Returning Issue with TH1F from function

ROOT
1

Dear experts,

I am trying to return TH1F from a function but it was returning me type “PyROOT_NoneType”. For this I searched and fixed this issue using link [1] & [2].

But, later when I am going to save the histogram using

c1.SaveAs("test.pdf")

Then it is giving me error:

     c1.SaveAs("test.pdf");
SystemError: void TPad::SaveAs(const char* filename = "", const char* option = "") =>
     problem in C++; program state has been reset

Please let me know how I can fix this. you can see part of my code [3]

with regards,
Ram

===============

[1] Returning TH1F from function
[2] NoneType Feturned from Function that returns TH1F

[3] code:

def aQGC_GetHisto(plot_info, key1, ColNum):

    file1 = ROOT.TFile(plot_info["file_name"][0])
    tree1 = file1.Get(plot_info["tree_folder"] + plot_info["tree_name"])

    hist = ROOT.TH1F()
    hist1 = ROOT.TH1F("hist1", "Test", plot_info["nbin"], plot_info["xmin"], plot_info["xmax"])    
    tree1.Draw(plot_info["tree_var"][0] + ">>hist1","LHEWeights["+str(key1)+"]","",1000)
    return hist1
        
def aQGC_plotting (plot_info, aQGC_key, aQGC_val, outputNameString):
    c1 = getCanvas()   
    legend = ROOT.TLegend(.8 ,.60 ,1.0 ,.900)
    legend.SetFillColor(ROOT.kWhite)

    hist = ROOT.TH1F()
    print type(hist)
    for i in range(0,1):
        hist = aQGC_GetHisto(plot_info,aQGC_key[i],i)
        print "hist type : ",type(hist)
        legend.AddEntry(hist, aQGC_val[i].replace("_m"," = ").replace("p",".").replace("_0"," = 0"))
        if i==0:
                hist.Draw()
        else:
                hist.Draw("sames")
    legend.Draw("same")
    #setTDRStyle(c1, 1, 13, plot_info["printCMS"]) 
    hist1.GetXaxis().SetTitle(plot_info["xlabel"])
    if plot_info["ylabel"] == "":
        plot_info["ylabel"] = "Events / %s GeV" % int(hist1.GetBinWidth(1))
    hist1.GetYaxis().SetTitle(plot_info["ylabel"])
    c1.SaveAs("test.pdf")
2

Hi,

what script are you actually running?

Cheers,
D

3

Hi,

I just added part of my code in question.

4

Hi,

is the c1 you get from getCanvas() still well defined when you try to print, e.g. is it non-null?

Cheers,
D

5

Hi,

Thanks for help.

when I print c1 then I got

<ROOT.TCanvas object ("c2") at 0x487a950>

Here [1] is my function getCanvas() is defined.

[1]

def getCanvas():
    H_ref = 600; 
    W_ref = 800; 
    W = W_ref
    H  = H_ref

    T = 0.08*H_ref
    B = 0.12*H_ref 
    L = 0.12*W_ref
    R = 0.04*W_ref

    canvas = ROOT.TCanvas("c2","c2",50,50,W,H)
    canvas.SetFillColor(0)
    canvas.SetBorderMode(0)
    canvas.SetFrameFillStyle(0)
    canvas.SetFrameBorderMode(0)
    canvas.SetLeftMargin( L/W )
    canvas.SetRightMargin( R/W )
    canvas.SetTopMargin( T/H )
    canvas.SetBottomMargin( B/H )
    canvas.SetTickx(0)
    canvas.SetTicky(0) 
    return canvas
6

Hi,

For you information, my older version of this code is working, where I did not defined a function aQGC_GetHisto. I am just defining all my histograms in the same function aQGC_plotting and saving there only.

