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==== Reading Delphes output without ROOT ====

There were questions about how to analyze Delphs3 fast simulation output  if ROOT is not installed (or cannot be installed). Well, better to install it!  But you can also read Delphes data converted to the [[https://atlaswww.hep.anl.gov/asc/promc| ProMC format]] which can be read in any programming language without ROOT.  You can read such files natively using  C++ (without ROOT), Python or Java using Windows, Linux or Mac platforms (or Android, in future). 
You can also use your favorite  IDE, such as Netbeans or Eclipse. 
In this example, we will use plotting library from [[http://jwork.org/scavis|SCaVis]] data-analysis framework, which helps to make histograms, plots and create PDF/EPS figures. 

All Delphes ROOT files, which are listened on [[https://atlaswww.hep.anl.gov/asc/wikidoc/doku.php?id=snowmass2013:montecarlo#monte_carlo_samples_using_the_snowmass_detector| MC fast simulation page]] have been converted to the ProMC format.
For example, every dataset with 96 output ROOT files was converted to a single ProMC file. 
For the current conversion, ProMC files are typically x2-x3 times smaller than all 96 ROOT files combined (partially, due to very efficient compression of ProMC).

Below we will explain how to read such files and fill histograms using Java (you can also use C++ without ROOT, or CPython, since ProMC is fully multiplatform).

==== ProMC file repositories ====

  * [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/?dir=promc| Delphes ProMC file repository]] contains Delphes fast simulation files in the [[https://atlaswww.hep.anl.gov/asc/promc| ProMC format]].  A single file has 96000 Delphes3 events (i.e. corresponds to 96 ROOT files with 1000 events in each). 

  * [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/?dir=promc_truth | ProMC file repository]] contains files with complete truth particle information (all final state particles including pileup particles). See [[snowmass2013:montecarlo_truth| the description]].

You can view truth information in these files using Java (also works on windows):
<code bash>
wget http://atlaswww.hep.anl.gov/asc/promc/download/browser_promc.jar
http://mc.hep.anl.gov/asc/snowmass2013/delphes36/promc/MadGraph5Pythia_wjets/MadGraph5Pythia_wjets_mu0.promc
java -jar browser_promc.jar MadGraph5Pythia_wjets_mu0.promc
</code>
This  brings up a GUI window to look at the stored events. Use Java7 (check as "//java -version//"). Read more about this browser [[asc:promc:examples | here]].
To analyze truth particle information and reconstructed objects (jets, electrons, photons) use the approaches shown below.
==== Reading Delphes data in C++ ====


Here are the steps to analyze data in C++, but without ROOT. Install [[https://atlaswww.hep.anl.gov/asc/promc| ProMC]] library. Then generate analysis code from the ProMC input file and run it:

<code bash>
mkdir test
wget http://mc.hep.anl.gov/asc/snowmass2013/delphes36/promc/MadGraph5Pythia_wjets_mu0.promc
promc_proto # generate layout files in the directory proto
promc_code  # generate analysis code in C++/Java/Python
make        # compiles C++ reader.cc
./reader MadGraph5Pythia_wjets_mu0.promc # read the data 
</code>

==== Reading Delphes data in Java ====
The above example also generates Java code to read the data. Try this:
<code bash>
cd java/
run.sh MadGraph5Pythia_wjets_mu0.promc # read the data 
</code>


==== Reading Delphes data  in Python ====
The above example also generates the Python code to read the ProMC files. Try this:
<code bash>
cd python/
python reader.py  MadGraph5Pythia_wjets_mu0.promc # read the data 
</code>
Look at the "modules" directory to learn about the methods,



===== Reading data using Java without ProMC =====

A more advanced code uses a Java histogramming package, without the ProMC installation:

<code bash>
wget http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read.tgz         # get analysis package
tar -zvxf delphes_read.tgz            # untar it
cd delphes_read                       # go to the analysis directory
wget http://mc.hep.anl.gov/asc/snowmass2013/delphes36/promc/MadGraph5Pythia_wjets/MadGraph5Pythia_wjets_mu0.promc
run.sh   MadGraph5Pythia_wjets_mu0.promc     # compile and run it. 
</code>

It fills a few histograms and show them in a canvas.


==== Browser the truth particle record ====

You can browser the events in the file using the same "lib/browser_promc.jar" file as:

<code>
java -jar lib/browser_promc.jar herwigpp_ttbar_mu0.promc
</code>
It will shows the header file. If you double click on even numbers (left), you will see particle records for a selected event. 

<note tip>
**For Windows:** 
Go to "lib" and double click "browser_promc.jar". 
Open any ProMC file as File->Open ProMC".
</note>


You can setup a NetBeans or Eclipse to identify  all methods for each class (for jets, electrons, muons). Look at the [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.html| Java API of ProMCEvent]] which keeps all Jets, Particles etc. (and their methods). See more info below.
You can also find all methods using Java API included in this example. Read Java API as:

<code>
firefox api/index.html
</code>

Make the needed modifications in the main Java class "ReadProMC.java" to make this example useful for your analysis.

==== Using Python/Jython ====


You can also use Jython (Python implemented in Java), instead of Java, and run the code on any platform (Windows, Mac, Linux). Install [[http://jwork.org/scavis|SCaVis]], and copy an additional jar file "browser_promc.jar" to the ScaVis directory "lib/users". This is how to do this:

<code bash>
cd scavis/lib/user
wget http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/lib/browser_promc.jar
</code>
Restart SCaVis IDE. 

