Scaling y-axis for histograms with error bars and empty bins

ROOT
1

Let assume I have histogram with N numbers of bins, but only k of the is filled with value and error bars, rest is untouched.

Now I am drawing it. The Y axis starts at 0, because of empty bins, upper range is calculated to fit histogram.

Now my question: what is the effective way to draw such histogram in the way that empty bins are not influencing y-scaling (do not force y-axis starting at 0).

One solutin is to use SetRangeUser and determine range by hand. How? Do I need to iterate bin-by-bin reading out content and error and calculating range by hand? is there some faster way? It must be somehow done for upper range of the histogram, but I could not dig into this in the code.

Using TGraph is also not an option since for unused points it also draw point at (0,0).

Rafał

2

Why don’t you do h->SetMinimum(yyy) ?

3

But I don’t know minimum, histograms are filled wit hdata, so I must find minimum by hand first.

4

Here:

root.cern.ch/root/htmldoc/TH1.h … GetMinimum

One can read:

5

I know this, but I have also error bars, and lowest bin content does not mean that lower boundar of the bin is also smallest. So I guess there is no straight way than just iterating and checking manually.

Maybe would be usefull to add drawing optin for TH1 which ignores empty bins (no data, no error).

6

Ok, A quick loop on the histogram errors and bins contain and errors will do the job. No need for a special option.