ntupleDataFormat.py

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from builtins import range
import math
import collections

import ROOT

from Validation.RecoTrack.plotting.ntupleEnum import *
from Validation.RecoTrack.plotting.ntupleEnum import _Enum

class _Collection(object):
    """Adaptor class representing a collection of objects.

    Concrete collection classes should inherit from this class.

    """
    def __init__(self, tree, sizeBranch, objclass):
        """Constructor.

        Arguments:
        tree        -- TTree object
        sizeBranch  -- Name of the branch to be used in size()
        objclass    -- Class to be used for the objects in __getitem__()
        """
        super(_Collection, self).__init__()
        self._tree = tree
        self._sizeBranch = sizeBranch
        self._objclass = objclass

    def size(self):
        """Number of objects in the collection."""
        return int(getattr(self._tree, self._sizeBranch).size())

    def __len__(self):
        """Number of objects in the collection."""
        return self.size()

    def __getitem__(self, index):
        """Get object 'index' in the collection."""
        return self._objclass(self._tree, index)

    def __iter__(self):
        """Returns generator for the objects."""
        for index in range(self.size()):
            yield self._objclass(self._tree, index)

class _Object(object):
    """Adaptor class representing a single object in a collection.

    The member variables of the object are obtained from the branches
    with common prefix and a given index.

    Concrete object classes should inherit from this class.
    """
    def __init__(self, tree, index, prefix):
        """Constructor.

        Arguments:
        tree   -- TTree object
        index  -- Index for this object
        prefix -- Prefix of the branchs
        """
        super(_Object, self).__init__()
        self._tree = tree
        self._index = index
        self._prefix = prefix

    def __getattr__(self, attr):
        """Return object member variable.

        'attr' is translated as a branch in the TTree (<prefix>_<attr>).
        """
        self._checkIsValid()
        val = getattr(self._tree, self._prefix+"_"+attr)[self._index]
        return lambda: val

    def _checkIsValid(self):
        """Raise an exception if the object index is not valid."""
        if not self.isValid():
            raise Exception("%s is not valid" % self.__class__.__name__)

    def isValid(self):
        """Check if object index is valid."""
        return self._index != -1

    def index(self):
        """Return object index."""
        return self._index

class _DetIdStrAdaptor(object):
    """Adaptor class for objects containgin DetId (hits)."""
    def __init__(self):
        super(_DetIdStrAdaptor, self).__init__()

    def layerStr(self):
        """Returns a string describing the layer of the hit."""
        self._checkIsValid()
        get = lambda name: getattr(self._tree, self._prefix+"_"+name)[self._index]
        subdet = get("subdet")
        side = ""
        isPhase2OTBarrel = (subdet == SubDet.TOB and hasattr(self._tree, self._prefix+"_isLower"))
        if subdet in [SubDet.FPix, SubDet.TID, SubDet.TEC] or isPhase2OTBarrel:
            sideNum = get("side")
            if sideNum == 1:
                side = "-"
            elif sideNum == 2:
                side = "+"
            elif isPhase2OTBarrel and sideNum == 3:
                side = ""
            else:
                side = "?"
        return "%s%d%s" % (SubDet.toString(subdet),
                           getattr(self._tree, self._prefix+"_layer")[self._index],
                           side)

    def detIdStr(self):
        """Returns a string describing the DetId fields."""
        self._checkIsValid
        get = lambda name: getattr(self._tree, self._prefix+"_"+name)[self._index]
        isPhase2 = hasattr(self._tree, self._prefix+"_isLower")
        def stereo():
            if isPhase2:
                if get("isLower"):
                    return " isLower"
                if get("isUpper"):
                    return " isUpper"
                if get("isStack"):
                    return " isStack"
            else:
                if get("isStereo"):
                    return " isStereo"
                if get("isRPhi"):
                    return " isRPhi"
                if get("isGlued"):
                    return " isGlued"
            return ""

