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PixelVertexProducerMedian.cc
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2 
7 
10 
13 
14 #include <fstream>
15 #include <iostream>
16 #include <vector>
17 #include <algorithm>
18 
19 #include "TROOT.h"
20 #include "TH1F.h"
21 #include "TF1.h"
22 
23 /*****************************************************************************/
24 struct ComparePairs {
25  bool operator()(const reco::Track* t1, const reco::Track* t2) { return (t1->vz() < t2->vz()); };
26 };
27 
28 /*****************************************************************************/
30  thePtMin = theConfig.getParameter<double>("PtMin");
31  produces<reco::VertexCollection>();
32 }
33 
34 /*****************************************************************************/
36 
37 /*****************************************************************************/
39  // Get pixel tracks
41  std::string trackCollectionName = theConfig.getParameter<std::string>("TrackCollection");
42  ev.getByLabel(trackCollectionName, trackCollection);
43  const reco::TrackCollection tracks_ = *(trackCollection.product());
44 
45  // Select tracks
46  std::vector<const reco::Track*> tracks;
47  for (unsigned int i = 0; i < tracks_.size(); i++) {
48  if (tracks_[i].pt() > thePtMin) {
49  reco::TrackRef recTrack(trackCollection, i);
50  tracks.push_back(&(*recTrack));
51  }
52  }
53 
54  LogTrace("MinBiasTracking") << " [VertexProducer] selected tracks: " << tracks.size() << " (out of " << tracks_.size()
55  << ")";
56 
57  auto vertices = std::make_unique<reco::VertexCollection>();
58 
59  if (!tracks.empty()) {
60  // Sort along vertex z position
61  std::sort(tracks.begin(), tracks.end(), ComparePairs());
62 
63  // Median
64  float med;
65  if (tracks.size() % 2 == 0)
66  med = (tracks[tracks.size() / 2 - 1]->vz() + tracks[tracks.size() / 2]->vz()) / 2;
67  else
68  med = tracks[tracks.size() / 2]->vz();
69 
70  LogTrace("MinBiasTracking") << " [vertex position] median = " << med << " cm";
71 
72  if (tracks.size() > 10) {
73  // Binning around med, halfWidth
74  int nBin = 100;
75  float halfWidth = 0.1; // cm
76 
77  // Most probable
78  TH1F histo("histo", "histo", nBin, -halfWidth, halfWidth);
79 
80  for (std::vector<const reco::Track*>::const_iterator track = tracks.begin(); track != tracks.end(); track++)
81  if (fabs((*track)->vz() - med) < halfWidth)
82  histo.Fill((*track)->vz() - med);
83 
84  LogTrace("MinBiasTracking") << " [vertex position] most prob = "
85  << med + histo.GetBinCenter(histo.GetMaximumBin()) << " cm";
86 
87  // Fit above max/2
88  histo.Sumw2();
89 
90  TF1 f1("f1", "[0]*exp(-0.5 * ((x-[1])/[2])^2) + [3]");
91  f1.SetParameters(10., 0., 0.01, 1.);
92 
93  histo.Fit(&f1, "QN");
94 
95  LogTrace("MinBiasTracking") << " [vertex position] fitted = " << med + f1.GetParameter(1) << " +- "
96  << f1.GetParError(1) << " cm";
97 
98  // Store
100  err(2, 2) = f1.GetParError(1) * f1.GetParError(1);
101  reco::Vertex ver(reco::Vertex::Point(0, 0, med + f1.GetParameter(1)), err, 0, 1, 1);
102  vertices->push_back(ver);
103  } else {
104  // Store
106  err(2, 2) = 0.1 * 0.1;
107  reco::Vertex ver(reco::Vertex::Point(0, 0, med), err, 0, 1, 1);
108  vertices->push_back(ver);
109  }
110  }
111  ev.put(std::move(vertices));
112 }
T getParameter(std::string const &) const
Definition: ParameterSet.h:307
std::vector< Track > TrackCollection
collection of Tracks
Definition: TrackFwd.h:14
math::Error< dimension >::type Error
covariance error matrix (3x3)
Definition: Vertex.h:44
#define LogTrace(id)
PixelVertexProducerMedian(const edm::ParameterSet &ps)
math::XYZPoint Point
point in the space
Definition: Vertex.h:40
trackCollection
Definition: JetHT_cfg.py:51
bool operator()(const reco::Track *t1, const reco::Track *t2)
void produce(edm::StreamID, edm::Event &ev, const edm::EventSetup &es) const override
def move(src, dest)
Definition: eostools.py:511