{
"cells": [
{
"cell_type": "markdown",
"id": "168de751",
"metadata": {},
"source": [
"# fitslicesy\n",
"Illustrates how to use the TH1::FitSlicesY function\n",
"It uses the TH2F histogram generated in macro hsimple.C\n",
"It invokes FitSlicesY and draw the fitted \"mean\" and \"sigma\"\n",
"in 2 sepate pads.\n",
"This macro shows also how to annotate a picture, change\n",
"some pad parameters.\n",
"\n",
"\n",
"\n",
"\n",
"**Author:** Rene Brun \n",
"This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, May 19, 2026 at 08:06 PM."
]
},
{
"cell_type": "markdown",
"id": "d68d7d8b",
"metadata": {},
"source": [
"Change some default parameters in the current style"
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "88f5e9bb",
"metadata": {
"collapsed": false,
"execution": {
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"shell.execute_reply": "2026-05-19T20:06:26.070575Z"
}
},
"outputs": [],
"source": [
"gStyle->SetLabelSize(0.06,\"x\");\n",
"gStyle->SetLabelSize(0.06,\"y\");\n",
"gStyle->SetFrameFillColor(38);\n",
"gStyle->SetTitleW(0.6);\n",
"gStyle->SetTitleH(0.1);"
]
},
{
"cell_type": "markdown",
"id": "99056698",
"metadata": {},
"source": [
"Connect the input file and get the 2-d histogram in memory"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "ccc1ac34",
"metadata": {
"collapsed": false,
"execution": {
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"shell.execute_reply": "2026-05-19T20:06:26.720471Z"
}
},
"outputs": [
{
"data": {
"text/html": [
"\n",
"\n",
"\n",
"
\n",
"\n",
"\n",
"\n"
],
"text/plain": [
""
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"TString dir = gROOT->GetTutorialDir();\n",
"dir.Append(\"/hsimple.C\");\n",
"dir.ReplaceAll(\"/./\",\"/\");\n",
"if (!gInterpreter->IsLoaded(dir.Data())) gInterpreter->LoadMacro(dir.Data());\n",
"TFile *hsimpleFile = (TFile*)gROOT->ProcessLineFast(\"hsimple(1)\");\n",
"if (!hsimpleFile) return;\n",
"TH2F *hpxpy = (TH2F*)hsimpleFile->Get(\"hpxpy\");"
]
},
{
"cell_type": "markdown",
"id": "67cb6cbd",
"metadata": {},
"source": [
"Create a canvas and divide it"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "2870d099",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:06:26.737324Z",
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"shell.execute_reply": "2026-05-19T20:06:26.960440Z"
}
},
"outputs": [
{
"name": "stderr",
"output_type": "stream",
"text": [
"Warning in : Deleting canvas with same name: c1\n"
]
}
],
"source": [
"TCanvas *c1 = new TCanvas(\"c1\",\"c1\",700,500);\n",
"c1->SetFillColor(42);\n",
"c1->Divide(2,1);\n",
"TPad *leftPad = (TPad*)c1->cd(1);;\n",
"leftPad->Divide(1,2);"
]
},
{
"cell_type": "markdown",
"id": "dfabda9b",
"metadata": {},
"source": [
"Draw 2-d original histogram"
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "f6aea917",
"metadata": {
"collapsed": false,
"execution": {
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"shell.execute_reply": "2026-05-19T20:06:27.186254Z"
}
},
"outputs": [],
"source": [
"leftPad->cd(1);\n",
"gPad->SetTopMargin(0.12);\n",
"gPad->SetFillColor(33);\n",
"hpxpy->Draw();\n",
"hpxpy->GetXaxis()->SetLabelSize(0.06);\n",
"hpxpy->GetYaxis()->SetLabelSize(0.06);\n",
"hpxpy->SetMarkerColor(kYellow);"
]
},
{
"cell_type": "markdown",
"id": "aa82775b",
"metadata": {},
"source": [
"Fit slices projected along Y fron bins in X [7,32] with more than 20 bins in Y filled"
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "a78e650d",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:06:27.219229Z",