        subdet = get("subdet")
        if subdet == SubDet.BPix:
            return "ladder {} module {}".format(get("ladder"), get("module"))
        if subdet == SubDet.FPix:
            return "blade {} panel {} module {}".format(get("blade"), get("panel"), get("module"))
        if subdet == SubDet.TIB:
            return "side {} order {} string {} module {}{}".format(get("side"), get("order"), get("string"), get("module"), stereo())
        if subdet == SubDet.TID:
            return "ring {} order {} module {}{}".format(get("ring"), get("order"), get("module"), stereo())
        if subdet == SubDet.TOB:
            if isPhase2:
                return "rod {} module {}{}".format(get("rod"), get("module"), stereo())
            else:
                return "side {} rod {} module {}{}".format(get("side"), get("rod"), get("module"), stereo())
        if subdet == SubDet.TEC:
            return "order {} petal {} ring {} module {}{}".format(get("order"), get("petalNumber"), get("ring"), get("module"), stereo())
        raise Exception("Unknown subdet %d" % subdet)

class _HitObject(_Object, _DetIdStrAdaptor):
    """Adaptor class for pixel/strip hit objects."""
    def __init__(self, tree, index, prefix):
        """Constructor.

        Arguments:
        tree   -- TTree object
        index  -- Index for this object
        prefix -- Prefix of the branchs
        """
        """Constructor
        """
        super(_HitObject, self).__init__(tree, index, prefix)

    def ntracks(self):
        """Returns number of tracks containing this hit."""
        self._checkIsValid()
        return getattr(self._tree, self._prefix+"_trkIdx")[self._index].size()

    def tracks(self):
        """Returns generator for tracks containing this hit.

        The generator returns Track objects
        """
        self._checkIsValid()
        for itrack in getattr(self._tree, self._prefix+"_trkIdx")[self._index]:
            yield Track(self._tree, itrack)

    def nseeds(self):
        """Returns number of seeds containing this hit."""
        self._checkIsValid()
        return getattr(self._tree, self._prefix+"_seeIdx")[self._index].size()

    def seeds(self):
        """Returns generator for tracks containing this hit.

        The generator returns Seed objects
        """
        self._checkIsValid()
        for iseed in getattr(self._tree, self._prefix+"_seeIdx")[self._index]:
            yield Seed(self._tree, iseed)

    def r(self):
        return math.sqrt(self.x()**2 + self.y()**2)

    def r3D(self):
        return math.sqrt(self.x()**2 + self.y()**2 + self.z()**2)

class _RecoHitAdaptor(object):
    """Adaptor class for objects containing hits (e.g. tracks)"""
    def __init__(self):
        super(_RecoHitAdaptor, self).__init__()

    def _hits(self):
        """Internal method to generate pairs of hit index and type."""
        for ihit, hitType in zip(self.hitIdx(), self.hitType()):
            yield (ihit, hitType)

    def hits(self):
        """Returns generator for hits.

        Generator returns PixelHit/StripHit/GluedHit/Phase2OT depending on the
        hit type.

        """
        for ihit, hitType in self._hits():
            if hitType == 0:
                yield PixelHit(self._tree, ihit)
            elif hitType == 1:
                yield StripHit(self._tree, ihit)
            elif hitType == 2:
                yield GluedHit(self._tree, ihit)
            elif hitType == 3:
                yield InvalidHit(self._tree, ihit)
            elif hitType == 4:
                yield Phase2OTHit(self._tree, ihit)
            else:
                raise Exception("Unknown hit type %d" % hitType)

    def pixelHits(self):
        """Returns generator for pixel hits."""
        self._checkIsValid()
        for ihit, hitType in self._hits():
            if hitType != 0:
                continue
            yield PixelHit(self._tree, ihit)

    def stripHits(self):
        """Returns generator for strip hits."""
        self._checkIsValid()
        for ihit, hitType in self._hits():
            if hitType != 1:
                continue
            yield StripHit(self._tree, ihit)

    def gluedHits(self):
        """Returns generator for matched strip hits."""
        self._checkIsValid()
        for ihit, hitType in self._hits():
            if hitType != 2:
                continue
            yield GluedHit(self._tree, ihit)

    def invalidHits(self):
        """Returns generator for invalid hits."""
        self._checkIsValid()
        for ihit, hitType in self._hits():
            if hitType != 3:
                continue
            yield InvalidHit(self._tree, ihit)

    def phase2OTHits(self):
        """Returns generator for phase2 outer tracker hits."""
        self._checkIsValid()
        for ihit, hitType in self._hits():
            if hitType != 4:
                continue
            yield Phase2OTHit(self._tree, ihit)

class _SimHitMatchAdaptor(object):
    """Adaptor class for objects containing or matched to SimHits (e.g. reco hits)."""
    def __init__(self):
        super(_SimHitMatchAdaptor, self).__init__()

    def _nMatchedSimHits(self):
        """Internal method to get the number of matched SimHits."""
        return getattr(self._tree, self._prefix+"_simHitIdx")[self._index].size()

    def nMatchedSimHits(self):
        """Returns the number of matched SimHits."""
        self._checkIsValid()
        return self._nMatchedSimHits()

    def matchedSimHitInfos(self):
        """Returns a generator for matched SimHits.

