library: libRooFit #include "RooSimPdfBuilder.h"

# RooSimPdfBuilder

class description - source file - inheritance tree (.pdf)

## class RooSimPdfBuilder : public TObject

| Inheritance Chart:

`TObject`

<-

`RooSimPdfBuilder`

        private:

                           RooSimPdfBuilder(const RooSimPdfBuilder&)

        public:

                                 RooSimPdfBuilder(const RooArgSet& pdfProtoList)
                                 ~RooSimPdfBuilder()
                            void addSpecializations(const RooArgSet& specSet)
          const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooArgSet& dependents, const RooArgSet* auxSplitCats = 0, Bool_t verbose = kFALSE) const
          const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooAbsData* dataSet, const RooArgSet& auxSplitCats, Bool_t verbose = kFALSE) const
          const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooArgSet& dependents, const RooArgSet& auxSplitCats, Bool_t verbose = kFALSE) const
          const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooAbsData* dataSet, const RooArgSet* auxSplitCats = 0, Bool_t verbose = kFALSE) const
                  static TClass* Class()
                      RooArgSet* createProtoBuildConfig()
                 virtual TClass* IsA() const
                    virtual void ShowMembers(TMemberInspector& insp, char* parent)
                const RooArgSet& splitLeafList() const
                    virtual void Streamer(TBuffer& b)
                            void StreamerNVirtual(TBuffer& b)

### Data Members

        protected:

          RooArgSet _protoPdfSet            Set of prototype PDFS
          RooArgSet _compSplitCatSet        List of owned composite splitting categories
          RooArgSet _splitNodeList          List of owned split nodes
              TList _retiredCustomizerList  Retired customizer from previous builds (own their PDF branch nodes)

## Class Description

`RooSimPdfBuilder` is a powerful tool to build `RooSimultaneous` PDFs that are defined in terms component PDFs that are identical in structure, but have different parameters.

## Example

The following example demonstrates the essence of `RooSimPdfBuilder`: Given a dataset D with a `RooRealVar X` and a `RooCategory C` that has state C1 and C2.

- We want to fit the distribution of `X` with a Gaussian+ArgusBG PDF,
- We want to fit the data subsets `D(C==C1)` and `D(C==C2)` separately and simultaneously.
- The PDFs to fit data subsets D_C1 and D_C2 are identical except for
  - the kappa parameter of the ArgusBG PDF and
  - the sigma parameter of the gaussian PDF
  where each PDF will have its own copy of the parameter

Coding this example directly with RooFit classes gives (we assume dataset D and variables C and X have been declared previously)

     RooRealVar m("m","mean of gaussian",-10,10) ;
     RooRealVar s_C1("s_C1","sigma of gaussian C1",0,20) ;
     RooRealVar s_C2("s_C2","sigma of gaussian C2",0,20) ;
     RooGaussian gauss_C1("gauss_C1","gaussian C1",X,m,s_C1) ;
     RooGaussian gauss_C2("gauss_C2","gaussian C2",X,m,s_C2) ;

     RooRealVar k_C1("k_C1","ArgusBG kappa parameter C1",-50,0) ;
     RooRealVar k_C2("k_C2","ArgusBG kappa parameter C2",-50,0) ;
     RooRealVar xm("xm","ArgusBG cutoff point",5.29) ;
     RooArgusBG argus_C1("argus_C1","argus background C1",X,k_C1,xm) ;
     RooArgusBG argus_C2("argus_C2","argus background C2",X,k_C2,xm) ;

     RooRealVar gfrac("gfrac","fraction of gaussian",0.,1.) ;
     RooAddPdf pdf_C1("pdf_C1","gauss+argus_C1",RooArgList(gauss_C1,argus_C1),gfrac) ;
     RooAddPdf pdf_C2("pdf_C2","gauss+argus_C2",RooArgList(gauss_C2,argus_C2),gfrac) ;

     RooSimultaneous simPdf("simPdf","simPdf",C) ;
     simPdf.addPdf(pdf_C1,"C1") ;
     simPdf.addPdf(pdf_C2,"C2") ;

Coding this example with RooSimPdfBuilder gives

     RooRealVar m("m","mean of gaussian",-10,10) ;
     RooRealVar s("s","sigma of gaussian",0,20) ;
     RooGaussian gauss("gauss","gaussian",X,m,s) ;

