{
"cells": [
{
"cell_type": "markdown",
"id": "22d5e6df",
"metadata": {},
"source": [
"# gr013_polar2\n",
"See the [TGraphPolar documentation](https:#root.cern/doc/master/classTGraphPolar.html)\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": "code",
"execution_count": 1,
"id": "9dcbd129",
"metadata": {
"collapsed": false,
"execution": {
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"iopub.status.idle": "2026-05-19T20:38:01.804126Z",
"shell.execute_reply": "2026-05-19T20:38:01.803677Z"
}
},
"outputs": [],
"source": [
"import numpy as np\n",
"import ROOT\n",
"\n",
"CPol = ROOT.TCanvas(\"CPol\", \"TGraphPolar Example\", 500, 500)\n",
"\n",
"theta = np.array([])\n",
"radius = np.array([])\n",
"etheta = np.array([])\n",
"eradius = np.array([])\n",
"\n",
"for i in range(8):\n",
" theta = np.append(theta, (i + 1) * (np.pi / 4.0))\n",
" radius = np.append(radius, (i + 1) * 0.05)\n",
" etheta = np.append(etheta, np.pi / 8.0)\n",
" eradius = np.append(eradius, 0.05)\n",
"\n",
"grP1 = ROOT.TGraphPolar(8, theta, radius, etheta, eradius)\n",
"grP1.SetTitle(\"\")\n",
"\n",
"grP1.SetMarkerStyle(20)\n",
"grP1.SetMarkerSize(2.0)\n",
"grP1.SetMarkerColor(4)\n",
"grP1.SetLineColor(2)\n",
"grP1.SetLineWidth(3)"
]
},
{
"cell_type": "markdown",
"id": "e2d530e2",
"metadata": {},
"source": [
"Draw with polymarker and errors"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "4f44d1be",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:01.827487Z",
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"shell.execute_reply": "2026-05-19T20:38:01.948416Z"
}
},
"outputs": [],
"source": [
"grP1.Draw(\"PE\")"
]
},
{
"cell_type": "markdown",
"id": "0e34fbed",
"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": 3,
"id": "15e91642",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:01.955170Z",
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"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().SetToRadian() # tell ROOT that the theta values are in radians"
]
},
{
"cell_type": "markdown",
"id": "04992070",
"metadata": {},
"source": [
"Draw all canvases "
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "e9e37c06",
"metadata": {
"collapsed": false,
"execution": {
"iopub.execute_input": "2026-05-19T20:38:02.144148Z",
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"shell.execute_reply": "2026-05-19T20:38:02.256687Z"
}
},
"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"
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