{
"cells": [
{
"cell_type": "markdown",
"id": "085946d3",
"metadata": {},
"source": [
"# hist004_TH1_labels\n",
"\n",
"A TH1 can have named bins that are filled with the method overload TH1::Fill(const char*, double)\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 08:11 PM."
]
},
{
"cell_type": "markdown",
"id": "a5af0ad3",
"metadata": {},
"source": [
"Create the histogram"
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "9c6e4003",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:52.666440Z",
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"shell.execute_reply": "2026-05-19T20:11:52.995457Z"
}
},
"outputs": [],
"source": [
"const std::array people{\"Jean\", \"Pierre\", \"Marie\", \"Odile\", \"Sebastien\", \"Fons\", \"Rene\",\n",
" \"Nicolas\", \"Xavier\", \"Greg\", \"Bjarne\", \"Anton\", \"Otto\", \"Eddy\",\n",
" \"Peter\", \"Pasha\", \"Philippe\", \"Suzanne\", \"Jeff\", \"Valery\"};"
]
},
{
"cell_type": "markdown",
"id": "8a7b83b1",
"metadata": {},
"source": [
"Start with an arbitrary amount of bins and an arbitrary range, but this will be extended thanks to SetCanExtend()."
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "b6221643",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:53.003368Z",
"iopub.status.busy": "2026-05-19T20:11:53.003224Z",
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"shell.execute_reply": "2026-05-19T20:11:53.206449Z"
}
},
"outputs": [],
"source": [
"int nBins = 3;\n",
"double rangeMin = 0.0;\n",
"double rangeMax = 3.0;\n",
"auto *h = new TH1D(\"h\", \"test\", nBins, rangeMin, rangeMax);"
]
},
{
"cell_type": "markdown",
"id": "358eb8a2",
"metadata": {},
"source": [
"Disable the default stats box when drawing this histogram"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "8a280043",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:53.209032Z",
"iopub.status.busy": "2026-05-19T20:11:53.208919Z",
"iopub.status.idle": "2026-05-19T20:11:53.412655Z",
"shell.execute_reply": "2026-05-19T20:11:53.411953Z"
}
},
"outputs": [],
"source": [
"h->SetStats(0);\n",
"h->SetFillColor(38);"
]
},
{
"cell_type": "markdown",
"id": "7c7e328c",
"metadata": {},
"source": [
"Allow both axes to extend past the initial range we gave in the constructor"
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "b2808efd",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:53.414366Z",
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"iopub.status.idle": "2026-05-19T20:11:53.618001Z",
"shell.execute_reply": "2026-05-19T20:11:53.617322Z"
}
},
"outputs": [],
"source": [
"h->SetCanExtend(TH1::kAllAxes);"
]
},
{
"cell_type": "markdown",
"id": "6c5dc270",
"metadata": {},
"source": [
"Fill the Y axis with arbitrary values, a random amount per bin"
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "9ea22f3b",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:53.619544Z",
"iopub.status.busy": "2026-05-19T20:11:53.619430Z",
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"shell.execute_reply": "2026-05-19T20:11:53.820900Z"
}
},
"outputs": [],
"source": [
"TRandom3 rng;\n",
"for (int i = 0; i < 5000; i++) {\n",
" int r = rng.Rndm() * 20;\n",
" // `Fill()` called with a const char* as the first argument will add a value to the bin with that name,\n",
" // creating it if it doesn't exist yet.\n",
" h->Fill(people[r], 1);\n",
"}"
]
},
{
"cell_type": "markdown",
"id": "5478fa14",
"metadata": {},
"source": [
"Remove empty bins"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "5da29eb1",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:53.834378Z",
"iopub.status.busy": "2026-05-19T20:11:53.834254Z",
"iopub.status.idle": "2026-05-19T20:11:54.037911Z",
"shell.execute_reply": "2026-05-19T20:11:54.037488Z"
}
},
"outputs": [],
"source": [
"h->LabelsDeflate();\n",
"\n",
"auto *c1 = new TCanvas(\"c1\", \"demo bin labels\", 10, 10, 900, 500);"
]
},
{
"cell_type": "markdown",
"id": "04878a4e",
"metadata": {},
"source": [
"Enable the grid in the plot"
]
},
{
"cell_type": "code",
"execution_count": 7,
"id": "c66aabaa",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:54.049273Z",
"iopub.status.busy": "2026-05-19T20:11:54.049141Z",
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"shell.execute_reply": "2026-05-19T20:11:54.267555Z"
}
},
"outputs": [],
"source": [
"c1->SetGrid();\n",
"c1->SetTopMargin(0.15);"
]
},
{
"cell_type": "markdown",
"id": "be5aad62",
"metadata": {},
"source": [
"Draw the histogram"
]
},
{
"cell_type": "code",
"execution_count": 8,
"id": "38961e35",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:54.270219Z",
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"shell.execute_reply": "2026-05-19T20:11:54.473554Z"
}
},
"outputs": [],
"source": [
"h->Draw();"
]
},
{
"cell_type": "markdown",
"id": "a873f75c",
"metadata": {},
"source": [
"Draw a boxed text\n",
"\"brNDC\" = coordinates draw bottom-right shadow and pass the coordinates in normalized device coordinates"
]
},
{
"cell_type": "code",
"execution_count": 9,
"id": "456c7270",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:11:54.476056Z",
"iopub.status.busy": "2026-05-19T20:11:54.475937Z",
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"shell.execute_reply": "2026-05-19T20:11:54.679229Z"
}
},
"outputs": [],
"source": [
"auto *pt = new TPaveText(0.7, 0.85, 0.98, 0.98, \"brNDC\");\n",
"pt->SetFillColor(18);\n",
"pt->SetTextAlign(12);\n",
"pt->AddText(\"Use the axis Context Menu LabelsOption\");\n",
"pt->AddText(\" \\\"a\\\" to sort by alphabetic order\");\n",
"pt->AddText(\" \\\">\\\" to sort by decreasing values\");\n",
"pt->AddText(\" \\\"<\\\" to sort by increasing values\");\n",
"pt->Draw();"
]
},
{
"cell_type": "markdown",
"id": "88df9cd5",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 10,
"id": "a6eb23bc",
"metadata": {
"collapsed": false,
"execution": {
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"shell.execute_reply": "2026-05-19T20:11:54.899670Z"
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},
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"source": [
"gROOT->GetListOfCanvases()->Draw()"
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