Multidimensional histogram.
Use a THn if you really, really have to store more than three dimensions, and if a large fraction of all bins are filled. Better alternatives are
The major problem of THn is the memory use caused by n-dimensional histogramming: a THnD with 8 dimensions and 100 bins per dimension needs more than 2.5GB of RAM!
To construct a THn object you must use one of its templated, derived classes:
THnD (typedef for THnT<Double_t>): bin content held by a Double_t,
THnF (typedef for THnT<Float_t>): bin content held by a Float_t,
THnL (typedef for THnT<Long_t>): bin content held by a Long_t,
THnI (typedef for THnT<Int_t>): bin content held by an Int_t,
THnS (typedef for THnT<Short_t>): bin content held by a Short_t,
THnC (typedef for THnT<Char_t>): bin content held by a Char_t,
They take name and title, the number of dimensions, and for each dimension the number of bins, the minimal, and the maximal value on the dimension's axis. A TH2F h("h","h",10, 0., 10., 20, -5., 5.) would correspond to
Int_t bins[2] = {10, 20};
Double_t xmin[2] = {0., -5.};
Double_t xmax[2] = {10., 5.};
THnF hn("hn", "hn", 2, bins, xmin, xmax);
Filling
A THn is filled just like a regular histogram, using THn::Fill(x, weight), where x is a n-dimensional Double_t value. To take errors into account, Sumw2() must be called before filling the histogram. Storage is allocated when the first bin content is stored.
Projections
The dimensionality of a THn can be reduced by projecting it to 1, 2, 3, or n dimensions, which can be represented by a TH1, TH2, TH3, or a THn. See the Projection() members. To only project parts of the histogram, call
hn->GetAxis(12)->SetRange(from_bin, to_bin);
Conversion from other histogram classes
The static factory function THn::CreateHn() can be used to create a THn from a TH1, TH2, TH3, THnSparse and (for copying) even from a THn. The created THn will have compatble storage type, i.e. calling CreateHn() on a TH2F will create a THnF.
Definition at line 36 of file THn.h.
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virtual | ~THn () |
| Destruct a THn. More...
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void | AddBinContent (const Int_t *idx, Double_t v=1.) |
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void | AddBinContent (Long64_t bin, Double_t v=1.) |
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void | AddBinError2 (Long64_t bin, Double_t e2) |
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ROOT::Internal::THnBaseBinIter * | CreateIter (Bool_t respectAxisRange) const |
| Create an iterator over all bins. Public interface is THnIter. More...
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void | FillBin (Long64_t bin, Double_t w) |
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virtual const TNDArray & | GetArray () const =0 |
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virtual TNDArray & | GetArray ()=0 |
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Long64_t | GetBin (const Int_t *idx) const |
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Long64_t | GetBin (const Double_t *x) const |
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Long64_t | GetBin (const char *name[]) const |
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Long64_t | GetBin (const Int_t *idx, Bool_t=kTRUE) |
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Long64_t | GetBin (const Double_t *x, Bool_t=kTRUE) |
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Long64_t | GetBin (const char *name[], Bool_t=kTRUE) |
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Double_t | GetBinContent (const Int_t *idx) const |
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Double_t | GetBinContent (Long64_t bin, Int_t *idx=0) const |
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Double_t | GetBinError2 (Long64_t linidx) const |
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Long64_t | GetNbins () const |
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TH1D * | Projection (Int_t xDim, Option_t *option="") const |
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TH2D * | Projection (Int_t yDim, Int_t xDim, Option_t *option="") const |
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TH3D * | Projection (Int_t xDim, Int_t yDim, Int_t zDim, Option_t *option="") const |
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THn * | Projection (Int_t ndim, const Int_t *dim, Option_t *option="") const |
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THn * | Rebin (Int_t group) const |
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THn * | Rebin (const Int_t *group) const |
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void | Reset (Option_t *option="") |
| Reset the contents of a THn. More...
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void | SetBinContent (const Int_t *idx, Double_t v) |
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void | SetBinContent (Long64_t bin, Double_t v) |
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void | SetBinError2 (Long64_t bin, Double_t e2) |
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void | Sumw2 () |
| Enable calculation of errors. More...
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virtual | ~THnBase () |
| Destruct a THnBase. More...
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void | Add (const THnBase *h, Double_t c=1.) |
| Add contents of h scaled by c to this histogram: this = this + c * h Note that if h has Sumw2 set, Sumw2 is automatically called for this if not already set. More...
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void | Add (const TH1 *hist, Double_t c=1.) |
| Fill the THnBase with the bins of hist that have content or error != 0. More...