def aQGC_plotting (plot_info, aQGC_key, aQGC_val, outputNameString):
    c1 = getCanvas()
    legend = ROOT.TLegend(.8 ,.60 ,1.0 ,.900)
    legend.SetFillColor(ROOT.kWhite)
    file1 = ROOT.TFile(plot_info["file_name"][0])
    tree1 = file1.Get(plot_info["tree_folder"] + plot_info["tree_name"])

    hist1 = ROOT.TH1F("hist1", "Test", plot_info["nbin"], plot_info["xmin"], plot_info["xmax"])    
    hist2 = ROOT.TH1F("hist2", "Test", plot_info["nbin"], plot_info["xmin"], plot_info["xmax"])    
    hist3 = ROOT.TH1F("hist3", "Test", plot_info["nbin"], plot_info["xmin"], plot_info["xmax"])    
    hist4 = ROOT.TH1F("hist4", "Test", plot_info["nbin"], plot_info["xmin"], plot_info["xmax"])    
    hist5 = ROOT.TH1F("hist5", "Test", plot_info["nbin"], plot_info["xmin"], plot_info["xmax"])    

    if len(aQGC_key) > 0:
        tree1.Draw(plot_info["tree_var"][0] + ">>hist1","LHEWeights["+str(aQGC_key[0])+"]")
        legend.AddEntry(hist1, aQGC_val[0].replace("_m"," = ").replace("p",".").replace("_0"," = 0"))
        hist1.Scale(1/hist1.Integral())
        setHistAttributes(hist1, plot_info, ROOT.kBlack,0)
    if len(aQGC_key) >= 2:
        tree1.Draw(plot_info["tree_var"][0] + ">>hist2","LHEWeights["+str(aQGC_key[1])+"]")
        legend.AddEntry(hist2, aQGC_val[1].replace("_m"," = ").replace("p",".").replace("_0"," = 0"))
        hist2.Scale(1/hist2.Integral())
        setHistAttributes(hist2, plot_info, ROOT.kRed,0)
    if len(aQGC_key) >= 3:
        tree1.Draw(plot_info["tree_var"][0] + ">>hist3","LHEWeights["+str(aQGC_key[2])+"]")
        legend.AddEntry(hist3, aQGC_val[2].replace("_m"," = ").replace("p",".").replace("_0"," = 0"))
        hist3.Scale(1/hist3.Integral())
        setHistAttributes(hist3, plot_info, ROOT.kGreen,0)
    if len(aQGC_key) >= 4:
        tree1.Draw(plot_info["tree_var"][0] + ">>hist4","LHEWeights["+str(aQGC_key[3])+"]")
        legend.AddEntry(hist4, aQGC_val[3].replace("_m"," = ").replace("p",".").replace("_0"," = 0"))
        hist4.Scale(1/hist4.Integral())
        setHistAttributes(hist4, plot_info, ROOT.kYellow,0)
    if len(aQGC_key) >= 5:
        tree1.Draw(plot_info["tree_var"][0] + ">>hist5","LHEWeights["+str(aQGC_key[4])+"]")
        legend.AddEntry(hist5, aQGC_val[4].replace("_m"," = ").replace("p",".").replace("_0"," = 0"))
        hist5.Scale(1/hist5.Integral())
        setHistAttributes(hist5, plot_info, ROOT.kViolet,0)

    hist1.Draw()
    if len(aQGC_key) >= 2:
        hist2.Draw("sames")
    if len(aQGC_key) >= 3:
        hist3.Draw("sames")
    if len(aQGC_key) >= 4:
        hist4.Draw("sames")
    if len(aQGC_key) >= 5:
        hist5.Draw("sames")

    legend.Draw("same")
    setTDRStyle(c1, 1, 13, "No") 
    hist1.GetXaxis().SetTitle(plot_info["xlabel"])
    if plot_info["ylabel"] == "":
        plot_info["ylabel"] = "Events / %s GeV" % int(hist1.GetBinWidth(1))
    hist1.GetYaxis().SetTitle(plot_info["ylabel"])
    c1.SaveAs("test.pdf")
7

Hi,

the histos are being garbage collected. Perhaps you can use DrawClone or keep a list of them that you update in your for loop.

Cheers,
D

8

Hi,

I tried DrawClone but it was not working then I saved list of histo and it worked.

Thank you very much.

with regards,
Ram