Add a legend on a 2D histogram, including TProfile

[atha.stam]

I am creating a 2D histogram and I would like to make a legend of it.
On the same canvas I am drawing a TProfile of the histogram and I would like it to be on the legend.
However although I can get the entry, the colout doesn’t match, which is the case when plotting other functions as well.

My code is

[code]TH2F* mean_Gamma_Flash() {
gStyle->SetPalette(52); //Use Grayscale palette–51-59

//Load File.
TFile *f = new TFile(“FIMG5_300.root”);

//Loop over each histogram and store pointer in vector.
std::vector<TH1F*> hists;
for (int i=0;i<305;i++) {
TH1F hIndv = (TH1F)f->Get(Form(“FIMG5_EV_%d;1”,i));
if (hIndv)
hists.push_back(hIndv);
}

//Compute average
TH2F *hAvg = Average(hists);
TH2F *hThres = GetThreshold(hAvg,5);
TProfile *hProf = hThres->ProfileX(“hProf”);//Average histogram From cut histogram
TProfile *hProfFull = hAvg->ProfileX(“hProfFull”);//Average histogram From Full histogram
TH1F *hFreq = GetFrequent(hAvg);
TH1F *hFreqThres = GetFrequent(hThres);

//Turn off stats
hAvg->SetStats(kFALSE);

//Draw the 2D hist with the average prof on top.
hProf->SetLineColor(kRed);
hProf->SetMarkerColor(kRed);
hProfFull->SetLineColor(kGreen+1);
hProfFull->SetMarkerColor(kGreen+1);
hFreq->SetLineColor(kBlue);
hFreqThres->SetLineColor(kCyan);
hAvg->Draw(“COLZ”);
hThres->Draw(“COLZ”);
hProf->Draw(“SAME”);
hFreq->Draw(“SAME”);
hFreqThres->Draw(“SAME”);
hProfFull->Draw(“SAME”);

//Use a log scale in Z
gPad->SetLogz();
gPad->Update();

TString histfilename = "mean_gamma.txt";
SingleExportAscii(hProf,histfilename);

leg = new TLegend(0.6,0.1,0.9,0.4);
leg->AddEntry(hAvg,“2D-Stack”);
leg->AddEntry(hThres,“2D-Stack after cut”);
leg->AddEntry(“hProFull”,“Mean Value without cut”);
leg->AddEntry(“hPro”,“Mean Value with cut”);
leg->AddEntry(“hFreq”,“Most Frequent Value”);
leg->Draw();

return hAvg;
}

TH2F Average(std::vector<TH1F> hists) {
TH2F *hAvg = new TH2F(“hAvg”,“Avg”,8000,0,8000,300,0,300);
for (size_t i=0;i < hists.size(); i++) {
for (int bin = 0; bin < hists[i]->GetNbinsX(); bin++) {
int resultBin = hAvg->FindBin(bin, hists[i]->GetBinContent(bin));
int binContent = hAvg->GetBinContent(resultBin) + 1;
hAvg->SetBinContent(resultBin,binContent);
}
}
return hAvg;
}

TH1F* GetFrequent(TH2F* hist2D) {
TH1F* hFreq = new TH1F(“hFreq”,“Freq”,hist2D->GetNbinsX(),hist2D->GetXaxis()->GetBinLowEdge(1),hist2D->GetXaxis()->GetBinLowEdge(hist2D->GetNbinsX()) + hist2D->GetXaxis()->GetBinWidth(hist2D->GetNbinsX()));

for (int xBin = 1; xBin <= hist2D->GetNbinsX(); ++xBin) {
double maxYBin = 0;
for (int yBin = 1; yBin <= hist2D->GetNbinsY(); ++yBin) {
if (hist2D->GetBinContent(xBin,yBin) > hist2D->GetBinContent(xBin,maxYBin)) maxYBin = yBin;
}
hFreq->SetBinContent(xBin,maxYBin);
}
return hFreq;
}

TH2F* GetThreshold(TH2F* hist2D, int threshold) {
//TH2F* hThres = hist2D->Clone();
TH2F* hThres = new TH2F(*hist2D);
for (int xBin = 1; xBin <= hist2D->GetNbinsX(); ++xBin) {
for (int yBin = 1; yBin <= hist2D->GetNbinsY(); ++yBin) {
if (hist2D->GetBinContent(xBin,yBin) < threshold) hThres->SetBinContent(xBin,yBin,0);
}
}
return hThres;
}[/code]

In particular my legend code is

leg = new TLegend(0.6,0.1,0.9,0.4); leg->AddEntry(hAvg,"2D-Stack"); leg->AddEntry(hThres,"2D-Stack after cut"); leg->AddEntry("hProFull","Mean Value without cut"); leg->AddEntry("hPro","Mean Value with cut"); leg->AddEntry("hFreq","Most Frequent Value"); leg->Draw();

My output is the following

Any idea on how to create a proper legend?

[couet]

From
root.cern.ch/root/htmldoc/TLegend.html
note:

Each item in the legend is added using the AddEntry method. This method defines the object to be added (by reference or name), the label associated to this object and an option which a combination of:

L: draw line associated with TAttLine if obj inherits from TAttLine
P: draw polymarker associated with TAttMarker if obj inherits from TAttMarker
F: draw a box with fill associated wit TAttFill if obj inherits TAttFill
E: draw vertical error bar

also try to use the object pointer instead of its name in AddEntry

Which root version are you using ?

[atha.stam]

Thank you for your answer.
I am using version 5-34-19-251 in lxplus.

The way I create the mean value is using TProfile, which creates a TH1.
My code to create them is the following

TProfile *hProf = hThres->ProfileX("hProf");//Average histogram From cut histogram TProfile *hProfFull = hAvg->ProfileX("hProfFull");//Average histogram From Full histogram

The way I create the legend is the following

leg = new TLegend(0.6,0.1,0.9,0.4); leg->AddEntry("hProFull","Mean Value without cut"); leg->AddEntry("hPro","Mean Value with cut"); leg->AddEntry("hFreq","Most Frequent Value"); leg->Draw();

If I replace “hProFull” with hProFull I get an error that

Symbol hProFull is not defined in current scope

[couet]

Can you provide a small running macro reproducing the issue ?

[atha.stam]

A working code is the following

[code]#include “Riostream.h”
#include
#include
#include “TH1F.h”
#include “TH2F.h”
#include “TProfile.h”

TH2F* test_legend() {
TCanvas *c1 = new TCanvas(“c1”, “c1”,900,900);
gStyle->SetOptStat(0);

// Create, fill and project a 2D histogram.
TH2F h2 = new TH2F(“h2”,"",40,-4,4,40,-20,20);
Float_t px, py;
for (Int_t i = 0; i < 25000; i++) {
gRandom->Rannor(px,py);
h2->Fill(px,5py);
}
TProfile * profh2X = h2->ProfileX(“profX”);
profh2X->SetLineColor(kRed);
TProfile * profh2Y = h2->ProfileY(“profY”);
profh2Y->SetLineColor(kBlue);

h2->Draw(“COLZ”);
profh2X->Draw(“SAME”);
profh2Y->Draw(“SAME”);

leg = new TLegend(0.6,0.1,0.9,0.4);
leg->AddEntry(profh2X,“Red Line”);
leg->AddEntry(profh2Y,“Blue Line”);
leg->Draw();

return h2;
}[/code]

I found out what was wrong…
I named my histograms “hProf” but I was adding in the legend “hPro”…
Such a stupid mistake…

Thank you very much for your time and sorry for the inconvenience!

[couet]

I found out what was wrong…

good