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void | AddBinContent (const Int_t *x, Double_t v=1.) |
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void | Browse (TBrowser *b) |
| Browse a THnSparse: create an entry (ROOT::THnSparseBrowsable) for each dimension. More...
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void | CalculateErrors (Bool_t calc=kTRUE) |
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Double_t | ComputeIntegral () |
| Calculate the integral of the histogram. More...
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void | Divide (const THnBase *h) |
| Divide this histogram by h this = this/(h) Note that if h has Sumw2 set, Sumw2 is automatically called for this if not already set. More...
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void | Divide (const THnBase *h1, const THnBase *h2, Double_t c1=1., Double_t c2=1., Option_t *option="") |
| Replace contents of this histogram by multiplication of h1 by h2 this = (c1*h1)/(c2*h2) Note that if h1 or h2 have Sumw2 set, Sumw2 is automatically called for this if not already set. More...
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Long64_t | Fill (const Double_t *x, Double_t w=1.) |
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Long64_t | Fill (const char *name[], Double_t w=1.) |
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TFitResultPtr | Fit (TF1 *f1, Option_t *option="", Option_t *goption="") |
| Fit a THnSparse with function f. More...
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TAxis * | GetAxis (Int_t dim) const |
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Double_t | GetBinContent (const Int_t *idx) const |
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Double_t | GetBinError (const Int_t *idx) const |
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Double_t | GetBinError (Long64_t linidx) const |
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Bool_t | GetCalculateErrors () const |
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Double_t | GetEntries () const |
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TObjArray * | GetListOfAxes () |
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const TObjArray * | GetListOfAxes () const |
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TList * | GetListOfFunctions () |
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Int_t | GetNdimensions () const |
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void | GetRandom (Double_t *rand, Bool_t subBinRandom=kTRUE) |
| Generate an n-dimensional random tuple based on the histogrammed distribution. More...
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Double_t | GetSumw () const |
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Double_t | GetSumw2 () const |
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Double_t | GetSumwx (Int_t dim) const |
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Double_t | GetSumwx2 (Int_t dim) const |
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Double_t | GetWeightSum () const |
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Bool_t | IsFolder () const |
| Returns kTRUE in case object contains browsable objects (like containers or lists of other objects). More...
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Bool_t | IsInRange (Int_t *coord) const |
| Check whether bin coord is in range, as defined by TAxis::SetRange(). More...
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Long64_t | Merge (TCollection *list) |
| Merge this with a list of THnBase's. More...
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void | Multiply (const THnBase *h) |
| Multiply this histogram by histogram h this = this * h Note that if h has Sumw2 set, Sumw2 is automatically called for this if not already set. More...
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void | Multiply (TF1 *f, Double_t c=1.) |
| Performs the operation: this = this*c*f1 if errors are defined, errors are also recalculated. More...
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void | Print (Option_t *option="") const |
| Print a THnBase. More...
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void | PrintBin (Int_t *coord, Option_t *options) const |
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void | PrintBin (Long64_t idx, Option_t *options) const |
| Print bin with linex index "idx". More...
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void | PrintEntries (Long64_t from=0, Long64_t howmany=-1, Option_t *options=0) const |
| Print "howmany" entries starting at "from". More...
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TH1D * | Projection (Int_t xDim, Option_t *option="") const |
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TH2D * | Projection (Int_t yDim, Int_t xDim, Option_t *option="") const |
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TH3D * | Projection (Int_t xDim, Int_t yDim, Int_t zDim, Option_t *option="") const |
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THnBase * | ProjectionND (Int_t ndim, const Int_t *dim, Option_t *option="") const |
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void | RebinnedAdd (const THnBase *h, Double_t c=1.) |
| Add contents of h scaled by c to this histogram: this = this + c * h Note that if h has Sumw2 set, Sumw2 is automatically called for this if not already set. More...
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void | Scale (Double_t c) |
| Scale contents and errors of this histogram by c: this = this * c It does not modify the histogram's number of entries. More...
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void | SetBinContent (const Int_t *idx, Double_t v) |
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void | SetBinEdges (Int_t idim, const Double_t *bins) |
| Set the axis # of bins and bin limits on dimension idim. More...
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void | SetBinError (const Int_t *idx, Double_t e) |
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void | SetBinError (Long64_t bin, Double_t e) |
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void | SetEntries (Double_t entries) |
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void | SetTitle (const char *title) |
| Change (i.e. More...
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| TNamed () |
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| TNamed (const char *name, const char *title) |
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| TNamed (const TString &name, const TString &title) |
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| TNamed (const TNamed &named) |
| TNamed copy ctor. More...
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virtual | ~TNamed () |
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virtual void | Clear (Option_t *option="") |
| Set name and title to empty strings (""). More...
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virtual TObject * | Clone (const char *newname="") const |
| Make a clone of an object using the Streamer facility. More...
