GetMaximumBin

ROOT
1

HI,
I declare a histogram in the following way:

Double_t e_nu[7]={5,7,10,14,18,22,30};
Double_t x_nu[14]={0.0001,0.03,0.06,0.1,0.15,0.20,0.25,0.30,0.40,0.50,0.60,0.70,0.80,0.90};
Double_t y_nu[9]={0.05,0.20,0.30,0.40,0.50,0.60,0.70,0.80,0.95};

TH3F *nu_reco_total = new TH3F(“nu_reco_total”,“total nu’s(reco)”,6,e_nu,13,x_nu,8,y_nu);

after filling the histogram, I try doing :
cout<<nu_reco_total->GetMinimumBin()<<" "<<nu_reco_total->GetMaximumBin()<<endl;

and I get the answer:
133 and 1030

I dont quite understand the answer, how are these numbers related to the Minimum or MaximumBin ?
Also what should I do if I want to get the minbin and maxbin in each of the x,y and z axes?
-thanks debdatta.

2

There are two functions that you can use to return the bin number having
the max or min content

Int_t TH1::GetMaximumBin() const Int_t TH1::GetMaximumBin(Int_t &locmaxx, Int_t &locmaxy, Int_t &locmaxz) const
In case of a 3-d histogram, it is better to use the second form that returns
(locmaxx, locmaxy, locmaxz).
The first form returns one single number that contains the compact information of locmaxx,locmaxy,locmaxz

Rene

3

Hi Rene,
thanks for your reply. I am still a little confused.

Int_t TH1::GetMaximumBin(Int_t &locmaxx, Int_t &locmaxy, Int_t &locmaxz) const

with this command, how do I get the locmaxx etc. initialised ? I apologise if I am missing something obvious.

                        -regards Debdatta.
4

locmaxx,locmaxy,locmaxz are 3 output parameters. Do

Int_t locmaxx,locmaxy,locmaxz; hist.GetMaximumBin(locmaxx,locmaxy,locmaxz); //and now use locmaxx, etc
Rene

5

Double_t e_nu[7]={5,7,10,14,18,22,30};
Double_t x_nu[14]={0.0001,0.03,0.06,0.1,0.15,0.20,0.25,0.30,0.40,0.50,0.60,0.70,0.80,0.90};
Double_t y_nu[9]={0.05,0.20,0.30,0.40,0.50,0.60,0.70,0.80,0.95};

TH3F *nu_reco_total = new TH3F(“nu_reco_total”,"",6,e_nu,13,x_nu,8,y_nu);

I tried:

Int_t locminx,locminy,locminz,locmaxx,locmaxy,locmaxz;

nu_reco_total->GetMinimumBin(locminx,locminy,locminz);
nu_reco_total->GetMaximumBin(locmaxx,locmaxy,locmaxz);

cout<<"min “<<locminx<<” “<<locminy<<” "<<locminz<<endl;
cout<<"max “<<locmaxx<<” “<<locmaxy<<” "<<locmaxz<<endl;

I see:
min 1 1 1
max 1 1 1

I tried getting the bins before “filling” the histogram, but I think it shouldn’t matter. I think I am doing something wrong.

                           -thanks debdatta.
6

I am totally confused by your question.
Do you want the bin with the minimum or maximum content?
or the minimum , maximum of the x,y axis ?

My previous answer was assuming the first case. If you meant the second case use e_nu[0], x_nu[0], etc

If none of these cases, please rephrase your question.

Rene

7

HI Rene,
I got a little confused too. I thought by calling MaximumBin I will get the “last” bin in the x-axis and not the bin having the “maximum” number of entries. It took me a while to figure that out. Thank you for your patience.

                                 -regards Debdatta.