How to scale Axis Tick Mark Label after RebinX()

[ajaydeo]

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ROOT Version: 6.17/01
Platform: linuxx8664gcc
Compiler: gcc version 8.3.1 20190223

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Hello,

I have a 1-Dimensional histogram, say h1 with bins going from 0 to 4000. The X-axis tick-mark labels are
in the interval of 1000 i.e. 0,1000,2000,3000,4000

Now, I rebin X-Axis using

h1->RebinX(10)

After this operation the X-axis tick-mark labels are still the same i.e. 0,1000,2000,3000,4000

I want these to change to 0,100,200,300,400 since the calibration of the axis is also changed now. I am not able to get this behaviour.

I tried to search for the answer on the ROOT Forum but the search did led to to relevant post. Also, I am sorry, if this sounds a very simple question.

Regards,

Ajay

[Wile_E_Coyote]

Can we shift histogram for several channels?

I’m not sure if this is fully kosher, but suit yourself : #include "TAxis.h" #include "TH1.h" #include "TArrayD.h" Double_t ScaleX(Double_t x) { Double_t v; v = 10 * x + 100; // "linear scaling" function example return v; } Double_t ScaleY(Double_t y) { Double_t v; v = 20 * y + 200; // "linear scaling" function example return v; } Double_t ScaleZ(Double_t z) { Double_t v; v = 30 * z + 300; // "linear scaling" function example return v; } void ScaleAxis(TAxis *a, Double_t (…

[ajaydeo]

Thank you very much! It is working!

But isn’t there a simple way to achieve it? We need this functionality quite frequently with different scaling factors. This means - I have to edit the macro everytime before using it. Isn’t it?

What I was doing was following:

root [0] .L ScaleAxes.cxx++
root [1] .L ../can2root_utils_cc.so //"can2root_utils.cc stores several macros
root [2] loadF("CtrdShftAna.root");
root [3] td662Vs377_278_bgsub->RebinX(10);
root [4] ScaleXaxis(td662Vs377_278_bgsub, ScaleX);
root [5] td662Vs377_278_bgsub->Draw();
root [6] td662Vs377_278_bgsub->ResetStats();

With the above I achieve what I wanted to by changing v = 10 * x + 100; to v = 0.1 * x + 100; in the original macro in Double_t ScaleX(Double_t x) function.

It would have been great to use a scaling factor at root [4] instead of using ScaleX.

I hope I was using it as it is intended.

With best regards,

Ajay

[Wile_E_Coyote]

If the x-axis is a “fix bin size” one then this should be enough:

your_histogram->GetXaxis()->SetLimits(new_x_min, new_x_max);
your_histogram->ResetStats();

[ajaydeo]

Perfect! This is what I was looking for. Thank you once again.