        The generator returns SimHitMatchInfo objects.
        """
        self._checkIsValid()
        for imatch in range(self._nMatchedSimHits()):
            yield SimHitMatchInfo(self._tree, self._index, imatch, self._prefix)

class _TrackingParticleMatchAdaptor(object):
    """Adaptor class for objects matched to TrackingParticles."""
    def __init__(self):
        super(_TrackingParticleMatchAdaptor, self).__init__()

    def _nMatchedTrackingParticles(self):
        """Internal method to get the number of matched TrackingParticles."""
        return getattr(self._tree, self._prefix+"_simTrkIdx")[self._index].size()

    def nMatchedTrackingParticles(self):
        """Returns the number of matched TrackingParticles."""
        self._checkIsValid()
        return self._nMatchedTrackingParticles()

    def matchedTrackingParticleInfos(self):
        """Returns a generator for matched TrackingParticles.

        The generator returns TrackingParticleMatchInfo objects.

        """
        self._checkIsValid()
        for imatch in range(self._nMatchedTrackingParticles()):
            yield TrackingParticleMatchInfo(self._tree, self._index, imatch, self._prefix)

    def bestMatchingTrackingParticle(self):
        """Returns best-matching TrackingParticle, even for fake tracks, or None if there is no best-matching TrackingParticle.

        Best-matching is defined as the one with largest number of
        hits matched to the hits of a track (>= 3). If there are many
        fulfilling the same number of hits, the one inducing the
        innermost hit of the track is chosen.
        """
        idx = self.bestSimTrkIdx()
        if idx < 0:
            return None
        return TrackingParticle(self._tree, idx)

    def bestMatchingTrackingParticleShareFrac(self):
        """Fraction of shared hits with reco hits as denominator for best-matching TrackingParticle."""
        return self.bestSimTrkShareFrac()

    def bestMatchingTrackingParticleShareFracSimDenom(self):
        """Fraction of shared hits with TrackingParticle::numberOfTrackerHits() as denominator for best-matching TrackingParticle."""
        return self.bestSimTrkShareFracSimDenom()

    def bestMatchingTrackingParticleShareFracSimClusterDenom(self):
        """Fraction of shared hits with number of reco clusters associated to a TrackingParticle as denominator for best-matching TrackingParticle."""
        return self.bestSimTrkShareFracSimClusterDenom()

    def bestMatchingTrackingParticleNormalizedChi2(self):
        """Normalized chi2 calculated from track parameters+covariance matrix and TrackingParticle parameters for best-matching TrackingParticle."""
        return self.bestSimTrkNChi2()

    def bestMatchingTrackingParticleFromFirstHit(self):
        """Returns best-matching TrackingParticle, even for fake tracks, or None if there is no best-matching TrackingParticle.

        Best-matching is defined as the one with largest number of
        hits matched to the hits of a track (>= 3) starting from the
        beginning of the track. If there are many fulfilling the same
        number of hits, "a first TP" is chosen (a bit arbitrary, but
        should be rare".
        """
        idx = self.bestFromFirstHitSimTrkIdx()
        if idx < 0:
            return None
        return TrackingParticle(self._tree, idx)

    def bestMatchingTrackingParticleFromFirstHitShareFrac(self):
        """Fraction of shared hits with reco hits as denominator for best-matching TrackingParticle starting from the first hit of a track."""
        return self.bestFromFirstHitSimTrkShareFrac()

    def bestMatchingTrackingParticleFromFirstHitShareFracSimDenom(self):
        """Fraction of shared hits with TrackingParticle::numberOfTrackerHits() as denominator for best-matching TrackingParticle starting from the first hit of a track."""
        return self.bestFromFirstHitSimTrkShareFracSimDenom()

    def bestMatchingTrackingParticleFromFirstHitShareFracSimClusterDenom(self):
        """Fraction of shared hits with number of reco clusters associated to a TrackingParticle as denominator for best-matching TrackingParticle starting from the first hit of a track."""
        return self.bestFromFirstHitSimTrkShareFracSimClusterDenom()

    def bestMatchingTrackingParticleFromFirstHitNormalizedChi2(self):
        """Normalized chi2 calculated from track parameters+covariance matrix and TrackingParticle parameters for best-matching TrackingParticle starting from the first hit of a track."""
        return self.bestFromFirstHitSimTrkNChi2()


class TrackingNtuple(object):
    """Class abstracting the whole ntuple/TTree.

