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.L $ROOTSYS/tutorials/tree/drawsparse.C+Author: Axel Naumann
This notebook tutorial was automatically generated with ROOTBOOK-izer (Beta) from the macro found in the ROOT repository on Tuesday, January 17, 2017 at 02:42 PM.
In [1]:
%%cpp -d
#include "TParallelCoord.h"
#include "TParallelCoordVar.h"
#include "TROOT.h"
#include "TTree.h"
#include "TLeaf.h"
#include "THnSparse.h"
#include "TAxis.h"
#include "TCanvas.h"
#include "TRandom.h"
#include "TFile.h"
#include "TH3.h"
A helper function is created:
In [2]:
%%cpp -d
TTree* toTree(THnSparse* h)
{
// Creates a TTree and fills it with the coordinates of all
// filled bins. The tree will have one branch for each dimension,
// and one for the bin content.
Int_t dim = h->GetNdimensions();
TString name(h->GetName()); name += "_tree";
TString title(h->GetTitle()); title += " tree";
TTree* tree = new TTree(name, title);
Double_t* x = new Double_t[dim + 1];
memset(x, 0, sizeof(Double_t) * (dim + 1));
TString branchname;
for (Int_t d = 0; d < dim; ++d) {
if (branchname.Length())
branchname += ":";
TAxis* axis = h->GetAxis(d);
branchname += axis->GetName();
branchname += "/D";
}
tree->Branch("coord", x, branchname);
tree->Branch("bincontent", &x[dim], "bincontent/D");
Int_t *bins = new Int_t[dim];
for (Long64_t i = 0; i < h->GetNbins(); ++i) {
x[dim] = h->GetBinContent(i, bins);
for (Int_t d = 0; d < dim; ++d) {
x[d] = h->GetAxis(d)->GetBinCenter(bins[d]);
}
tree->Fill();
}
delete [] bins;
//delete [] x;
return tree;
}
A helper function is created:
In [3]:
%%cpp -d
void drawsparse_draw(THnSparse* h)
{
// Draw a THnSparse using TParallelCoord, creating a temporary TTree.
TTree* tree = toTree(h);
TString whatToDraw;
TIter iLeaf(tree->GetListOfLeaves());
const TLeaf* leaf = 0;
while ((leaf = (const TLeaf*)iLeaf())) {
if (whatToDraw.Length())
whatToDraw += ":";
whatToDraw += leaf->GetName();
}
tree->Draw(whatToDraw, "", "para");
TParallelCoord* parallelCoord = (TParallelCoord*)gPad->GetListOfPrimitives()->FindObject("ParaCoord");
TIter iVar(parallelCoord->GetVarList());
TParallelCoordVar* var = 0;
for (Int_t d = 0;(var = (TParallelCoordVar*) iVar()) && d < h->GetNdimensions(); ++d) {
TAxis* axis = h->GetAxis(d);
var->SetHistogramBinning(axis->GetNbins());
var->SetCurrentLimits(axis->GetXmin(), axis->GetXmax());
var->SetTitle(axis->GetTitle());
}
var->SetTitle("bin content");
}
Create a thnsparse and draw it.
In [4]:
const Int_t ndims = 8;
Int_t bins[ndims] = {10, 10, 5, 30, 10, 4, 18, 12};
Double_t xmin[ndims] = {-5., -10., -1000., -3., 0., 0., 0., 0.};
Double_t xmax[ndims] = {10., 70., 3000., 3., 5., 2., 2., 5.};
THnSparse* hs = new THnSparseD("hs", "Sparse Histogram", ndims, bins, xmin, xmax);
Fill it
In [5]:
Double_t x[ndims];
for (Long_t i = 0; i < 100000; ++i) {
for (Int_t d = 0; d < ndims; ++d) {
switch (d) {
case 0: x[d] = gRandom->Gaus()*2 + 3.; break;
case 1:
case 2:
case 3: x[d] = (x[d-1]*x[d-1] - 1.5)/1.5 + (0.5*gRandom->Rndm()); break;
default: x[d] = sin(gRandom->Gaus()*i/1000.) + 1.;
}
}
hs->Fill(x);
}
TFile* f = new TFile("drawsparse.root","RECREATE");
TCanvas* canv = new TCanvas("hDrawSparse", "Drawing a sparse hist");
canv->Divide(2);
Draw it
In [6]:
canv->cd(1);
drawsparse_draw(hs);
Project it
In [7]:
canv->cd(2);
TH3D* h3proj = hs->Projection(2, 3, 6);
h3proj->SetLineColor(kOrange);
h3proj->SetDirectory(0);
h3proj->Draw("lego1");
Save everything to a file
In [8]:
canv->Write();
hs->Write();
h3proj->Write();
delete f;
Draw all canvases
In [9]:
gROOT->GetListOfCanvases()->Draw()