{
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"# hist029_TRatioPlot_simple\n",
"Two histograms are set up and filled with random numbers. The constructor of `TRatioPlot`\n",
"takes the two histograms, name and title for the object, drawing options for the histograms\n",
"(`hist` and `E` in this case) and a drawing option for the output graph.\n",
"The histograms drawing options can be changed with `SetH1DrawOpt` and `SetH2DrawOpt`.\n",
"\n",
"\n",
"\n",
"\n",
"**Author:** Paul Gessinger \n",
"This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, May 19, 2026 at 08:12 PM."
]
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{
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"gStyle->SetOptStat(0);\n",
"auto C = new TCanvas(\"C\", \"A ratio example\");\n",
"auto h1 = new TH1D(\"h1\", \"TRatioPlot Example; x; y\", 50, 0, 10);\n",
"auto h2 = new TH1D(\"h2\", \"h2\", 50, 0, 10);\n",
"auto f1 = new TF1(\"f1\", \"exp(- x/[0] )\");\n",
"f1->SetParameter(0, 3);\n",
"h1->FillRandom(\"f1\", 1900);\n",
"h2->FillRandom(\"f1\", 2000);\n",
"h1->Sumw2();\n",
"h2->Scale(1.9 / 2.);\n",
"h2->SetLineColor(kRed);"
]
},
{
"cell_type": "markdown",
"id": "3860d559",
"metadata": {},
"source": [
"Create and draw the ratio plot"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "51c92ba8",
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"execution": {
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"shell.execute_reply": "2026-05-19T20:12:34.312674Z"
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"outputs": [],
"source": [
"auto rp = new TRatioPlot(h1, h2);\n",
"C->SetTicks(0, 1);\n",
"rp->Draw();\n",
"rp->GetLowYaxis()->SetNdivisions(505);"
]
},
{
"cell_type": "markdown",
"id": "3bb06b05",
"metadata": {},
"source": [
"Add a legend to the ratio plot"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "63519a5a",
"metadata": {
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"execution": {
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"outputs": [],
"source": [
"rp->GetUpperPad()->cd();\n",
"TLegend *legend = new TLegend(0.3, 0.7, 0.7, 0.85);\n",
"legend->AddEntry(\"h1\", \"First histogram\", \"l\");\n",
"legend->AddEntry(\"h2\", \"Second histogram\", \"le\");\n",
"legend->Draw();"
]
},
{
"cell_type": "markdown",
"id": "424c2d92",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "71392bf8",
"metadata": {
"collapsed": false,
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"source": [
"gROOT->GetListOfCanvases()->Draw()"
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