Now you can make  a simple Python script which reads data in the ProMC format:
Here is a small Python/Jython example which plots jet pT. 
Save  this file as "delphes.py" and  open it in the ScaVis IDE. Then press "run".

<file python delphes.py>
# Reading Delphes file in the ProMC format using ScaVis http://jwork.org/scavis
# S.Chekanov (ANL)
from java.io import *
from java.awt import *
from promc.io import *
from proto import *   # import FileMC
from jhplot import *  # import ScaVis graphics

file = FileMC("herwigpp_ttbar_mu0.promc")
version=file.getVersion()
print "ProMC version=",version
header = file.getHeader()
unit=float(header.getMomentumUnit())
lunit=float(header.getLengthUnit())
print "Momentum unit=",unit
print "Length unit=",lunit

h1= H1D("PT (ele)",50,0,1000)   # create a histogram
print "File size=",file.size()
for i in range(file.size()):
      if (i%1000==0): print "Event=",i 
      entry = file.read(i)
      jets = entry.getJets()                   # get jets
      for j in range(jets.getPTCount()): 
            h1.fill(jets.getPT(j)/unit)            
c1 = HPlot("Canvas",600,400) # plot histogram
c1.visible()
c1.setAutoRange()
c1.draw(h1)
c1.export("jetpt.pdf")                          # create PDF file
</file>
You will see a plot of jet pT in a pop-up window. The example uses two classes:

  * [[http://jwork.org/scavis/api/doc.php/jhplot/H1D.html |H1D]] histogram class
  * [[http://jwork.org/scavis/api/doc.php/jhplot/HPlot.html |HPlot]] canvas to show the histogram


Note that we use **unit** (unit for energy) and **lunit** (unit for length) to convert internal (Google's "variant")  representation of ProMC into real numbers representing GeV. Here is the  rule:

  * Energy-related variables, such as E,Mass,PT,and Px,Py,Pz should be divided by **unit**.
  * Length-related based  (X,Y,Z,T)  and Eta and Phi should be divided by   **lunit**. 

We map ROOT branches to Java classes in the  following way:

  * getEvent() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.Event.html | ProMC.ProMCEvent.Event]] class
  * getJets() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.Jets.html | ProMC.PMCEvroent.Jets]] class
  * getGenJets() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.GenJets.html | ProMC.ProMCEvent.GenJets]] class
  * getParticles() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.Particles.html | ProMC.ProMCEvent.Particles]] class
  * getElectrons() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.Electrons.html | ProMC.ProMCEvent.Electrons]] class
  * getMuons() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.Muons.html | ProMC.ProMCEvent.Muons]] class
  * getPhotons() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.Photons.html | ProMC.ProMCEvent.Photons]] class
  * getTracks() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.Tracks.html | ProMC.ProMCEvent.Tracks]] class
  * getBLJets() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.CAJets.html | ProMC.ProMCEvent.CAJets]] class
  * getMissingET() returns [[http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read/api/promc/io/ProMC.ProMCEvent.MissingET.html | ProMC.ProMCEvent.MissingET]] class

Use methods of these classes to access the needed variables.



==== Useful methods ====

As in ROOT, there are a high-level Java classes included to the library 
to manipulate with particles or jets (i.e. similar to TLorenzVector in ROOT).
Look at the Java API of the following classes:

  *  [[http://jwork.org/scavis/api/doc.php/hephysics/particle/LParticle.html | LParticle class]] (or)
  *  [[http://jwork.org/scavis/api/doc.php/hephysics/vec/HepLorentzVector.html | HepLorentzVector class]] 


Some examples using Python (and Java) are shown [[http://jwork.org/scavis/wikidoc/doku.php?id=man:science:physics| here]].

To create [[http://jwork.org/scavis/api/doc.php/hephysics/particle/LParticle.html | LParticle]] from the classes of the ProMC format with viable byte compression, do this:

If you know px,py,pz,and energy in the integer representation from ProMC, simply do this:


<code python>
p=LParticle(px,py,pz,energy)
p.dividePxPyPzE(unit);
</code>
where unit=float(header.getMomentumUnit()) (can be defined at the beginning of this file). This converts integer representation of momenta to the GeV representation. 

If you know PT,Eta,Phi and mass of a jet or other object from the ProMC, create the [[http://jwork.org/scavis/api/doc.php/hephysics/particle/LParticle.html | LParticle]] object as:

<code python>
p=LParticle()
p.setPtEtaPhiM(pt/unit, eta/lunit, phi/lunit, mass/unit);
</code>
Note we use "unit" for pt and mass, while lunit is used for eta and phi.



==== Reading Delphes ProMC files in C++ ====
You can read Delphes ProMC files in C++ (still can be without installing ROOT).
Install [[https://atlaswww.hep.anl.gov/asc/promc| ProMC library]].

<code bash>
wget http://mc.hep.anl.gov/asc/snowmass2013/delphes36/packages/delphes_read_cpp.tgz
tar -zvxf delphes_read_cpp.tgz
cd delphes_read_cpp
wget http://mc.hep.anl.gov/asc/snowmass2013/delphes36/promc/MadGraph5Pythia_wjets_mu0.promc
promc_proto MadGraph5Pythia_wjets_mu0.promc # generates data templates
promc_code                                  # generates source code from the data
make                                        # compiles
delphes_read_cpp MadGraph5Pythia_wjets_mu0.promc
</code>



--- //[[chekanov@anl.gov|Sergei Chekanov]] 2013/04/27 23:02//
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