def plotStackedHistosWithData(histosPerGroup={}, outputDir='', canvasname='', canvastitle='', colors={}, verbose=False):
    "histosPerGroup[group], where group=data is treated as special"
    groups = histosPerGroup.keys()
    mkdirIfNeeded(outputDir)
    missingGroups = [g for g, h in histosPerGroup.iteritems() if not h]
    if missingGroups:
        if verbose : print "skip %s, missing histos for %s"%(histoname, str(missingGroups))
        return
    bkgHistos = dict([(g, h) for g, h in histosPerGroup.iteritems() if not isDataSample(g)])
    totBkg = summedHisto(bkgHistos.values())
    err_band = buildErrBandGraph(totBkg, computeStatErr2(totBkg))
    emptyBkg = totBkg.Integral()==0
    histoname, region = totBkg.GetName(), 'emu' # tmp replacement vars, to be fixed
    if emptyBkg:
        if verbose : print "empty backgrounds, skip %s"%histoname
        return
    can = r.TCanvas(canvasname, canvastitle, 800, 600)
    can.cd()
    pm = totBkg # pad master
    pm.SetStats(False)
    pm.Draw('axis')
    can.Update() # necessary to fool root's dumb object ownership
    stack = r.THStack('stack_'+histoname,'')
    can.Update()
    r.SetOwnership(stack, False)
    for s, h in bkgHistos.iteritems() :
        h.SetFillColor(colors[s] if s in colors else r.kOrange)
        h.SetDrawOption('bar')
        h.SetDirectory(0)
        stack.Add(h)
    stack.Draw('hist same')
    err_band.Draw('E2 same')
    data = histosPerGroup['data'] if 'data' in histosPerGroup else None
    if data and data.GetEntries():
        data.SetMarkerStyle(r.kFullDotLarge)
        data.Draw('p same')
        if verbose :
            print "integrals : {0} tot.bkg.: {1}, data: {2}".format(histoname, totBkg.Integral(), data.Integral())
    else:
        print "no data"
    yMin, yMax = getMinMax([h for h in [totBkg, data, err_band] if h])
    pm.SetMinimum(0.0)
    pm.SetMaximum(1.1*yMax)
    can.Update()
    topRightLabel(can, "#splitline{%s}{%s}"%(histoname, region), xpos=0.15, ypos=(1.0-0.5*can.GetTopMargin()), align=13)
    drawLegendWithDictKeys(can, dictSum(bkgHistos, {'stat err':err_band}), opt='f')
    can.RedrawAxis()
    can._stack = stack
    can._histos = [h for h in stack.GetHists()]+[data]
    can.Update()
    filename=os.path.join(outputDir, histoname+'.png')
    rmIfExists(filename)
    can.SaveAs(filename)
def plotStackedHistos(histosPerGroup={}, outputDir='', region='', colors={}, verbose=False):
    groups = histosPerGroup.keys()
    variables = first(histosPerGroup).keys()
    mkdirIfNeeded(outputDir)
    histosPerName = dict([(var+'_'+tol, # one canvas for each histo, so key with histoname w/out group
                           dict([(g, histosPerGroup[g][var][tol]) for g in groups]))
                          for var in variables for tol in ['tight','loose']])
    for histoname, histosPerGroup in histosPerName.iteritems():
        missingGroups = [g for g, h in histosPerGroup.iteritems() if not h]
        if missingGroups:
            if verbose : print "skip %s, missing histos for %s"%(histoname, str(missingGroups))
            continue
        bkgHistos = dict([(g, h) for g, h in histosPerGroup.iteritems() if isBkgSample(g)])
        totBkg = summedHisto(bkgHistos.values())
        err_band = buildErrBandGraph(totBkg, computeStatErr2(totBkg))
        emptyBkg = totBkg.Integral()==0
        if emptyBkg:
            if verbose : print "empty backgrounds, skip %s"%histoname
            continue
        can = r.TCanvas('c_'+histoname, histoname, 800, 600)
        can.cd()
        pm = totBkg # pad master
        pm.SetStats(False)
        pm.Draw('axis')
        can.Update() # necessary to fool root's dumb object ownership
        stack = r.THStack('stack_'+histoname,'')
        can.Update()
        r.SetOwnership(stack, False)
        for s, h in bkgHistos.iteritems() :
            h.SetFillColor(colors[s] if s in colors else r.kOrange)
            h.SetDrawOption('bar')
            h.SetDirectory(0)
            stack.Add(h)
        stack.Draw('hist same')
        err_band.Draw('E2 same')
        data = histosPerGroup['data'] if 'data' in histosPerGroup else None
        if data and data.GetEntries():
            data.SetMarkerStyle(r.kFullDotLarge)
            data.Draw('p same')
        yMin, yMax = getMinMax([h for h in [totBkg, data, err_band] if h])
        pm.SetMinimum(0.0)
        pm.SetMaximum(1.1*yMax)
        can.Update()
        topRightLabel(can, "#splitline{%s}{%s}"%(histoname, region), xpos=0.125, align=13)
        drawLegendWithDictKeys(can, dictSum(bkgHistos, {'stat err':err_band}), opt='f')
        can.RedrawAxis()
        can._stack = stack
        can._histos = [h for h in stack.GetHists()]+[data]
        can.Update()
        can.SaveAs(os.path.join(outputDir, histoname+'.png'))