     RooRealVar k("k","ArgusBG kappa parameter",-50,0) ;
     RooRealVar xm("xm","ArgusBG cutoff point",5.29) ;
     RooArgusBG argus("argus","argus background",X,k,xm) ;

     RooRealVar gfrac("gfrac","fraction of gaussian",0.,1.) ;
     RooAddPdf pdf("pdf","gauss+argus",RooArgList(gauss,argus),gfrac) ;

     RooSimPdfBuilder builder(pdf) ;
     RooArgSet* config = builder.createProtoBuildConfig() ;
     (*config)["physModels"] = "pdf" ;      // Name of the PDF we are going to work with
     (*config)["splitCats"]  = "C" ;        // Category used to differentiate sub-datasets
     (*config)["pdf"]        = "C : k,s" ;  // Prescription to taylor PDF parameters k and s
                                            // for each data subset designated by C states
     RooSimultaneous* simPdf = builder.buildPdf(*config,&D) ;

The above snippet of code demonstrates the concept of `RooSimPdfBuilder`: the user defines a single 'prototype' PDF that defines the structure of all PDF components of the `RooSimultaneous` PDF to be built. `RooSimPdfBuilder` then takes this prototype and replicates it as a component PDF for each state of the C index category.

In the above example RooSimPdfBuilder will first replicate `k` and `s` into `k_C1,k_C2` and `s_C1,s_C2`, as prescribed in the configuration. Then it will recursively replicate all PDF nodes that depend on the 'split' parameter nodes: `gauss` into `gauss_C1,C2`, `argus` into `argus_C1,C2` and finally `pdf` into `pdf_C1,pdf_C2`. When PDFs for all states of C have been replicated they are assembled into a `RooSimultaneous` PDF, which is returned by the `buildPdf()` method.

Although in this very simple example the use of `RooSimPdfBuilder` doesn't reduce the amount of code much, it is already easier to read and maintain because there is no duplicate code. As the complexity of the `RooSimultaneous` to be built increases, the advantages of `RooSimPdfBuilder` will become more and more apparent.

## Builder configuration rules for a single prototype PDF

Each builder configuration needs at minumum two lines, `physModels` and `splitCats`, which identify the ingredients of the build. In this section we only explain the building rules for builds from a single prototype PDF. In that case the `physModels` line always reads

      physModels = {pdfName}

The second line, `splitCats`, indicates which categories are going to be used to differentiate the various subsets of the 'master' input data set. You can enter a single category here, or multiple if necessary:

     splitCats = {catName} [{catName} ...]

All listed splitcats must be `RooCategories` that appear in the dataset provided to `RooSimPdfBuilder::buildPdf()`

The parameter splitting prescriptions, the essence of each build configuration can be supplied in a third line carrying the name of the pdf listed in `physModels`

     pdfName = {splitCat} : {parameter} [,{parameter},....]

Each pdf can have only one line with splitting rules, but multiple rules can be supplied in each line, e.g.

     pdfName = {splitCat} : {parameter} [,{parameter},....]
               {splitCat} : {parameter} [,{parameter},....]

Conversely, each parameter can only have one splitting prescription, but it may be split by multiple categories, e.g.

     pdfName = {splitCat1},{splitCat2} : {parameter}

instructs `RooSimPdfBuilder` to build a `RooSuperCategory` of `{splitCat1}` and `{splitCat2}` and split `{parameter}` with that `RooSuperCategory`

Here is an example of a builder configuration that uses several of the options discussed above:

       physModels = pdf
       splitCats  = tagCat runBlock
       pdf        = tagCat          : signalRes,bkgRes
                    runBlock        : fudgeFactor
                    tagCat,runBlock : kludgeParam

## How to enter configuration data

The prototype builder configuration returned by `RooSimPdfBuilder::createProtoBuildConfig()` is a pointer to a `RooArgSet` filled with initially blank `RooStringVars` named `physModels,splitCats` and one additional for each PDF supplied to the `RooSimPdfBuilders` constructor (with the same name)

In macro code, the easiest way to assign new values to these `RooStringVars` is to use `RooArgSet`s array operator and the `RooStringVar`s assignment operator, e.g.

     (*config)["physModels"] = "Blah" ;

To enter multiple splitting rules simply separate consecutive rules by whitespace (not newlines), e.g.

