gr006_scatter.py

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## \file
## \ingroup tutorial_graphs
## \notebook
## \preview Draw a scatter plot for 4 variables, mapped to: x, y, marker colour and marker size.
##
## TScatter is available since ROOT v.6.30. See the [TScatter documentation](https://root.cern/doc/master/classTScatter.html)
##
## \macro_image
## \macro_code
## \author Olivier Couet, Jamie Gooding
 
import numpy as np
import ROOT
 
canvas = ROOT.TCanvas()
canvas.SetRightMargin(0.14)
ROOT.gStyle.SetPalette(ROOT.kBird, 0, 0.6)  # define a transparent palette
 
n = 175
 
x = np.array([])
y = np.array([])
c = np.array([])
s = np.array([])
 
# Define four random data sets
r = ROOT.TRandom()
for i in range(n):
    x = np.append(x, 100 * r.Rndm(i))
    y = np.append(y, 200 * r.Rndm(i))
    c = np.append(c, 300 * r.Rndm(i))
    s = np.append(s, 400 * r.Rndm(i))
 
scatter = ROOT.TScatter(n, x, y, c, s)
scatter.SetMarkerStyle(20)
scatter.SetTitle("Scatter plot titleX titleY titleZ title")
scatter.GetXaxis().SetRangeUser(20.0, 90.0)
scatter.GetYaxis().SetRangeUser(55.0, 90.0)
scatter.GetZaxis().SetRangeUser(10.0, 200.0)
# an alternative way to zoom the Z-axis:
# scatter->GetHistogram()->SetMinimum(10);
# scatter->GetHistogram()->SetMaximum(200);
scatter.Draw("A")