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rf903_numintcache.py File Reference

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 rf903_numintcache
 

Detailed Description

View in nbviewer Open in SWAN Numeric algorithm tuning: caching of slow numeric integrals and parameterizations of slow numeric integrals

import sys
import ROOT
def getWorkspace(mode):
# Create, save or load workspace with pdf
# -----------------------------------------------------------------------------------
#
# Mode = 0 : Create workspace for plain running (no integral caching)
# Mode = 1 : Generate workspace with precalculated integral and store it on file
# Mode = 2 : Load previously stored workspace from file
w = ROOT.RooWorkspace()
if mode != 2:
# Create empty workspace workspace
w = ROOT.RooWorkspace("w", 1)
# Make a difficult to normalize pdf in 3 dimensions that is
# integrated numerically.
w.factory(
"EXPR::model('1/((x-a)*(x-a)+0.01)+1/((y-a)*(y-a)+0.01)+1/((z-a)*(z-a)+0.01)',x[-1,1],y[-1,1],z[-1,1],a[-5,5])")
if mode == 1:
# Instruct model to precalculate normalization integral that integrate at least
# two dimensions numerically. In self specific case the integral value for
# all values of parameter 'a' are stored in a histogram and available for use
# in subsequent fitting and plotting operations (interpolation is
# applied)
# w.pdf("model").setNormValueCaching(3)
w.pdf("model").setStringAttribute("CACHEPARMINT", "x:y:z")
# Evaluate pdf once to trigger filling of cache
normSet = ROOT.RooArgSet(w.var("x"), w.var("y"), w.var("z"))
w.pdf("model").getVal(normSet)
w.writeToFile("rf903_numintcache.root")
if (mode == 2):
# Load preexisting workspace from file in mode==2
f = ROOT.TFile("rf903_numintcache.root")
w = f.Get("w")
# Return created or loaded workspace
return w
mode = 0
# Mode = 0 : Run plain fit (slow)
# Mode = 1 : Generate workspace with precalculated integral and store it on file (prepare for accelerated running)
# Mode = 2 : Run fit from previously stored workspace including cached
# integrals (fast, run in mode=1 first)
# Create, save or load workspace with pdf
# -----------------------------------------------------------------------------------
# Make/load workspace, here in mode 1
w = getWorkspace(mode)
if mode == 1:
# Show workspace that was created
w.Print()
# Show plot of cached integral values
hhcache = w.expensiveObjectCache().getObj(1)
if (hhcache):
ROOT.TCanvas("rf903_numintcache", "rf903_numintcache", 600, 600)
hhcache.createHistogram("a").Draw()
else:
ROOT.RooFit.Error("rf903_numintcache",
"Cached histogram is not existing in workspace")
sys.exit()
# Use pdf from workspace for generation and fitting
# -----------------------------------------------------------------------------------
# ROOT.This is always slow (need to find maximum function value
# empirically in 3D space)
d = w.pdf("model").generate(
ROOT.RooArgSet(
w.var("x"),
w.var("y"),
w.var("z")),
1000)
# ROOT.This is slow in mode 0, fast in mode 1
w.pdf("model").fitTo(
d, ROOT.RooFit.Verbose(
ROOT.kTRUE), ROOT.RooFit.Timer(
ROOT.kTRUE))
# Projection on x (always slow as 2D integral over Y, at fitted value of a
# is not cached)
framex = w.var("x").frame(ROOT.RooFit.Title("Projection of 3D model on X"))
d.plotOn(framex)
w.pdf("model").plotOn(framex)
# Draw x projection on canvas
c = ROOT.TCanvas("rf903_numintcache", "rf903_numintcache", 600, 600)
framex.Draw()
c.SaveAs("rf903_numintcache.png")
# Make workspace available on command line after macro finishes
ROOT.gDirectory.Add(w)
Date
February 2018
Authors
Clemens Lange, Wouter Verkerke (C++ version)

Definition in file rf903_numintcache.py.

Draw
th1 Draw()