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hsum.py File Reference

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 hsum
 

Detailed Description

View in nbviewer Open in SWAN Simple example illustrating how to use the C++ interpreter

from ROOT import TCanvas, TH1F, TSlider
from ROOT import gROOT, gBenchmark, gRandom
# Create a new canvas, and customize it.
c1 = TCanvas( 'c1', 'The HSUM example', 200, 10, 600, 400 )
c1.SetGrid();
gBenchmark.Start( 'hsum' )
# Create some histograms.
total = TH1F( 'total', 'This is the total distribution', 100, -4, 4 )
main = TH1F( 'main', 'Main contributor', 100, -4, 4 )
s1 = TH1F( 's1', 'This is the first signal', 100, -4, 4 )
s2 = TH1F( 's2', 'This is the second signal', 100, -4, 4 )
total.Sumw2() # this makes sure that the sum of squares of weights will be stored
# Set canvas/frame attributes.
total.SetMarkerStyle( 21 )
total.SetMarkerSize( 0.7 )
main.SetFillColor( 16 )
s1.SetFillColor( 42 )
s2.SetFillColor( 46 )
# Initialize random number generator.
gRandom.SetSeed()
gauss, landau = gRandom.Gaus, gRandom.Landau
# for speed, bind and cache the Fill member functions
histos = [ 'total', 'main', 's1', 's2' ]
for name in histos:
exec('%sFill = %s.Fill' % (name,name))
# Fill histograms randomly
kUPDATE = 500
for i in range( 10000 ):
# Generate random values.
xmain = gauss( -1, 1.5 )
xs1 = gauss( -0.5, 0.5 )
xs2 = landau( 1, 0.15 )
mainFill( xmain )
# Fill histograms.
s1Fill( xs1, 0.3 )
s2Fill( xs2, 0.2 )
totalFill( xmain )
totalFill( xs1, 0.3 )
totalFill( xs2, 0.2 )
# Update display every kUPDATE events.
if i and (i%kUPDATE) == 0 :
if i == kUPDATE :
total.Draw( 'e1p' )
main.Draw( 'same' )
s1.Draw( 'same' )
s2.Draw( 'same' )
c1.Update()
slider = TSlider( 'slider', 'test', 4.2, 0, 4.6, total.GetMaximum(), 38 )
slider.SetFillColor( 46 )
if slider:
slider.SetRange( 0, float(i) / 10000. )
c1.Modified()
c1.Update()
# Destroy member functions cache.
for name in histos:
exec('del %sFill' % name)
del histos
# Done, finalized and trigger an update.
slider.SetRange( 0, 1 )
total.Draw( 'sameaxis' ) # to redraw axis hidden by the fill area
c1.Modified()
c1.Update()
gBenchmark.Show( 'hsum' )
Author
Wim Lavrijsen

Definition in file hsum.py.

TGeant4Unit::gauss
static constexpr double gauss
Definition: TGeant4SystemOfUnits.h:269
TCanvas
Definition: TCanvas.h:23
TH1F
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:572
TSlider
Definition: TSlider.h:18