    Main benefit is to provide nice interface for
    - iterating over events
    - querying whether hit/seed information exists

    Note that to iteratate over the evets with zip(), you should use
    itertools.izip() instead.
    """
    def __init__(self, fileName, tree="trackingNtuple/tree"):
        """Constructor.

        Arguments:
        fileName -- String for path to the ROOT file
        tree     -- Name of the TTree object inside the ROOT file (default: 'trackingNtuple/tree')
        """
        super(TrackingNtuple, self).__init__()
        self._file = ROOT.TFile.Open(fileName)
        self._tree = self._file.Get(tree)
        self._entries = self._tree.GetEntriesFast()

    def file(self):
        return self._file

    def tree(self):
        return self._tree

    def nevents(self):
        return self._entries

    def hasHits(self):
        """Returns true if the ntuple has hit information."""
        return hasattr(self._tree, "pix_isBarrel")

    def hasSeeds(self):
        """Returns true if the ntuple has seed information."""
        return hasattr(self._tree, "see_fitok")

    def __iter__(self):
        """Returns generator for iterating over TTree entries (events)

        Generator returns Event objects.

        """
        for jentry in range(self._entries):
            # get the next tree in the chain and verify
            ientry = self._tree.LoadTree( jentry )
            if ientry < 0: break
            # copy next entry into memory and verify
            nb = self._tree.GetEntry( jentry )
            if nb <= 0: continue

            yield Event(self._tree, jentry)

    def getEvent(self, index):
        """Returns Event for a given index"""
        ientry = self._tree.LoadTree(index)
        if ientry < 0: return None
        nb = self._tree.GetEntry(ientry) # ientry or jentry?
        if nb <= 0: None

        return Event(self._tree, ientry) # ientry of jentry?


class Event(object):
    """Class abstracting a single event.

    Main benefit is to provide nice interface to get various objects
    or collections of objects.
    """
    def __init__(self, tree, entry):
        """Constructor.

        Arguments:
        tree  -- TTree object
        entry -- Entry number in the tree
        """
        super(Event, self).__init__()
        self._tree = tree
        self._entry = entry

    def entry(self):
        return self._entry

    def event(self):
        """Returns event number."""
        return self._tree.event

    def lumi(self):
        """Returns lumisection number."""
        return self._tree.lumi

    def run(self):
        """Returns run number."""
        return self._tree.run

    def eventId(self):
        """Returns (run, lumi, event) tuple."""
        return (self._tree.run, self._tree.lumi, self._tree.event)

    def eventIdStr(self):
        """Returns 'run:lumi:event' string."""
        return "%d:%d:%d" % self.eventId()

    def beamspot(self):
        """Returns BeamSpot object."""
        return BeamSpot(self._tree)

    def tracks(self):
        """Returns Tracks object."""
        return Tracks(self._tree)

    def pixelHits(self):
        """Returns PixelHits object."""
        return PixelHits(self._tree)

    def stripHits(self):
        """Returns StripHits object."""
        return StripHits(self._tree)

    def gluedHits(self):
        """Returns GluedHits object."""
        return GluedHits(self._tree)

    def phase2OTHits(self):
        """Returns Phase2OTHits object."""
        return Phase2OTHits(self._tree)

    def seeds(self):
        """Returns Seeds object."""
        return Seeds(self._tree)

    def trackingParticles(self):
        """Returns TrackingParticles object."""
        return TrackingParticles(self._tree)

    def vertices(self):
        """Returns Vertices object."""
        return Vertices(self._tree)

    def trackingVertices(self):
        """Returns TrackingVertices object."""
        return TrackingVertices(self._tree)


class BeamSpot(object):
    """Class representing the beam spot."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(BeamSpot, self).__init__()
        self._tree = tree
        self._prefix = "bsp"

    def __getattr__(self, attr):
        """Return object member variable.

        'attr' is translated as a branch in the TTree (bsp_<attr>).
        """
        val = getattr(self._tree, self._prefix+"_"+attr)
        return lambda: val


class SimHitMatchInfo(_Object):
    """Class representing a match to a SimHit.

