Selector speed

I've noticed that my selector run much slower than a single variable |Draw|. There are lots of variables (and lots of events).

Would it speed it up to not do |SetBranch|, etc. for variables I'm not using?

-Art

A.E. Snyder, The Former Group C (TFC)        \!c*p?/
SLAC Mail Stop #95                          ((.   .))
Box 4349                                        |
Stanford, Ca, USA, 94309                      '\|/`
e-mail:snyder_at_slac.stanford.edu                 o
phone:650-926-2701                              _
http://www.slac.stanford.edu/~snyder          BaBar
FAX:707-313-0250                          Collaboration
                                                 &
                                            Fermi/GLAST

On Tue, 13 Sep 2011, Philip Rodrigues wrote:

> Here is my favourite example of the confusing behaviour of TH1::GetMean():
>
> root [0] TH1F* h2=new TH1F("foo2", "bar", 10, 0, 5)
>
> root [1] h2->Fill(2.2)
>
> root [2] h2->GetMean()
> (const Double_t)2.20000000000000018e+00
>
> // This excludes a zero bin, so shouldn't affect the mean:
> root [3] h2->GetXaxis()->SetRangeUser(-1, 3.8)
>
> root [4] h2->GetMean()
> (const Double_t)2.25000000000000000e+00
>
> On Tuesday, September 13, 2011 04:16:05 PM Arthur E. Snyder wrote:
>> Stefan and Aammer:
>>
>>
>> What would be nice would be an option, e.g., GetMean("binned") vs.
>> GetMean("unbinned") with default being what folks are used to.
>>
>> I suspect that problem occurs not just for subtracted historgrams but for
>> weighted ones.
>>
>> On the other hand sometimes you want the unbinned mean. If you've made big
>> bins to make the plot look nice, the mean may be seriously over estimated
>> by using middle of the bin ...
>>
>> Maybe there should be a warning when |h->Sumw2()| has been involked ...
>>
>> -Art S.
>>
>> A.E. Snyder, The Former Group C (TFC) \!c*p?/
>> SLAC Mail Stop #95 ((. .))
>> Box 4349 |
>> Stanford, Ca, USA, 94309 '\|/`
>> e-mail:snyder_at_slac.stanford.edu o
>> phone:650-926-2701 _
>> http://www.slac.stanford.edu/~snyder BaBar
>> FAX:707-313-0250 Collaboration
>> &
>> Fermi/GLAST
>>
>> On Tue, 13 Sep 2011, Stefan Piperov wrote:
>>> This issue - that ROOT reports histogram's momenta based on unbinned
>>> data - has been discussed several times now, but without much
>>> consequences...
>>>
>>> It is plain wrong, of course, to report quantities related to the
>>> initial dataset as belonging to the histogram, but this is how ROOT was
>>> designed from the very beginning, so it's too late now to change, I
>>> guess. What we can do, though, is to spread the word, so that at least
>>> the users know of this problem, and do not rely on TH1::GetMean() to get
>>> the mean of the binned data.
>>>
>>> Stefan.
>>>
>>> On Tue, 13 Sep 2011, Arthur E. Snyder wrote:
>>>> Aamer,
>>>>
>>>> It doesn't work on subtracted histograms. I had to 'roll-my-own' to do
>>>> that (though there might be something existing that does this that I
>>>> just didn't find).
>>>>
>>>> As I recall |root] does unbinned mean, so you get the same result
>>>> regardless of binning. It's not clear what it does the case of
>>>> subtracted histograms, but if the histograms is asymmetric the result
>>>> can be wildly wrong.
>>>>
>>>> -Art S.
>>>>
>>>> A.E. Snyder, The Former Group C (TFC) \!c*p?/
>>>> SLAC Mail Stop #95 ((. .))
>>>> Box 4349 |
>>>> Stanford, Ca, USA, 94309 '\|/`
>>>> e-mail:snyder_at_slac.stanford.edu o
>>>> phone:650-926-2701 _
>>>> http://www.slac.stanford.edu/~snyder BaBar
>>>> FAX:707-313-0250 Collaboration
>>>>
>>>> &
>>>>
>>>> Fermi/GLAST
>>>>
>>>> On Tue, 13 Sep 2011, Aamer Wali Rauf wrote:
>>>>> Hi,
>>>>> I have always assumed (and thus used) that the TH1::GetMean(1) method
>>>>> gives out the weighted mean value
>>>>> of the x-axis of the histogram. Visibly it looks to me that way but is
>>>>> it really so? Can someone
>>>>> comment on that please?
>>>>>
>>>>> Thanks in advance,
>>>>> Aamer
>>>
>>> *---------------------------------------------------------------------*
>>>
>>> Stefan Piperov Mail: FNAL P.O.Box 500, MS 205, Batavia, IL-60510
>>> Phone: (630) 840-5176 E-Mail: piperov_at_fnal.gov
>>>
>>> *---------------------------------------------------------------------*
>>> "Give a skeptic an inch... and he'll measure it."
>
>
Received on Fri Jan 13 2012 - 22:01:12 CET