{
"cells": [
{
"cell_type": "markdown",
"id": "e6579dd4",
"metadata": {},
"source": [
"# gr012_polar\n",
"\n",
"Since TGraphPolar is a TGraphErrors, it is painted with\n",
"[TGraphPainter](https://root.cern/doc/master/classTGraphPainter.html) options.\n",
"\n",
"With GetPolargram we retrieve the polar axis to format it; see the\n",
"[TGraphPolargram documentation](https://root.cern/doc/master/classTGraphPolargram.html)\n",
"\n",
"\n",
"\n",
"**Author:** Olivier Couet, Jamie Gooding \n",
"This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Tuesday, May 19, 2026 at 08:37 PM."
]
},
{
"cell_type": "markdown",
"id": "ff52a56e",
"metadata": {},
"source": [
"Illustrates how to use TGraphPolar"
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "8e87e448",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:37:58.346263Z",
"iopub.status.busy": "2026-05-19T20:37:58.346127Z",
"iopub.status.idle": "2026-05-19T20:37:59.518429Z",
"shell.execute_reply": "2026-05-19T20:37:59.517862Z"
}
},
"outputs": [],
"source": [
"import math\n",
"\n",
"import numpy as np\n",
"import ROOT\n",
"\n",
"CPol = ROOT.TCanvas(\"CPol\", \"TGraphPolar Examples\", 1200, 600)\n",
"CPol.Divide(2, 1)"
]
},
{
"cell_type": "markdown",
"id": "ba9d62e9",
"metadata": {},
"source": [
"Left-side pad. Two graphs without errors"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "49fb35e4",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:37:59.528486Z",
"iopub.status.busy": "2026-05-19T20:37:59.528285Z",
"iopub.status.idle": "2026-05-19T20:37:59.650970Z",
"shell.execute_reply": "2026-05-19T20:37:59.649898Z"
}
},
"outputs": [],
"source": [
"CPol.cd(1)\n",
"xmin = 0\n",
"xmax = math.pi * 2\n",
"\n",
"x = np.array([])\n",
"y = np.array([])\n",
"xval1 = np.array([])\n",
"yval1 = np.array([])"
]
},
{
"cell_type": "markdown",
"id": "c2605e4e",
"metadata": {},
"source": [
"Graph 1 to be drawn with line and fill"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "2e1deb69",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:37:59.652649Z",
"iopub.status.busy": "2026-05-19T20:37:59.652510Z",
"iopub.status.idle": "2026-05-19T20:37:59.835887Z",
"shell.execute_reply": "2026-05-19T20:37:59.820368Z"
}
},
"outputs": [],
"source": [
"fplot = ROOT.TF1(\"fplot\", \"cos(2*x)*cos(20*x)\", xmin, xmax)\n",
"for ipt in range(1000):\n",
" x = np.append(x, ipt * (xmax - xmin) / 1000 + xmin)\n",
" y = np.append(y, fplot.Eval(x[ipt]))\n",
"\n",
"grP = ROOT.TGraphPolar(1000, x, y)\n",
"grP.SetLineColor(2)\n",
"grP.SetLineWidth(2)\n",
"grP.SetFillStyle(3012)\n",
"grP.SetFillColor(2)\n",
"grP.Draw(\"AFL\")"
]
},
{
"cell_type": "markdown",
"id": "abdbcc7a",
"metadata": {},
"source": [
"Graph 2 to be drawn superposed over graph 1, with curve and polymarker"
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "34bf39c8",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:37:59.849514Z",
"iopub.status.busy": "2026-05-19T20:37:59.849358Z",
"iopub.status.idle": "2026-05-19T20:37:59.962091Z",
"shell.execute_reply": "2026-05-19T20:37:59.961476Z"
}
},
"outputs": [],
"source": [
"for ipt in range(20):\n",
" xval1 = np.append(xval1, x[math.floor(1000 / 20 * ipt)])\n",
" yval1 = np.append(yval1, y[math.floor(1000 / 20 * ipt)])\n",
"\n",
"grP1 = ROOT.TGraphPolar(20, xval1, yval1)\n",
"grP1.SetMarkerStyle(29)\n",
"grP1.SetMarkerSize(2)\n",
"grP1.SetMarkerColor(4)\n",
"grP1.SetLineColor(4)\n",
"grP1.Draw(\"CP\")"
]
},
{
"cell_type": "markdown",
"id": "b7b85b95",
"metadata": {},
"source": [
"To format the polar axis, we retrieve the TGraphPolargram.\n",
"First update the canvas, otherwise GetPolargram returns 0"