    The point of this class is to provide, in addition to the matched
    SimHit, also other information about the match (e.g. fraction of
    charge from this SimHit).
    """
    def __init__(self, tree, index, shindex, prefix):
        """Constructor.

        Arguments:
        tree    -- TTree object
        index   -- Index of the hit matched to SimHit
        shindex -- Index of the SimHit match (second index in _simHitIdx branch)
        prefix  -- String for prefix of the object (track/seed/hit) matched to TrackingParticle
        """
        super(SimHitMatchInfo, self).__init__(tree, index, prefix)
        self._shindex = shindex

    def __getattr__(self, attr):
        """Custom __getattr__ because of the second index needed to access the branch."""
        val = super(SimHitMatchInfo, self).__getattr__(attr)()[self._shindex]
        return lambda: val

    def simHit(self):
        """Returns matched SimHit."""
        self._checkIsValid()
        return SimHit(self._tree, getattr(self._tree, self._prefix+"_simHitIdx")[self._index][self._shindex])

class TrackingParticleMatchInfo(_Object):

    """Class representing a match to a TrackingParticle.

    The point of this class is to provide, in addition to the matched
    TrackingParticle, also other information about the match (e.g.
    shared hit fraction for tracks/seeds).
    """
    def __init__(self, tree, index, tpindex, prefix):
        """Constructor.

        Arguments:
        tree    -- TTree object
        index   -- Index of the object (track/seed) matched to TrackingParticle
        tpindex -- Index of the TrackingParticle match (second index in _simTrkIdx branch)
        prefix  -- String for prefix of the object (track/seed) matched to TrackingParticle
        """
        super(TrackingParticleMatchInfo, self).__init__(tree, index, prefix)
        self._tpindex = tpindex

    def __getattr__(self, attr):
        """Custom __getattr__ because of the second index needed to access the branch.

        Note that when mapping the 'attr' to a branch, a 'simTrk' is
        prepended and the first letter of 'attr' is turned to upper
        case.
        """
        val = super(TrackingParticleMatchInfo, self).__getattr__("simTrk"+attr[0].upper()+attr[1:])()[self._tpindex]
        return lambda: val

    def trackingParticle(self):
        """Returns matched TrackingParticle."""
        return TrackingParticle(self._tree, self.idx())

class TrackMatchInfo(_Object):
    """Class representing a match to a Track.

    The point of this class is to provide, in addition to the matched
    Track, also other information about the match (e.g. shared hit fraction.
    """
    def __init__(self, tree, index, trkindex, prefix):
        """Constructor.

        Arguments:
        tree     -- TTree object
        index    -- Index of the object (TrackingParticle) matched to track
        trkindex -- Index of the track match (second index in _trkIdx branch)
        prefix   -- String for prefix of the object (TrackingParticle) matched to track
        """
        super(TrackMatchInfo, self).__init__(tree, index, prefix)
        self._trkindex = trkindex

    def __getattr__(self, attr):
        """Custom __getattr__ because of the second index needed to access the branch.

        Note that when mapping the 'attr' to a branch, a 'trk' is
        prepended and the first letter of 'attr' is turned to upper
        case.
        """
        val = super(TrackMatchInfo, self).__getattr__("trk"+attr[0].upper()+attr[1:])()[self._trkindex]
        return lambda: val

    def track(self):
        """Returns matched Track."""
        return Track(self._tree, self.idx())

class SeedMatchInfo(_Object):
    """Class representing a match to a Seed.

    The point of this class is to provide an interface compatible with
    all other "MatchInfo" classes

    """
    def __init__(self, tree, index, seedindex, prefix):
        """Constructor.

