#_#/src. The same should be done with the source code for the user created libraries like can be seen in the previous example.

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> as if CMSSW_#_#_#/src is the home directory (or ~/). The same should be done with the source code for the user created libraries like can be seen in the previous example.

Another place to look is at the built in libraries source code or even other peoples libraries/analyzers. A good place I have gathered a lot of information from is here. The link has a huge list of both built in analyzer source code and user created libraries plus analyzers. The format used there has worked for current CMSSW version such as 7_4_2.

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Data

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CMSSW Version

This section is for determining what CMSSW version to choose for a specific data file and see the contents of the file. The data files are all root files and can be found using the procedures above. The main tools are the Event Data Model (edm). Entering edm on lxplus and then pressing tab twice will give a list of all the different edm tools. The two ones used more are edmProvDump which provides the CMSSW version used the create the file. This version should be the version you are using to do any of the analysis. The other tool is edmDumpEventContent which gives a list of the type of data contained in the file. This is explained in more detail in the analyzer section.

Another option is to use a built in cmssw analyzer. An easy implementation of one is in this python script. There are two options for analyzers: EventContentAnalyzer and DumpFEDRawDataProduct(source code)**. The content analyzer will be a similar to edmDumpEventContent and the raw data product just prints the raw data in hex.

The edm tools should always work for global root files but may not work for the local ones. For the recent local runs any CMSSW_7_#_# should work fine since the edmProbDump does not work and cannot tell the exact version.

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< This section is for determining what CMSSW version to choose for a specific data file and see the contents of the file. The data files are all root files and can be found using the procedures above. The main tools are the Event Data Model (edm). Entering edm on lxplus and then pressing tab twice will give a list of all the different edm tools. The two ones used more are edmProvDump which provides the CMSSW version used the create the file. This version should be the version you are using to do any of the analysis. The other tool is edmDumpEventContent which gives a list of the type of data contained in the file. This is explained in more detail in the analyzer section.

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> **The source code for DumpFEDRawDataProduct is a pretty simple one page analyzer because if only prints some data to screen so it is a very good reference. The site also provides pretty much all the source code for the analyzers. It may be quite complicated but very useful.

Analysis

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