Issue with multiple drawing of TH2 using custom binning with different option (marker,colz) in logz!

ROOT
1

Hello,

Sorry for the long title, which try to describe a very specific bug I am dealing with: I am drawing two TH2 histo superposed each having a custom binning, the first one with “col2z” option and the second one with “same” (markers). The second histo is visible in linear Z scale, but disappear when switching to LOGZ. This is however working fine when using regular histogram (linear binning), and so this looks to be proper to TH2 when using a custom binning (logarithmic in my case). ROOT version is 5.34/14 and an example is attached bellow.

Is it known and is there eventually a way to fix it ?

canvas without LOGZ

th2-not-log.png696×472 6.6 KB

canvas with LOGZ

th2-log.png696×472 5.96 KB

2

can you post an example reproducing the problem ?

3

Hi,

Today I encountered same issue,
I compiled a tiny demo program to reproduce the issue, and contrary to my expectation it worked well,
it is the file named “testLogz.C”.

Then I made another simple code which is closer to what I am doing, i.e. reading histograms
from the root file, and then draw them on top of each other one with colz, the other is a scatter plot with a certain marker type and color.
This time I was able to reproduce the issue.
The plots demonstrating the issue, as well the root file and the code (“testLogz2.C”) are attached.

  • Root Version 6.16/00
  • Ubuntu 18.04

Thank you,
Rafo

testWithLogZ
testWithLogZ.png948×921 12.8 KB

testWithLinZ
testWithLinZ.png948×921 21.8 KB

testLogz2.C (536 Bytes) EvSelectionCutHists_Data.root (70.4 KB) testLogz.C (515 Bytes)

4

I see,
I need to check. Your second histogram is flat (at 1) that might be the reason why the scatter plot does not show. Meanwhile You can use an other box:

{
   TCanvas *c1 = new TCanvas("c1", "", 950, 950);

   TFile *file_in = new TFile("EvSelectionCutHists_Data.root", "Read");

   TH2D *h_dX_Top_PosWithL6     = (TH2D*)file_in->Get("h_dX_Top_PosWithL6");
   TH2D *h_dX_Top_PosWithL6_Cut = (TH2D*)file_in->Get("h_dX_Top_PosWithL6_Cut");
   h_dX_Top_PosWithL6_Cut->SetLineColor(2);

   c1->SetLogz();

   h_dX_Top_PosWithL6->Draw("colz");
   h_dX_Top_PosWithL6_Cut->Draw("box same0");
}

58
Screenshot 2020-02-13 at 10.33.58.jpg1620×1362 412 KB

5

Thank you!,

the box also will work, though, I would like markers, if that would be possible.

Also with the box I had to artificially scale the _Cut histogram with a big number.
For some reason it changed the frame color, and the “_Cut” histogram didn’t draw (probably box size was too small).

Did it work for you, or you also have scaled it?

6

note you need “same0”

7

Yes, I am using “same0” option,
This is done with your snipped.
As you can see for some reason it changed the Frame color without drawing the “_Cut” histogram

image
image.png931×854 12.5 KB

8

can you post the code ?

9

It is the same code, that you posted earlier today,

{
   TCanvas *c1 = new TCanvas("c1", "", 950, 950);

   TFile *file_in = new TFile("EvSelectionCutHists_Data.root", "Read");

   TH2D *h_dX_Top_PosWithL6     = (TH2D*)file_in->Get("h_dX_Top_PosWithL6");
   TH2D *h_dX_Top_PosWithL6_Cut = (TH2D*)file_in->Get("h_dX_Top_PosWithL6_Cut");
   h_dX_Top_PosWithL6_Cut->SetLineColor(2);

   c1->SetLogz();

   h_dX_Top_PosWithL6->Draw("colz");
   h_dX_Top_PosWithL6_Cut->Draw("box same0");
}
10

it gives me:

13
131696×1764 482 KB

11

Ok, thank you for checking.

perhaps it is from my Root version then, or related to my OS, or maybe something else.
Anyway it is not hard for me to scale it, and doesn’t affect the analysis, so I am good,

Thank you,
Rafo