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    "### Make the fake data for the Minuit class final example.\n",
    "\n",
    "For more on what's going in this code (\"What the heck is a 'data frame'?) see:  \n",
    "[Data Frame class reference](https://root.cern/doc/master/classROOT_1_1RDataFrame.html)  \n",
    "[Data Frame tutorials](https://root.cern.ch/doc/master/group__tutorial__dataframe.html)\n",
    "\n",
    "This is a ROOT C++ notebook, because it's easier to create lambda functions in C++ than it is in Python.\n",
    "\n",
    "**Warning:** If you're searching for physics in the following code, there isn't any. Really!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "#include \"ROOT/RDataFrame.hxx\"\n",
    "const int nevents = 100000;\n",
    "ROOT::RDataFrame dataframe(nevents);\n",
    "\n",
    "auto fileName = \"~seligman/root-class/datafile.root\";\n",
    "auto treeName = \"datatree\";\n",
    "\n",
    "TF1 elepton(\"elepton\",\"TMath::Landau(x,10,10)\",0,150);\n",
    "TF1 ehadron(\"ehadron\",\"TMath::Gaus(x,10,10)\",0,150);\n",
    "\n",
    "int event=0;\n",
    "// For each row in the ntuple (data frame), increment an\n",
    "// event number, fetch random numbers from the elepton and\n",
    "// ehadron functions, and write the row to a TTree 'treeName'\n",
    "// in file 'filename'. \n",
    "dataframe.Define(\"event\", [&event]() { ++event; return (double)event; })\n",
    "         .Define(\"elepton\", [&elepton]() { return elepton.GetRandom(); })\n",
    "         .Define(\"ehadron\", [&ehadron]() { return ehadron.GetRandom(); })\n",
    "         .Snapshot(treeName, fileName);"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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