gr014_polar3.py

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## \file
## \ingroup tutorial_graphs
## \notebook
## \preview Create a polar graph using a TF1 and draw it with PI axis.
## See the [TGraphPolar documentation](https://root.cern/doc/master/classTGraphPolar.html)
##
## Since TGraphPolar is a TGraphErrors, it is painted with
## [TGraphPainter](https://root.cern/doc/master/classTGraphPainter.html) options.
##
## \macro_image
## \macro_code
## \author Olivier Couet, Jamie Gooding
 
import math
 
import numpy as np
import ROOT
 
CPol = ROOT.TCanvas("CPol", "TGraphPolar Examples", 500, 500)
 
rmin = 0
rmax = math.pi * 2
r = np.array([])
theta = np.array([])
 
fp1 = ROOT.TF1("fplot", "cos(x)", rmin, rmax)
for ipt in range(1000):
    r = np.append(r, ipt * (rmax - rmin) / 1000 + rmin)
    theta = np.append(theta, fp1.Eval(r[ipt]))
 
grP1 = ROOT.TGraphPolar(1000, r, theta)
grP1.SetTitle("")
grP1.SetLineColor(2)
grP1.Draw("AOL")