        Arguments:
        tree     -- TTree object
        index    -- Index of the object (TrackingParticle) matched to seed
        seedindex -- Index of the seed match (second index in _trkIdx branch)
        prefix   -- String for prefix of the object (TrackingParticle) matched to seed
        """
        super(SeedMatchInfo, self).__init__(tree, index, prefix)
        self._seedindex = seedindex

    def seed(self):
        """Returns matched Seed."""
        self._checkIsValid()
        return Seed(self._tree, getattr(self._tree, self._prefix+"_seedIdx")[self._index][self._seedindex])


class Track(_Object, _RecoHitAdaptor, _TrackingParticleMatchAdaptor):
    """Class presenting a track."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the track
        """
        super(Track, self).__init__(tree, index, "trk")

    def seed(self):
        """Returns Seed of the track."""
        self._checkIsValid()
        return Seed(self._tree, self._tree.trk_seedIdx[self._index])

    def vertex(self):
        """Returns Vertex that used this track in its fit."""
        self._checkIsValid()
        return Vertex(self._tree, self._tree.trk_vtxIdx[self._index])

    def ptPull(self):
        tp = self.bestMatchingTrackingParticle()
        if tp is None:
            return None
        return (self.pt() - tp.pca_pt())/self.ptErr()

    def thetaPull(self):
        tp = self.bestMatchingTrackingParticle()
        if tp is None:
            return None
        return (getattr(self, "lambda")() - tp.pca_lambda())/self.lambdaErr() # as in MTV

    def phiPull(self):
        tp = self.bestMatchingTrackingParticle()
        if tp is None:
            return None
        return (self.phi() - tp.pca_phi())/self.phiErr()

    def dxyPull(self):
        tp = self.bestMatchingTrackingParticle()
        if tp is None:
            return None
        return (self.dxy() - tp.pca_dxy())/self.dxyErr()

    def dzPull(self):
        tp = self.bestMatchingTrackingParticle()
        if tp is None:
            return None
        return (self.dz() - tp.pca_dz())/self.dzErr()

class Tracks(_Collection):
    """Class presenting a collection of tracks."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(Tracks, self).__init__(tree, "trk_pt", Track)


class PixelHit(_HitObject, _SimHitMatchAdaptor):
    """Class representing a pixel hit."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the hit
        """
        super(PixelHit, self).__init__(tree, index, "pix")

    def isValidHit(self):
        return True

class PixelHits(_Collection):
    """Class presenting a collection of pixel hits."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(PixelHits, self).__init__(tree, "pix_isBarrel", PixelHit)


class StripHit(_HitObject, _SimHitMatchAdaptor):
    """Class representing a strip hit."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the hit
        """
        super(StripHit, self).__init__(tree, index, "str")

    def isValidHit(self):
        return True

class StripHits(_Collection):
    """Class presenting a collection of strip hits."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(StripHits, self).__init__(tree, "str_isBarrel", StripHit)


class GluedHit(_Object, _DetIdStrAdaptor):
    """Class representing a matched strip hit."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the hit
        """
        super(GluedHit, self).__init__(tree, index, "glu")

    def isValidHit(self):
        return True

    def monoHit(self):
        """Returns a StripHit for the mono hit."""
        self._checkIsValid()
        return StripHit(self._tree, self._tree.glu_monoIdx[self._index])

    def stereoHit(self):
        """Returns a StripHit for the stereo hit."""
        self._checkIsValid()
        return StripHit(self._tree, self._tree.glu_stereoIdx[self._index])

    def nseeds(self):
        """Returns the number of seeds containing this hit."""
        self._checkIsValid()
        return self._tree.glu_seeIdx[self._index].size()

    def seeds(self):
        """Returns generator for seeds containing this hit.

        The generator returns Seed objects
        """
        self._checkIsValid()
        for iseed in self._tree.glu_seeIdx[self._index]:
            yield Seed(self._tree, iseed)

class GluedHits(_Collection):
    """Class presenting a collection of matched strip hits."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(GluedHits, self).__init__(tree, "glu_isBarrel", GluedHit)


class InvalidHit(_Object, _DetIdStrAdaptor):
    # repeating TrackingRecHit::Type
    Type = _Enum(
        missing = 1,
        inactive = 2,
        bad = 3,
        missing_inner = 4,
        missing_outer = 5
    )

    """Class representing an invalid hit."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the hit
        """
        super(InvalidHit, self).__init__(tree, index, "inv")

    def isValidHit(self):
        return False

    def layerStr(self):
        """Returns a string describing the layer of the hit."""
        invalid_type = self._tree.inv_type[self._index]
        return super(InvalidHit, self).layerStr() + " (%s)"%InvalidHit.Type.toString(invalid_type)


class Phase2OTHit(_HitObject, _SimHitMatchAdaptor):
    """Class representing a phase2 OT hit."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the hit
        """
        super(Phase2OTHit, self).__init__(tree, index, "ph2")