"iopub.status.busy": "2026-05-19T20:06:27.219072Z",
"iopub.status.idle": "2026-05-19T20:06:27.557746Z",
"shell.execute_reply": "2026-05-19T20:06:27.557340Z"
}
},
"outputs": [],
"source": [
"hpxpy->FitSlicesY(nullptr,7,32,20);"
]
},
{
"cell_type": "markdown",
"id": "35075147",
"metadata": {},
"source": [
"Show fitted \"mean\" for each slice"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "771dc794",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:06:27.590437Z",
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"shell.execute_reply": "2026-05-19T20:06:27.803647Z"
}
},
"outputs": [],
"source": [
"leftPad->cd(2);\n",
"gPad->SetFillColor(33);\n",
"TH2F *hpxpy_0 = (TH2F*)hsimpleFile->Get(\"hpxpy_0\");\n",
"hpxpy_0->Draw();\n",
"TPad *rightPad = (TPad*)c1->cd(2);\n",
"rightPad->Divide(1,2);\n",
"rightPad->cd(1);\n",
"gPad->SetTopMargin(0.12);\n",
"gPad->SetLeftMargin(0.15);\n",
"gPad->SetFillColor(33);\n",
"TH2F *hpxpy_1 = (TH2F*)hsimpleFile->Get(\"hpxpy_1\");\n",
"hpxpy_1->Draw();"
]
},
{
"cell_type": "markdown",
"id": "01da599c",
"metadata": {},
"source": [
"Show fitted \"sigma\" for each slice"
]
},
{
"cell_type": "code",
"execution_count": 7,
"id": "2e7531dd",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:06:27.826231Z",
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"iopub.status.idle": "2026-05-19T20:06:28.028150Z",
"shell.execute_reply": "2026-05-19T20:06:28.027701Z"
}
},
"outputs": [],
"source": [
"rightPad->cd(2);\n",
"gPad->SetTopMargin(0.12);\n",
"gPad->SetLeftMargin(0.15);\n",
"gPad->SetFillColor(33);\n",
"TH2F *hpxpy_2 = (TH2F*)hsimpleFile->Get(\"hpxpy_2\");\n",
"hpxpy_2->SetMinimum(0.8);\n",
"hpxpy_2->Draw();"
]
},
{
"cell_type": "markdown",
"id": "dc1c3644",
"metadata": {},
"source": [
"attributes"
]
},
{
"cell_type": "code",
"execution_count": 8,
"id": "e5db1e07",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:06:28.036117Z",
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"shell.execute_reply": "2026-05-19T20:06:28.241855Z"
}
},
"outputs": [],
"source": [
"hpxpy_0->SetLineColor(5);\n",
"hpxpy_1->SetLineColor(5);\n",
"hpxpy_2->SetLineColor(5);\n",
"hpxpy_0->SetMarkerColor(2);\n",
"hpxpy_1->SetMarkerColor(2);\n",
"hpxpy_2->SetMarkerColor(2);\n",
"hpxpy_0->SetMarkerStyle(21);\n",
"hpxpy_1->SetMarkerStyle(21);\n",
"hpxpy_2->SetMarkerStyle(21);\n",
"hpxpy_0->SetMarkerSize(0.6);\n",
"hpxpy_1->SetMarkerSize(0.6);\n",
"hpxpy_2->SetMarkerSize(0.6);"
]
},
{
"cell_type": "markdown",
"id": "3c1f5fbd",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 9,
"id": "aa2cc288",
"metadata": {
"collapsed": false,
"execution": {
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"shell.execute_reply": "2026-05-19T20:06:28.483916Z"
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},
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"text/html": [
"\n",
"\n",
"\n",
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\n",
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"\n",
"\n"
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"metadata": {},
"output_type": "display_data"
}
],
"source": [
"%jsroot on\n",
"gROOT->GetListOfCanvases()->Draw()"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "ROOT C++",
"language": "c++",
"name": "root"
},
"language_info": {
"codemirror_mode": "text/x-c++src",
"file_extension": ".C",
"mimetype": " text/x-c++src",
"name": "c++"
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