Re: TH3 constructors with both constant and variable bin widths...

Pierre-Luc,

I was wrong, what you propose with a subsequent call to TAxis::Set should work.

Rene Brun

Pierre-Luc Drouin wrote:
> I'm not sure to understand why this wouldn't work... I looked at the
> different constructors and the only difference I see is through the
> calls of TAxis::Set. TAxis seems to distinguish between constant bin
> width and variable binwidth though TArrayD.fN, which is set to a
> non-zero value only by TAxis::Set(Int_t, Double_t*). The following
> example seems also to produce the right result:
>
> Double_t bins[]={0,1,2.5,3,4,5,6,7,8,9,10};
> Int_t nbins=10; TH2F
> th("th","th",10,0,10,10,0,10);
> th.GetXaxis()->Set(nbins,bins) th.Fill(2.25,1.5);
> th.Draw();
>
> Thank you!
> Pierre-Luc Drouin
>
> Rene Brun wrote:
>> No, this cannot work (see possible constructors in TH3.h).
>> I can only repeat my previous suggestion to use THnSparse if you want
>> variable bin width only on one or two axes.
>>
>> Rene
>>
>> Pierre-Luc Drouin wrote:
>>> I think I might have found a solution. If I want to define a TH3D
>>> having only variable bin width for the x axis, could I simply do the
>>> following?
>>>
>>> Double_t nbins=10;
>>> Double_t bins[]={0,1,2,3,4,5,6,7,8,9,10};
>>> TH3F th("th","th",nbins,bins[0],bins[nbins],10,0,10,10,0,10);
>>> th.GetXaxis()->Set(nbins,bins);
>>>
>>> Thank you!
>>> Pierre-Luc Drouin
>>>
>>> Rene Brun wrote:
>>>> Pierre-Luc,
>>>>
>>>> I suggest to use THnSparse instead of TH3
>>>>
>>>> Rene Brun
>>>>
>>>> Pierre-Luc Drouin wrote:
>>>>> Hi,
>>>>>
>>>>> I would like to know if there is a particular reason why there is
>>>>> no TH3 constructor having both constant and variable bin widths.
>>>>> This would be nice to be able avoiding binary searches for TH3*
>>>>> objects like it is the case for TH2*, when only some of the axes
>>>>> have a variable bin width...
>>>>>
>>>>> Thank you!
>>>>> Pierre-Luc Drouin
>>>>>
>>>>
>>>
>>
>
Received on Thu Jul 17 2008 - 16:58:18 CEST