Incorrect information in jupyROOT 2d histograms

Newbie
1

The hover information for bin in interactive 2D histograms in jupyter lab (jupyROOT) seems to be pythonic rather than ROOT/C++ (See attached screenshot).
Unless, I am mistaken, the first bin in ROOT should be indexed as Bin 1 not Bin 0. If we query the LowEdge for bin 0 in ROOT, then it says -1 and not 0 as given by the hover information bubble.
This bahviour is not present for 1D histograms. Also, if I save the histogram in a .root file and open with TBrowser, it shows the bin indexing according to ROOT convention.

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_ROOT Version: ROOT 6.24/06
_Platform: Ubuntu
Compiler: Not Provided

2

Hi,

Can you provide data saved in ROOT file?

Regards,
Sergey

3

This is just some code I wrote to investigate this behaviour from jupyroot. You can reproduce this behaviour by running this code in jupyterlab:

from ROOT import *
import numpy as np

%jsroot

arr_0 = np.array([1,2,3,4,5,6,7])

arr_root2d = TH2F("sample_hist_2d", "Hist_title", 10, 0, 10, 10, 0, 10)

for myindexi, myelement in enumerate(arr_0):
    for myindexj, myelement in enumerate(arr_0):
        arr_root2d.SetBinContent( arr_root2d.GetBin(myindexi + 1, myindexj + 1), myelement)

C7 = TCanvas()
arr_root2d.Draw('colz')
C7.Draw()

More information on jupyter version:

jupyter_client 7.3.4
jupyter_core 4.10.0
jupyter_server 1.17.1
jupyterlab 3.3.2
jupyterlab_pygments 0.2.2
jupyterlab_server 2.12.0

4

Now I see.

In JSROOT tooltips bins numbering starts from 0 - not from 1.
One should increase it by 1 to use in TAxis::GetBinLowEdge.

I will fix it in next JSROOT versions.
Thanks to reporting it!

1 Like
5

Ok but does that mean it only affacts the 2D plots? 1D histograms seem to be unaffected by this bug.

6

Yes, it was problem in 2D plots. Now it is fixed in JSROOT master branch.

7

OK, thanks.