# T M V A Regression Application¶

This macro provides a simple example on how to use the trained regression MVAs within an analysis module

• Project : TMVA - a Root-integrated toolkit for multivariate data analysis
• Package : TMVA
• Executable: TMVARegressionApplication

Author: Andreas Hoecker
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Saturday, September 18, 2021 at 09:51 AM.

In :
%%cpp -d
#include <cstdlib>
#include <vector>
#include <iostream>
#include <map>
#include <string>

#include "TFile.h"
#include "TTree.h"
#include "TString.h"
#include "TSystem.h"
#include "TROOT.h"
#include "TStopwatch.h"

#include "TMVA/Tools.h"

using namespace TMVA;


Arguments are defined.

In :
TString myMethodList = "";


In :
TMVA::Tools::Instance();


Default mva methods to be trained + tested

In :
std::map<std::string,int> Use;


--- mutidimensional likelihood and nearest-neighbour methods

In :
Use["PDERS"]           = 0;
Use["PDEFoam"]         = 1;
Use["KNN"]             = 1;


--- Linear Discriminant Analysis

In :
Use["LD"]              = 1;


--- Function Discriminant analysis

In :
Use["FDA_GA"]          = 0;
Use["FDA_MC"]          = 0;
Use["FDA_MT"]          = 0;
Use["FDA_GAMT"]        = 0;


--- Neural Network

In :
Use["MLP"] = 0;
#ifdef R__HAS_TMVACPU
Use["DNN_CPU"] = 1;
#else
Use["DNN_CPU"] = 0;
#endif


--- Support Vector Machine

In :
Use["SVM"]             = 0;


--- Boosted Decision Trees

In :
Use["BDT"]             = 0;
Use["BDTG"]            = 1;


In :
std::cout << std::endl;
std::cout << "==> Start TMVARegressionApplication" << std::endl;

==> Start TMVARegressionApplication


Select methods (don't look at this code - not of interest)

In :
if (myMethodList != "") {
for (std::map<std::string,int>::iterator it = Use.begin(); it != Use.end(); it++) it->second = 0;

std::vector<TString> mlist = gTools().SplitString( myMethodList, ',' );
for (UInt_t i=0; i<mlist.size(); i++) {
std::string regMethod(mlist[i]);

if (Use.find(regMethod) == Use.end()) {
std::cout << "Method \"" << regMethod << "\" not known in TMVA under this name. Choose among the following:" << std::endl;
for (std::map<std::string,int>::iterator it = Use.begin(); it != Use.end(); it++) std::cout << it->first << " ";
std::cout << std::endl;
return;
}
Use[regMethod] = 1;
}
}


In :
TMVA::Reader *reader = new TMVA::Reader( "!Color:!Silent" );


Create a set of variables and declare them to the reader

• the variable names MUST corresponds in name and type to those given in the weight file(s) used
In :
Float_t var1, var2;


Spectator variables declared in the training have to be added to the reader, too

In :
Float_t spec1,spec2;


--- book the mva methods

In :
TString dir    = "dataset/weights/";
TString prefix = "TMVARegression";


Book method(s)

In :
for (std::map<std::string,int>::iterator it = Use.begin(); it != Use.end(); it++) {
if (it->second) {
TString methodName = it->first + " method";
TString weightfile = dir + prefix + "_" + TString(it->first) + ".weights.xml";
}
}