    def isValidHit(self):
        return True

class Phase2OTHits(_Collection):
    """Class presenting a collection of phase2 OT hits."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(Phase2OTHits, self).__init__(tree, "ph2_isBarrel", Phase2OTHit)


def _seedOffsetForAlgo(tree, algo):
    """Internal function for returning a pair of indices for the beginning of seeds of a given 'algo', and the one-beyond-last index of the seeds."""
    for ioffset, offset in enumerate(tree.see_offset):
        if tree.see_algo[offset] == algo:
            next_offset = tree.see_offset[ioffset+1] if ioffset < tree.see_offset.size()-1 else tree.see_algo.size()
            return (offset, next_offset)
    return (-1, -1)

class Seed(_Object, _RecoHitAdaptor, _TrackingParticleMatchAdaptor):
    """Class presenting a seed."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the seed
        """
        super(Seed, self).__init__(tree, index, "see")

    def indexWithinAlgo(self):
        """Returns the seed index within the seeds of the same algo.

        In case of errors, -1 is returned.
        """
        self._checkIsValid()
        algo = self._tree.see_algo[self._index]
        (offset, next_offset) = _seedOffsetForAlgo(self._tree, algo)
        if offset == -1: # algo not found
            return -1
        return self._index - offset

    def track(self):
        """Returns Track that was made from this seed."""
        self._checkIsValid()
        return Track(self._tree, self._tree.see_trkIdx[self._index])

class Seeds(_Collection):
    """Class presenting a collection of seeds."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(Seeds, self).__init__(tree, "see_pt", Seed)

    def nSeedsForAlgo(self, algo):
        """Returns the number of seeds for a given 'algo'."""
        (offset, next_offset) = _seedOffsetForAlgo(self._tree, algo)
        return next_offset - offset

    def seedsForAlgo(self, algo):
        """Returns generator iterating over the seeds of a given 'algo'.

        Generator returns Seed object.
        """
        (offset, next_offset) = _seedOffsetForAlgo(self._tree, algo)
        for isee in range(offset, next_offset):
            yield Seed(self._tree, isee)

    def seedForAlgo(self, algo, iseed):
        """Returns Seed of index 'iseed' for 'algo'."""
        (offset, next_offset) = _seedOffsetForAlgo(self._tree, algo)
        if iseed >= (next_offset-offset):
            raise Exception("Seed index %d is larger than the number of seeds %d for algo %d (%s)" % (iseed, next_offset-offset, algo, Algo.toString(algo)))
        return Seed(self._tree, offset+iseed)


class SimHit(_Object, _DetIdStrAdaptor, _RecoHitAdaptor):
    """Class representing a SimHit which has not induced a RecHit."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the SimHit
        """
        super(SimHit, self).__init__(tree, index, "simhit")

    def nRecHits(self):
        self._checkIsValid()
        return self._tree.simhit_hitIdx[self._index].size()

    def trackingParticle(self):
        self._checkIsValid()
        return TrackingParticle(self._tree, getattr(self._tree, self._prefix+"_simTrkIdx")[self._index])


class TrackingParticle(_Object):
    """Class representing a TrackingParticle."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the TrackingParticle
        """
        super(TrackingParticle, self).__init__(tree, index, "sim")

    def _nMatchedTracks(self):
        """Internal function to get the number of matched tracks."""
        return self._tree.sim_trkIdx[self._index].size()

    def nMatchedTracks(self):
        """Returns the number of matched tracks."""
        self._checkIsValid()
        return self._nMatchedTracks()

    def matchedTrackInfos(self):
        """Returns a generator for matched tracks.

        The generator returns TrackMatchInfo objects.
        """
        self._checkIsValid()
        for imatch in range(self._nMatchedTracks()):
            yield TrackMatchInfo(self._tree, self._index, imatch, self._prefix)

    def bestMatchingTrack(self):
        """Returns best-matching track, even for non-reconstructed TrackingParticles, or None, if there is no best-matching track.

