PhysicsTools/PythonAnalysis/doc/PythonAnalysis.doc - master - githubmirror/cmssw

PhysicsTools/PythonAnalysis/doc/PythonAnalysis.doc
95 строк3 KB
Giulio Eulisse
Snapshot of CMSSW_6_2_0_pre8.
26 июн 2013, 18:12
26 июн 2013, 18:12214ab73
/*!

\page PhysicsTools_PythonAnalysis Package PhysicsTools/PythonAnalysis
<center>
<small>
<a href=http://cmssw.cvs.cern.ch/cgi-bin/cmssw.cgi/CMSSW/PhysicsTools/PythonAnalysis/?cvsroot=CMSSW>CVS head for this package</a> - 
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\section desc Description
<!-- Short description of what this package is supposed to provide -->
Examples of using CMSSW in Python. 
Some helper routines for startup, tab completion and shorter syntax.


\subsection interface Public interface
- <b>cmstools</b>: public interface to all modules.
 
\subsection modules Modules
- <b>cmstools.py</b>: prepares environment and defines some commands
- <b>cmscompleter.py</b>: class for tab completion
- <b>namespaceDict.py</b>: builds the FWLite namespace (without loading libs)
- <b>iterators.py></b>: decorator for adding iterators to some containers 

\subsection tests Unit tests and examples
- <b>interactive use</b>: all libraries are loaded automatically when needed. 
fire up the python interpreter
\htmlonly
<pre>
python
</pre>
\endhtmlonly
and import cmstools and ROOT:
\htmlonly
<pre>
from PhysicsTools.PythonAnalysis import *
from ROOT import *
</pre>
\endhtmlonly
That's it. 
- <b>MCTruth.py</b>: Reads gen event information and prints event number (root version)
- <b>MCTruth2.py</b>: Reads gen event information and prints event number (using cmstools)
- <b>trackerHits.py</b>: Reads sim event information and creates the files <tt>histo.root</tt> 
and <tt>tofhits.jpg</tt>.
\htmlonly
<ol>
<li>Prepare the environment and load the cms module:
<pre>
from PhysicsTools.PythonAnalysis.cmstools import *
from ROOT import *
</pre>
<li>Open ROOT file and access branch:
<pre>
events = EventTree.('simevents.root')
</pre>
<li>Prepare histogram and loop over all events to fill it
<pre>
histo = TH1F('tofhits', 'Tof of hits', 100, -0.5, 50)

for event in events:
    simHits = event.getProduct('PSimHit_r_TrackerHitsTIBLowTof.obj')
    for hit in simHits:
        histo.Fill(hit.timeOfFlight())
</pre>
<li>Save histogram in a file:
<pre>
hFile = TFile('histo.root', 'RECREATE')
histo.Write()
</pre>
<li>Plot histogram as a jpg-file:
<pre>
gROOT.SetBatch()
gROOT.SetStyle('Plain')

c = TCanvas()
histo.Draw()
c.SaveAs('tofhits.jpg')
</pre>
</ol>
\endhtmlonly

- <b>howto.txt</b>: short explanation

\section status Status and planned development
<!-- e.g. completed, stable, missing features -->
Prototype.

For more details, refer to the
<a href="https://twiki.cern.ch/twiki/bin/view/CMS/SWGuidePhysicsTools">Analysis Tools</a>
TWiki on the Software Guide.

<hr>
Last updated: 03-MAR-2007 B. Hegner
*/