     (*config)["physModels"] = "Blah " // << note trailing space here
                              "Blah 2" ;

In this example, the C++ compiler will concatenate the two string literals (without inserting any whitespace), so the extra space after 'Blah' is important here.

Alternatively, you can read the configuration from an ASCII file, as you can for any `RooArgSet` using `RooArgSet::readFromFile()`. In that case the ASCII file can follow the syntax of the examples above and the '`\\`' line continuation sequence can be used to fold a long splitting rule over multiple lines.

     RooArgSet* config = builder.createProtoBuildConfig() ;
     config->readFromFile("config.txt") ;

     --- config.txt ----------------
     physModels = pdf
     splitCats  = tagCat
     pdf        = tagCat : bogusPar
     -------------------------------

## Working with multiple prototype PDFs

It is also possible to build a `RooSimultaneous` PDF from multiple PDF prototypes. This is appropriate for cases where the input prototype PDF would otherwise be a `RooSimultaneous` PDF by itself. In such cases we don't feed a single `RooSimultaneous` PDF into `RooSimPdfBuilder`, instead we feed it its ingredients and add a prescription to the builder configuration that corresponds to the PDF-category state mapping of the prototype `RooSimultaneous`.

The constructor of the `RooSimPdfBuilder` will look as follows:

      RooSimPdfBuilder builder(RooArgSet(pdfA,pdfB,...)) ;

The `physModels` line is now expanded to carry the pdf->state mapping information that the prototype `RooSimultaneous` would have. I.e.

     physModels = mode : pdfA=modeA  pdfB=modeB

is equivalent to a prototype `RooSimultaneous` constructed as

     RooSimultanous simPdf("simPdf","simPdf",mode);
     simPdf.addPdf(pdfA,"modeA") ;
     simPdf.addPdf(pdfB,"modeB") ;

The rest of the builder configuration works the same, except that each prototype PDF now has its own set of splitting rules, e.g.

     physModels = mode : pdfA=modeA  pdfB=modeB
     splitCats  = tagCat
     pdfA       = tagCat : bogusPar
     pdfB       = tagCat : fudgeFactor

Please note that

- The master index category ('mode' above) doesn't have to be listed in `splitCats`, this is implicit.
- The number of splitting prescriptions goes by the number of prototype PDFs and not by the number of states of the master index category (mode in the above and below example).

In the following case:

        physModels = mode : pdfA=modeA  pdfB=modeB  pdfA=modeC  pdfB=modeD

there are still only 2 sets of splitting rules: one for `pdfA` and one for `pdfB`. However, you can differentiate between `modeA` and `modeC` in the above example. The technique is to use `mode` as splitting category, e.g.

        physModels = mode : pdfA=modeA  pdfB=modeB  pdfA=modeC  pdfB=modeD
        splitCats = tagCat
        pdfA      = tagCat : bogusPar
                    mode   : funnyPar
        pdfB      = mode   : kludgeFactor

will result in an individual set of `funnyPar` parameters for `modeA` and `modeC` labeled `funnyPar_modeA` and `funnyPar_modeB` and an individual set of kludgeFactor parameters for `pdfB`, `kludgeFactor_modeB` and `kludgeFactor_modeD`. Please note that for splits in the master index category (mode) only the applicable states are built (A,C for `pdfA`, B,D for `pdfB`)

## Advanced options

#### Partial splits

You can request to limit the list of states of each splitCat that will be considered in the build. This limitation is requested in the each build as follows:

     splitCats = tagCat(Lep,Kao) RunBlock(Run1)

In this example the splitting of `tagCat` is limited to states `Lep,Kao` and the splitting of `runBlock` is limited to `Run1`. The splits apply globally to each build, i.e. every parameter split requested in this build will be limited according to these specifications.

NB: Partial builds have no pdf associated with the unbuilt states of the limited splits. Running such a pdf on a dataset that contains data with unbuilt states will result in this data being ignored completely.

#### Non-trivial splits

It is possible to make non-trivial parameter splits with `RooSimPdfBuilder`. Trivial splits are considered simple splits in one (fundamental) category in the dataset or a split in a `RooSuperCategory` 'product' of multiple fundamental categories in the dataset. Non-trivial splits can be performed using an intermediate 'category function' (`RooMappedCategory, RooGenericCategory,RooThresholdCategory` etc), i.e. any `RooAbsCategory` derived objects that calculates its output as function of one or more input `RooRealVars` and/or `RooCategories`.