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virtual Int_t | Compare (const TObject *obj) const |
| Compare two TNamed objects. More...
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virtual void | Copy (TObject &named) const |
| Copy this to obj. More...
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virtual void | FillBuffer (char *&buffer) |
| Encode TNamed into output buffer. More...
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virtual const char * | GetName () const |
| Returns name of object. More...
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virtual const char * | GetTitle () const |
| Returns title of object. More...
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virtual ULong_t | Hash () const |
| Return hash value for this object. More...
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virtual Bool_t | IsSortable () const |
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virtual void | ls (Option_t *option="") const |
| List TNamed name and title. More...
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TNamed & | operator= (const TNamed &rhs) |
| TNamed assignment operator. More...
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virtual void | SetName (const char *name) |
| Set the name of the TNamed. More...
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virtual void | SetNameTitle (const char *name, const char *title) |
| Set all the TNamed parameters (name and title). More...
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virtual Int_t | Sizeof () const |
| Return size of the TNamed part of the TObject. More...
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| TObject () |
| TObject constructor. More...
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| TObject (const TObject &object) |
| TObject copy ctor. More...
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virtual | ~TObject () |
| TObject destructor. More...
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void | AbstractMethod (const char *method) const |
| Use this method to implement an "abstract" method that you don't want to leave purely abstract. More...
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virtual void | AppendPad (Option_t *option="") |
| Append graphics object to current pad. More...
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virtual const char * | ClassName () const |
| Returns name of class to which the object belongs. More...
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virtual void | Delete (Option_t *option="") |
| Delete this object. More...
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virtual Int_t | DistancetoPrimitive (Int_t px, Int_t py) |
| Computes distance from point (px,py) to the object. More...
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virtual void | Draw (Option_t *option="") |
| Default Draw method for all objects. More...
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virtual void | DrawClass () const |
| Draw class inheritance tree of the class to which this object belongs. More...
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virtual TObject * | DrawClone (Option_t *option="") const |
| Draw a clone of this object in the current selected pad for instance with: gROOT->SetSelectedPad(gPad) . More...
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virtual void | Dump () const |
| Dump contents of object on stdout. More...
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virtual void | Error (const char *method, const char *msgfmt,...) const |
| Issue error message. More...
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virtual void | Execute (const char *method, const char *params, Int_t *error=0) |
| Execute method on this object with the given parameter string, e.g. More...
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virtual void | Execute (TMethod *method, TObjArray *params, Int_t *error=0) |
| Execute method on this object with parameters stored in the TObjArray. More...
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virtual void | ExecuteEvent (Int_t event, Int_t px, Int_t py) |
| Execute action corresponding to an event at (px,py). More...
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virtual void | Fatal (const char *method, const char *msgfmt,...) const |
| Issue fatal error message. More...
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virtual TObject * | FindObject (const char *name) const |
| Must be redefined in derived classes. More...
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virtual TObject * | FindObject (const TObject *obj) const |
| Must be redefined in derived classes. More...
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virtual Option_t * | GetDrawOption () const |
| Get option used by the graphics system to draw this object. More...
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virtual const char * | GetIconName () const |
| Returns mime type name of object. More...
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virtual char * | GetObjectInfo (Int_t px, Int_t py) const |
| Returns string containing info about the object at position (px,py). More...
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virtual Option_t * | GetOption () const |
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virtual UInt_t | GetUniqueID () const |
| Return the unique object id. More...
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virtual Bool_t | HandleTimer (TTimer *timer) |
| Execute action in response of a timer timing out. More...
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virtual void | Info (const char *method, const char *msgfmt,...) const |
| Issue info message. More...
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virtual Bool_t | InheritsFrom (const char *classname) const |
| Returns kTRUE if object inherits from class "classname". More...
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virtual Bool_t | InheritsFrom (const TClass *cl) const |
| Returns kTRUE if object inherits from TClass cl. More...
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virtual void | Inspect () const |
| Dump contents of this object in a graphics canvas. More...
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void | InvertBit (UInt_t f) |
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virtual Bool_t | IsEqual (const TObject *obj) const |
| Default equal comparison (objects are equal if they have the same address in memory). More...
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Bool_t | IsOnHeap () const |
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Bool_t | IsZombie () const |
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void | MayNotUse (const char *method) const |
| Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary). More...
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virtual Bool_t | Notify () |
| This method must be overridden to handle object notification. More...
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void | Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const |
| Use this method to declare a method obsolete. More...
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void | operator delete (void *ptr) |
| Operator delete. More...
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void | operator delete[] (void *ptr) |
| Operator delete []. More...