                         : Booking "BDTG method" of type "BDT" from dataset/weights/TMVARegression_BDTG.weights.xml.
: Booked classifier "BDTG" of type: "BDT"
: Booking "DNN_CPU method" of type "DL" from dataset/weights/TMVARegression_DNN_CPU.weights.xml.
: Booked classifier "DNN_CPU" of type: "DL"
: Booking "KNN method" of type "KNN" from dataset/weights/TMVARegression_KNN.weights.xml.
: Creating kd-tree with 1000 events
: Computing scale factor for 1d distributions: (ifrac, bottom, top) = (80%, 10%, 90%)
<HEADER> ModulekNN                : Optimizing tree for 2 variables with 1000 values
: <Fill> Class 1 has     1000 events
: Booked classifier "KNN" of type: "KNN"
: Booking "LD method" of type "LD" from dataset/weights/TMVARegression_LD.weights.xml.
: Booked classifier "LD" of type: "LD"
: Booking "PDEFoam method" of type "PDEFoam" from dataset/weights/TMVARegression_PDEFoam.weights.xml.
: Read foams from file: dataset/weights/TMVARegression_PDEFoam.weights_foams.root
: Booked classifier "PDEFoam" of type: "PDEFoam"


Book output histograms

In :
TH1* hists;
Int_t nhists = -1;
for (std::map<std::string,int>::iterator it = Use.begin(); it != Use.end(); it++) {
TH1* h = new TH1F( it->first.c_str(), TString(it->first) + " method", 100, -100, 600 );
if (it->second) hists[++nhists] = h;
}
nhists++;


Prepare input tree (this must be replaced by your data source) in this example, there is a toy tree with signal and one with background events we'll later on use only the "signal" events for the test in this example.

In :
TFile *input(0);
TString fname = "./tmva_reg_example.root";
if (!gSystem->AccessPathName( fname )) {
input = TFile::Open( fname ); // check if file in local directory exists
}
else {
TFile::SetCacheFileDir(".");
}
if (!input) {
std::cout << "ERROR: could not open data file" << std::endl;
exit(1);
}
std::cout << "--- TMVARegressionApp        : Using input file: " << input->GetName() << std::endl;

--- TMVARegressionApp        : Using input file: ./files/tmva_reg_example.root

Info in <TFile::OpenFromCache>: using local cache copy of http://root.cern.ch/files/tmva_reg_example.root [./files/tmva_reg_example.root]


--- event loop

Prepare the tree

• here the variable names have to corresponds to your tree
• you can use the same variables as above which is slightly faster, but of course you can use different ones and copy the values inside the event loop
In :
TTree* theTree = (TTree*)input->Get("TreeR");
std::cout << "--- Select signal sample" << std::endl;

std::cout << "--- Processing: " << theTree->GetEntries() << " events" << std::endl;
TStopwatch sw;
sw.Start();
for (Long64_t ievt=0; ievt<theTree->GetEntries();ievt++) {

if (ievt%1000 == 0) {
std::cout << "--- ... Processing event: " << ievt << std::endl;
}

theTree->GetEntry(ievt);

// Retrieve the MVA target values (regression outputs) and fill into histograms
// NOTE: EvaluateRegression(..) returns a vector for multi-target regression

for (Int_t ih=0; ih<nhists; ih++) {
TString title = hists[ih]->GetTitle();
Float_t val = (reader->EvaluateRegression( title ));
hists[ih]->Fill( val );
}
}
sw.Stop();
std::cout << "--- End of event loop: "; sw.Print();

--- Select signal sample
--- Processing: 10000 events
--- ... Processing event: 0
: Rebuilding Dataset Default
--- ... Processing event: 1000
--- ... Processing event: 2000
--- ... Processing event: 3000
--- ... Processing event: 4000
--- ... Processing event: 5000
--- ... Processing event: 6000
--- ... Processing event: 7000
--- ... Processing event: 8000
--- ... Processing event: 9000
--- End of event loop: Real time 0:00:03, CP time 3.200


--- write histograms

In :
TFile *target  = new TFile( "TMVARegApp.root","RECREATE" );
for (Int_t ih=0; ih<nhists; ih++) hists[ih]->Write();
target->Close();

std::cout << "--- Created root file: \"" << target->GetName()
<< "\" containing the MVA output histograms" << std::endl;


--- Created root file: "TMVARegApp.root" containing the MVA output histograms