Such 'function categories' objects must be constructed by the user prior to building the PDF. In the `RooSimPdfBuilder::buildPdf()` function these objects can be passed in an optional `RooArgSet` called 'auxiliary categories':

       const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooAbsData* dataSet,
                                       const RooArgSet& auxSplitCats, Bool_t verbose=kFALSE) {
                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Objects passed in this argset can subsequently be used in the build configuration, e.g.

     RooMappedCategory tagMap("tagMap","Mapped tagging category",tagCat,"CutBased") ;
     tagMap.map("Lep","CutBased") ;
     tagMap.map("Kao","CutBased") ;
     tagMap.map("NT*","NeuralNet") ;
     ...
     builder.buildPdf(config,D,tagMap) ;
                              ^^^^^^
    <Contents of config>
       physModels = pdf
       splitCats  = tagCat runBlock
       pdf        = tagCat          : signalRes
                    tagMap          : fudgeFactor
                    ^^^^^^

In the above example `signalRes` will be split in `signalRes_Kao,signalRes_Lep, signalRes_NT1,signalRes_NT2`, while `fudgeFactor` will be split in `fudgeFactor_CutBased` and `fudgeFactor_NeuralNet`.

Category functions passed in the auxSplitCats `RooArgSet` can be used regularly in the splitting configuration. They should not be listed in `splitCats`, but must be able to be expressed completely in terms of the `splitCats` that are listed.

#### Multiple connected builds

Sometimes you want to build multiple PDFs for independent consecutive fits that share some of their parameters. For example, we have two prototype PDFs `pdfA(x;p,q)` and `pdfB(x;p,r)` that have a common parameter `p`. We want to build a `RooSimultaneous` for both `pdfA` and `B`, which involves a split of parameter `p` and we would like to build the simultaneous pdfs simA and `simB` such that still share their (now split) parameters `p_XXX`. This is accomplished by letting a single instance of `RooSimPdfBuilder` handle the builds of both `pdfA` and `pdfB`, as illustrated in this example:

     RooSimPdfBuilder builder(RooArgSet(pdfA,pdfB)) ;

     RooArgSet* configA = builder.createProtoBuildConfig() ;
     (*configA)["physModels"] = "pdfA" ;
     (*configA)["splitCats"]  = "C" ;
     (*configA)["pdf"]        = "C : p" ;
     RooSimultaneous* simA = builder.buildPdf(*configA,&D) ;

     RooArgSet* configB = builder.createProtoBuildConfig() ;
     (*configA)["physModels"] = "pdfB" ;
     (*configA)["splitCats"]  = "C" ;
     (*configA)["pdf"]        = "C : p" ;
     RooSimultaneous* simB = builder.buildPdf(*configB,&D) ;

## Ownership of constructed PDFs

The `RooSimPdfBuilder` instance owns all the objects it creates, including the top-level `RooSimultaneous` returned by `buildPdf()`. Therefore the builder instance should exist as long as the constructed PDFs needs to exist.

###

     RooSimPdfBuilder(const RooArgSet& protoPdfSet) :
      _protoPdfSet(protoPdfSet)

    RooArgSet* createProtoBuildConfig()

     Make RooArgSet of configuration objects

    void addSpecializations(const RooArgSet& specSet)

    const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooArgSet& dependents,
    					    const RooArgSet* auxSplitCats, Bool_t verbose)

     Initialize needed components

     ~RooSimPdfBuilder()

    Inline Functions

            const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooAbsData* dataSet, const RooArgSet& auxSplitCats, Bool_t verbose = kFALSE) const
            const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooArgSet& dependents, const RooArgSet& auxSplitCats, Bool_t verbose = kFALSE) const
            const RooSimultaneous* buildPdf(const RooArgSet& buildConfig, const RooAbsData* dataSet, const RooArgSet* auxSplitCats = 0, Bool_t verbose = kFALSE) const
                  const RooArgSet& splitLeafList() const
                  RooSimPdfBuilder RooSimPdfBuilder(const RooSimPdfBuilder&)
                           TClass* Class()
                           TClass* IsA() const
                              void ShowMembers(TMemberInspector& insp, char* parent)
                              void Streamer(TBuffer& b)
                              void StreamerNVirtual(TBuffer& b)

    Last update: Tue Jun 28 18:15:11 2005

    Copyright  (c) 2000-2005, Regents of the University of California          *