        Best-matching is defined as the one with largest number of
        hits matched to the hits of a TrackingParticle (>= 3). If
        there are many fulfilling the same number of hits, the one
        inducing the innermost hit of the TrackingParticle is chosen.
        """
        self._checkIsValid()
        if self._nMatchedTracks() == 1:
            return next(self.matchedTrackInfos()).track()

        tracks = collections.OrderedDict()
        for hit in self.simHits():
            for recHit in hit.hits():
                for track in recHit.tracks():
                    if track.index() in tracks:
                        tracks[track.index()] += 1
                    else:
                        tracks[track.index()] = 1

        best = (None, 2)
        for trackIndex, nhits in tracks.items():
            if nhits > best[1]:
                best = (trackIndex, nhits)
        if best[0] is None:
            return None
        return Tracks(self._tree)[best[0]]

    def _nMatchedSeeds(self):
        """Internal function to get the number of matched seeds."""
        return self._tree.sim_seedIdx[self._index].size()

    def nMatchedSeeds(self):
        """Returns the number of matched seeds."""
        self._checkIsValid()
        return self._nMatchedSeeds()

    def matchedSeedInfos(self):
        """Returns a generator for matched tracks.

        The generator returns SeedMatchInfo objects.
        """
        self._checkIsValid()
        for imatch in range(self._nMatchedSeeds()):
            yield SeedMatchInfo(self._tree, self._index, imatch, self._prefix)

    def nSimHits(self):
        self._checkIsValid()
        return self.simHitIdx().size()

    def simHits(self):
        """Returns generator for SimHits."""
        self._checkIsValid()
        for ihit in self.simHitIdx():
            yield SimHit(self._tree, ihit)

    def parentVertex(self):
        """Returns the parent TrackingVertex."""
        self._checkIsValid()
        return TrackingVertex(self._tree, self._tree.sim_parentVtxIdx[self._index])

    def decayVertices(self):
        """Returns a generator for decay vertices.

        The generator returns TrackingVertex objects.
        """
        self._checkIsValid()
        for ivtx in self._tree.sim_decayVtxIdx[self._index]:
            yield TrackingVertex(self._tree, ivtx)

    def isLooper(self):
        """Returns True if this TrackingParticle is a looper.

        Note that the check involves looping over the SimHits, so it is not too cheap."""
        self._checkIsValid()
        prevr = 0
        for ihit in self.simHitIdx():
            hit = SimHit(self._tree, ihit)
            r = hit.x()**2 + hit.y()**2
            if r < prevr:
                return True
            prevr = r
        return False


class TrackingParticles(_Collection):
    """Class presenting a collection of TrackingParticles."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(TrackingParticles, self).__init__(tree, "sim_pt", TrackingParticle)


class Vertex(_Object):
    """Class presenting a primary vertex."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the vertex
        """
        super(Vertex, self).__init__(tree, index, "vtx")

    def nTracks(self):
        """Returns the number of tracks used in the vertex fit."""
        self._checkIsValid()
        return self._tree.vtx_trkIdx[self._index].size()

    def tracks(self):
        """Returns a generator for the tracks used in the vertex fit.

        The generator returns Track object.
        """
        self._checkIsValid()
        for itrk in self._tree.vtx_trkIdx[self._index]:
            yield Track(self._tree, itrk)

class Vertices(_Collection):
    """Class presenting a collection of vertices."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(Vertices, self).__init__(tree, "vtx_valid", Vertex)


class TrackingVertex(_Object):
    """Class representing a TrackingVertex."""
    def __init__(self, tree, index):
        """Constructor.

        Arguments:
        tree  -- TTree object
        index -- Index of the TrackingVertex
        """
        super(TrackingVertex, self).__init__(tree, index, "simvtx")

    def nSourceTrackingParticles(self):
        """Returns the number of source TrackingParticles."""
        self._checkIsValid()
        return self._tree.simvtx_sourceSimIdx[self._index].size()

    def nDaughterTrackingParticles(self):
        """Returns the number of daughter TrackingParticles."""
        self._checkIsValid()
        return self._tree.simvtx_daughterSimIdx[self._index].size()

    def sourceTrackingParticles(self):
        """Returns a generator for the source TrackingParticles."""
        self._checkIsValid()
        for isim in self._tree.simvtx_sourceSimIdx[self._index]:
            yield TrackingParticle(self._tree, isim)

    def daughterTrackingParticles(self):
        """Returns a generator for the daughter TrackingParticles."""
        self._checkIsValid()
        for isim in self._tree.simvtx_daughterSimIdx[self._index]:
            yield TrackingParticle(self._tree, isim)

class TrackingVertices(_Collection, TrackingVertex):
    """Class presenting a collection of TrackingVertices."""
    def __init__(self, tree):
        """Constructor.

        Arguments:
        tree -- TTree object
        """
        super(TrackingVertex, self).__init__(tree, "simvtx_x")