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void * | operator new (size_t sz) |
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void * | operator new (size_t sz, void *vp) |
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void * | operator new[] (size_t sz) |
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void * | operator new[] (size_t sz, void *vp) |
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TObject & | operator= (const TObject &rhs) |
| TObject assignment operator. More...
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virtual void | Paint (Option_t *option="") |
| This method must be overridden if a class wants to paint itself. More...
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virtual void | Pop () |
| Pop on object drawn in a pad to the top of the display list. More...
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virtual Int_t | Read (const char *name) |
| Read contents of object with specified name from the current directory. More...
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virtual void | RecursiveRemove (TObject *obj) |
| Recursively remove this object from a list. More...
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void | ResetBit (UInt_t f) |
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virtual void | SaveAs (const char *filename="", Option_t *option="") const |
| Save this object in the file specified by filename. More...
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virtual void | SavePrimitive (std::ostream &out, Option_t *option="") |
| Save a primitive as a C++ statement(s) on output stream "out". More...
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void | SetBit (UInt_t f, Bool_t set) |
| Set or unset the user status bits as specified in f. More...
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void | SetBit (UInt_t f) |
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virtual void | SetDrawOption (Option_t *option="") |
| Set drawing option for object. More...
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virtual void | SetUniqueID (UInt_t uid) |
| Set the unique object id. More...
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virtual void | SysError (const char *method, const char *msgfmt,...) const |
| Issue system error message. More...
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Bool_t | TestBit (UInt_t f) const |
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Int_t | TestBits (UInt_t f) const |
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virtual void | UseCurrentStyle () |
| Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked. More...
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virtual void | Warning (const char *method, const char *msgfmt,...) const |
| Issue warning message. More...
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virtual Int_t | Write (const char *name=0, Int_t option=0, Int_t bufsize=0) |
| Write this object to the current directory. More...
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virtual Int_t | Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const |
| Write this object to the current directory. More...
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| THn () |
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| THn (const char *name, const char *title, Int_t dim, const Int_t *nbins, const Double_t *xmin, const Double_t *xmax) |
| Construct a THn. More...
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void | AllocCoordBuf () const |
| Create the coordinate buffer. More...
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void | InitStorage (Int_t *nbins, Int_t chunkSize) |
| Initialize the storage of a histogram created via Init() More...
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| THnBase () |
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| THnBase (const char *name, const char *title, Int_t dim, const Int_t *nbins, const Double_t *xmin, const Double_t *xmax) |
| Construct a THnBase with "dim" dimensions, "nbins" holds the number of bins for each dimension; "xmin" and "xmax" the minimal and maximal value for each dimension. More...
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void | AddInternal (const THnBase *h, Double_t c, Bool_t rebinned) |
| Add() implementation for both rebinned histograms and those with identical binning. More...
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Bool_t | CheckConsistency (const THnBase *h, const char *tag) const |
| Consistency check on (some of) the parameters of two histograms (for operations). More...
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THnBase * | CloneEmpty (const char *name, const char *title, const TObjArray *axes, Bool_t keepTargetAxis) const |
| Create a new THnBase object that is of the same type as *this, but with dimensions and bins given by axes. More...
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TH1 * | CreateHist (const char *name, const char *title, const TObjArray *axes, Bool_t keepTargetAxis) const |
| Create an empty histogram with name and title with a given set of axes. More...
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void | FillBinBase (Double_t w) |
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void | Init (const char *name, const char *title, const TObjArray *axes, Bool_t keepTargetAxis, Int_t chunkSize=1024 *16) |
| Initialize axes and name. More...
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Bool_t | PrintBin (Long64_t idx, Int_t *coord, Option_t *options) const |
| Print one bin. More...
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TObject * | ProjectionAny (Int_t ndim, const Int_t *dim, Bool_t wantNDim, Option_t *option="") const |
| Project all bins into a ndim-dimensional THn / THnSparse (whatever *this is) or if (ndim < 4 and !wantNDim) a TH1/2/3 histogram, keeping only axes in dim (specifying ndim dimensions). More...
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THnBase * | RebinBase (Int_t group) const |
| Combine the content of "group" neighboring bins into a new bin and return the resulting THnBase. More...
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THnBase * | RebinBase (const Int_t *group) const |
| Combine the content of "group" neighboring bins for each dimension into a new bin and return the resulting THnBase. More...
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virtual void | Reserve (Long64_t) |
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void | ResetBase (Option_t *option="") |
| Clear the histogram. More...
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virtual void | SetFilledBins (Long64_t) |
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void | UpdateXStat (const Double_t *x, Double_t w=1.) |
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virtual void | DoError (int level, const char *location, const char *fmt, va_list va) const |
| Interface to ErrorHandler (protected). More...
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void | MakeZombie () |
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