plotROC.py

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#!/bin/env python
##
## This script reads the output.root file produced by confusionMatrixTree.py
## and plots the ROC curve (signal efficiency vs bkgd efficiency).  Optionally 
## one can specificy several output.root files and produce an overlay of ROC
## the ROC curves from each.  Specify as an argument a config file (example
## is rocExample.cfg) that details the input root files, which variables to
## sum together to make the classifier, what is signal, what is background,
##
import sys
from array import array
import argparse
from ConfigParser import SafeConfigParser
#from collections import OrderedDict

nBins=500
binLo=0.0
binHi=1.0

fontSize=0.05

def getEfficiencies(t,classifierExpression,cut):
 
    fullExpression="%s>>h" %classifierExpression
    h=TH1F("h","h",nBins,binLo,binHi)
    t.Draw(fullExpression,cut)

    totIntegral=h.Integral()

    return array('f',  [h.Integral(iBin,nBins)/totIntegral for iBin in range(1,nBins)] )


prog=sys.argv[0]
parser = argparse.ArgumentParser(prog=prog, description='Make dataset definitions page')


parser.add_argument("cfgFile",help="Configuration file",type=str)
args=parser.parse_args()

mainDefaults={}
mainDefaults["classifierExpression"]="nueqe+nuedis+nueres+nueother"
mainDefaults["title"]="#nu_{e} Classifier"
mainDefaults["trueSignalCut"]="truelabel >=4 && truelabel <=7"

mainDefaults["legendX"]=0.5
mainDefaults["legendY"]=0.5
mainDefaults["legendW"]=0.4
mainDefaults["legendH"]=0.4

mainDefaults[    "signalEffRange"]="0.0 1.0"
mainDefaults["backgroundEffRange"]="0.0 1.0"

cfg=SafeConfigParser(mainDefaults)
cfg.readfp(open(args.cfgFile))


classifierExpression=cfg.get("main","classifierExpression")
title=cfg.get("main","title")
trueSignalCut=cfg.get("main","trueSignalCut")

instancesNames=cfg.get("main","instances").split()

outFile=cfg.get("main","outFile")

legendX=float(cfg.get("main","legendX"))
legendY=float(cfg.get("main","legendY"))
legendW=float(cfg.get("main","legendW"))
legendH=float(cfg.get("main","legendH"))

(sgnlMin,sgnlMax)=tuple([float(x) for x in cfg.get("main","signalEffRange").split()])
(bkgdMin,bkgdMax)=tuple([float(x) for x in cfg.get("main","backgroundEffRange").split()])

from ROOT import *
gROOT.SetBatch(1)

rocCurves=[]
for instanceName in instancesNames:
    fileName=cfg.get(instanceName,"fileName")
    iFile=TFile(fileName,"read")
    iTree=iFile.Get("t")

    sgnlEfficiencies=getEfficiencies(iTree,classifierExpression,trueSignalCut)

    trueBackgroundCut= "! (%s)" %trueSignalCut
    bkgdEfficiencies=getEfficiencies(iTree,classifierExpression,trueBackgroundCut)

    rocTitle=cfg.get(instanceName,"title")
    nPoints=len(bkgdEfficiencies)
    rocCurve=TGraph(nPoints,bkgdEfficiencies,sgnlEfficiencies)
    rocCurve.SetTitle(title)
    rocCurves.append((rocCurve,rocTitle))

rocCan=TCanvas("rocCan","rocCan")
rocCan.SetLeftMargin(0.1)
rocCan.SetBottomMargin(0.12)

leg=TLegend(legendX, legendY-legendH, legendX+legendW, legendY)
leg.SetBorderSize(0)

for i, (rocCurve,rocTitle) in enumerate(rocCurves):
    rocCurve.SetFillColor(0)
    rocCurve.SetLineColor(i+1)
    rocCurve.SetLineWidth(3)
    leg.AddEntry(rocCurve, rocTitle)
    if i==0:
        rocCurve.Draw("AL")
        rocCurve.GetXaxis().SetTitle("Background Efficiency")
        rocCurve.GetXaxis().SetRangeUser(bkgdMin, bkgdMax)
        rocCurve.GetXaxis().SetLabelSize(fontSize)
        rocCurve.GetXaxis().SetTitleSize(fontSize)

        rocCurve.GetYaxis().SetTitle("Signal Efficiency")
        rocCurve.GetYaxis().SetRangeUser(sgnlMin,sgnlMax)
        rocCurve.GetYaxis().SetLabelSize(fontSize)
        rocCurve.GetYaxis().SetTitleSize(fontSize)

        rocCan.Update()
    else:
        rocCurve.Draw("L")

leg.Draw()
rocCan.Print(outFile)