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "49474dd1",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:37:59.975404Z",
"iopub.status.busy": "2026-05-19T20:37:59.975251Z",
"iopub.status.idle": "2026-05-19T20:38:00.185503Z",
"shell.execute_reply": "2026-05-19T20:38:00.185103Z"
}
},
"outputs": [
{
"data": {
"text/html": [
"\n",
"\n",
"\n",
"
\n",
"\n",
"\n",
"\n"
],
"text/plain": [
""
]
},
"metadata": {},
"output_type": "display_data"
}
],
"source": [
"CPol.Update()\n",
"if grP1.GetPolargram():\n",
" grP1.GetPolargram().SetTextColor(8)\n",
" grP1.GetPolargram().SetRangePolar(-math.pi, math.pi)\n",
" grP1.GetPolargram().SetNdivPolar(703)\n",
" grP1.GetPolargram().SetToRadian() # tell ROOT that the x and xval1 are in radians"
]
},
{
"cell_type": "markdown",
"id": "3dcf989f",
"metadata": {},
"source": [
"Right-side pad. One graph with errors"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "b71dc3f6",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:00.200567Z",
"iopub.status.busy": "2026-05-19T20:38:00.200416Z",
"iopub.status.idle": "2026-05-19T20:38:00.311731Z",
"shell.execute_reply": "2026-05-19T20:38:00.310316Z"
}
},
"outputs": [],
"source": [
"CPol.cd(2)\n",
"x2 = np.array([])\n",
"y2 = np.array([])\n",
"ex = np.array([])\n",
"ey = np.array([])\n",
"for ipt in range(30):\n",
" x2 = np.append(x2, x[math.floor(1000 / 30 * ipt)])\n",
" y2 = np.append(y2, 1.2 + 0.4 * math.sin(math.pi * 2 * ipt / 30))\n",
" ex = np.append(ex, 0.2 + 0.1 * math.cos(2 * math.pi / 30 * ipt))\n",
" ey = np.append(ey, 0.2)"
]
},
{
"cell_type": "markdown",
"id": "f538b7e7",
"metadata": {},
"source": [
"Grah to be drawn with polymarker and errors"
]
},
{
"cell_type": "code",
"execution_count": 7,
"id": "85e1cf11",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:00.313386Z",
"iopub.status.busy": "2026-05-19T20:38:00.313240Z",
"iopub.status.idle": "2026-05-19T20:38:00.417457Z",
"shell.execute_reply": "2026-05-19T20:38:00.416339Z"
}
},
"outputs": [],
"source": [
"grPE = ROOT.TGraphPolar(30, x2, y2, ex, ey)\n",
"grPE.SetMarkerStyle(22)\n",
"grPE.SetMarkerSize(1.5)\n",
"grPE.SetMarkerColor(5)\n",
"grPE.SetLineColor(6)\n",
"grPE.SetLineWidth(2)\n",
"grPE.Draw(\"EP\")"
]
},
{
"cell_type": "markdown",
"id": "1914a9dd",
"metadata": {},
"source": [
"To format the polar axis, we retrieve the TGraphPolargram.\n",
"First update the canvas, otherwise GetPolargram returns 0"
]
},
{
"cell_type": "code",
"execution_count": 8,
"id": "a7e775d5",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:00.419025Z",
"iopub.status.busy": "2026-05-19T20:38:00.418890Z",
"iopub.status.idle": "2026-05-19T20:38:00.536697Z",
"shell.execute_reply": "2026-05-19T20:38:00.536012Z"
}
},
"outputs": [],
"source": [
"CPol.Update()\n",
"if grPE.GetPolargram():\n",
" grPE.GetPolargram().SetTextSize(0.03)\n",
" grPE.GetPolargram().SetTwoPi()\n",
" grPE.GetPolargram().SetToRadian() # tell ROOT that the x2 values are in radians"
]
},
{
"cell_type": "markdown",
"id": "67012139",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 9,
"id": "11dccc27",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:00.538266Z",
"iopub.status.busy": "2026-05-19T20:38:00.538132Z",
"iopub.status.idle": "2026-05-19T20:38:00.725817Z",
"shell.execute_reply": "2026-05-19T20:38:00.711655Z"
}
},
"outputs": [
{
"data": {
"text/html": [
"\n",
"\n",
"\n",
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"\n",
"\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": {
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"file_extension": ".py",
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