{
"cells": [
{
"cell_type": "markdown",
"id": "67a9eda1",
"metadata": {},
"source": [
"# df010_trivialDataSource\n",
"Use the \"trivial data source\", an example data source implementation.\n",
"\n",
"This tutorial illustrates how use the RDataFrame in combination with a\n",
"RDataSource. In this case we use a RTrivialDS, which is nothing more\n",
"than a simple generator: it does not interface to any existing dataset.\n",
"The RTrivialDS has a single column, col0, which has value n for entry n.\n",
"\n",
"Note that RTrivialDS is only a demo data source implementation and superior alternatives\n",
"typically exist for production use (e.g. constructing an empty RDataFrame as `RDataFrame(nEntries)`).\n",
"\n",
"\n",
"\n",
"\n",
"**Author:** Danilo Piparo (CERN) \n",
"This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, May 19, 2026 at 08:09 PM."
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "0145bc04",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:09:38.005249Z",
"iopub.status.busy": "2026-05-19T20:09:38.005111Z",
"iopub.status.idle": "2026-05-19T20:09:38.964943Z",
"shell.execute_reply": "2026-05-19T20:09:38.963397Z"
}
},
"outputs": [],
"source": [
"import ROOT"
]
},
{
"cell_type": "markdown",
"id": "0822399b",
"metadata": {},
"source": [
"Create the data frame"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "74b54a69",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:09:38.987234Z",
"iopub.status.busy": "2026-05-19T20:09:38.987090Z",
"iopub.status.idle": "2026-05-19T20:09:39.376967Z",
"shell.execute_reply": "2026-05-19T20:09:39.376497Z"
}
},
"outputs": [],
"source": [
"MakeTrivialDataFrame = ROOT.RDF.MakeTrivialDataFrame\n",
"\n",
"nEvents = 128\n",
"\n",
"d_s = MakeTrivialDataFrame(nEvents)"
]
},
{
"cell_type": "markdown",
"id": "8566db7a",
"metadata": {},
"source": [
"Now we have a regular RDataFrame: the ingestion of data is delegated to\n",
"the RDataSource. At this point everything works as before."
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "9f14bfed",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:09:39.384188Z",
"iopub.status.busy": "2026-05-19T20:09:39.384060Z",
"iopub.status.idle": "2026-05-19T20:09:40.859776Z",
"shell.execute_reply": "2026-05-19T20:09:40.859317Z"
}
},
"outputs": [
{
"name": "stderr",
"output_type": "stream",
"text": [
"Info in : png file df010_trivialDataSource.png has been created\n"
]
},
{
"name": "stdout",
"output_type": "stream",
"text": [
"Saved figure to df010_trivialDataSource.png\n"
]
}
],
"source": [
"h_s = d_s.Define(\"x\", \"1./(1. + col0)\").Histo1D((\"h_s\", \"h_s\", 128, 0, .6), \"x\")\n",
"\n",
"c = ROOT.TCanvas()\n",
"c.SetLogy()\n",
"h_s.Draw()\n",
"c.SaveAs(\"df010_trivialDataSource.png\")\n",
"\n",
"print(\"Saved figure to df010_trivialDataSource.png\")"
]
},
{
"cell_type": "markdown",
"id": "4c94d5e2",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "6e567453",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:09:40.891269Z",
"iopub.status.busy": "2026-05-19T20:09:40.891115Z",
"iopub.status.idle": "2026-05-19T20:09:41.090681Z",
"shell.execute_reply": "2026-05-19T20:09:41.090229Z"
}
},
"outputs": [
{
"data": {
"text/html": [
"\n",
"\n",
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"\n",
"\n"
],
"text/plain": [
""
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"from ROOT import gROOT \n",
"gROOT.GetListOfCanvases().Draw()"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 3",
"language": "python",
"name": "python3"
},
"language_info": {
"codemirror_mode": {
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"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
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"nbformat": 4,
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