gr007_multigraph.py File Reference

Detailed Description

TMultiGraph is used to combine multiple graphs into one plot.

Allowing to overlay different graphs can be useful for comparing different datasets or for plotting multiple related graphs on the same canvas.

 
import numpy as np
import ROOT
 
ROOT.gStyle.SetOptFit()
c1 = ROOT.TCanvas("c1", "multigraph", 700, 500)
c1.SetGrid()
 
# Initialize a TMultiGraph to hold multiple graphs
# This ensures the entire dataset from all added graphs is visible without manual range adjustments.
mg = ROOT.TMultiGraph()
 
# Create first graph
n1 = 10
px1 = np.array([-0.1, 0.05, 0.25, 0.35, 0.5, 0.61, 0.7, 0.85, 0.89, 0.95])
py1 = np.array([-1, 2.9, 5.6, 7.4, 9, 9.6, 8.7, 6.3, 4.5, 1])
ex1 = np.array([0.05, 0.1, 0.07, 0.07, 0.04, 0.05, 0.06, 0.07, 0.08, 0.05])
ey1 = np.array([0.8, 0.7, 0.6, 0.5, 0.4, 0.4, 0.5, 0.6, 0.7, 0.8])
gr1 = ROOT.TGraphErrors(n1, px1, py1, ex1, ey1)
gr1.SetMarkerColor(ROOT.kBlue)
gr1.SetMarkerStyle(21)
 
gr1.Fit("gaus", "q")
func1 = gr1.GetListOfFunctions().FindObject("gaus")
func1.SetLineColor(ROOT.kBlue)
 
# Add the first graph to the multigraph
mg.Add(gr1)
 
# Create second graph
n2 = 10
x2 = np.array([-0.28, 0.005, 0.19, 0.29, 0.45, 0.56, 0.65, 0.80, 0.90, 1.01])
y2 = np.array([2.1, 3.86, 7, 9, 10, 10.55, 9.64, 7.26, 5.42, 2])
ex2 = np.array([0.04, 0.12, 0.08, 0.06, 0.05, 0.04, 0.07, 0.06, 0.08, 0.04])
ey2 = np.array([0.6, 0.8, 0.7, 0.4, 0.3, 0.3, 0.4, 0.5, 0.6, 0.7])
gr2 = ROOT.TGraphErrors(n2, x2, y2, ex2, ey2)
gr2.SetMarkerColor(ROOT.kRed)
gr2.SetMarkerStyle(20)
 
gr2.Fit("pol5", "q")
func2 = gr2.GetListOfFunctions().FindObject("pol5")
func2.SetLineColor(ROOT.kRed)
func2.SetLineStyle(2)
 
# Add the second graph to the multigraph
mg.Add(gr2)
 
mg.Draw("ap")
 
# Force drawing of canvas to generate the fit TPaveStats
c1.Update()
 
stats1 = gr1.GetListOfFunctions().FindObject("stats")
stats2 = gr2.GetListOfFunctions().FindObject("stats")
 
if stats1 and stats2:
    stats1.SetTextColor(ROOT.kBlue)
    stats2.SetTextColor(ROOT.kRed)
    stats1.SetX1NDC(0.12)
    stats1.SetX2NDC(0.32)
    stats1.SetY1NDC(0.82)
    stats2.SetX1NDC(0.72)
    stats2.SetX2NDC(0.92)
    stats2.SetY1NDC(0.75)
    c1.Modified()

Author

Rene Brun, Jamie Gooding

Definition in file gr007_multigraph.py.