Hi Rene,
yes, this is what we would like to have. Sorry for my poor description.
Just two additional clarifications:
- The operator [] should also work in selections:
mytree.Draw("somethingElse","myEventBits[10]");
- Not only calling mytree.Draw("myEventBits"); should produce this
histogram, but also clicking on the variable in the TBrowser.
Cheers,
Birger
On Thu, 31 Oct 2002, Rene Brun wrote:
> Hi Birger,
>
> Let see if I understand correctly your request.
>
> - you are requesting an operator [] to get the ith bit in a TBits
> instead of calling the function TestBitNumber().
> That is quite easy to implement. I propose in this case
> a read only operator [].
>
> - you want to do mytree.Draw("myEventBits");
> This will automatically loop on all your events and filling
> an hitogram with as many channels as there are bits in TBits
> and where the bin count is incremented by 1 or the specified weight
> for each event where the corresponding bit is set.
> This requires a bit more work, but I agree would be a nice addition.
>
> Rene
>
> On Thu, 31 Oct 2002, Birger Koblitz wrote:
>
> > Hi Rene,
> >
> > I think Ursula Berthon already talked to you about this at the
> > Root-Meeting:
> >
> > Within H1 we would like to be able to put bit-arrays into our HAT tree
> > which should be accessible using only a browser and which is used for
> > event selection. Currently TBits allows to use the member function
> > TestBitNumber() which is quite inconvenient if it comes to a selection of
> > a large number of status bits e.g. to check if the quality of an event is
> > good. This could easily go over the maximum selection length of a tree.
> > Therefore it would be nice if one could simply use bits[i] to check the
> > ith bit in TBits bits. In addition it would be nice if one could view a
> > bit-array in a TBrowser. It should show a histogram over the bits and the
> > number of entries per bit. Currently fAllBits shows the entries (in 2^i
> > form) for the lowest byte. I think this is not really useful.
> >
> > In the moment we are using byte-arrays which at least allow to use the []
> > operator and allow us to inspect one bit with the TBrowser. H1 would be
> > very intersted to move to TBits because currently the bit-arrays make up
> > most of our HAT ntuple, we would be even willing to move to a newer
> > root-version ;-)
> >
> > Cheers,
> > Birger
> >
> > ------------------------------------------------------------
> > Birger Koblitz koblitz@mail.desy.de
> > MPI für Physik
> > c/o DESY-FH1 Tel: +49 40 8998-2431
> > Notkestr. 85 Fax: +49 40 8998-3094
> > D-22603 HAMBURG
> >
>
>
------------------------------------------------------------
Birger Koblitz koblitz@mail.desy.de
MPI für Physik
c/o DESY-FH1 Tel: +49 40 8998-2431
Notkestr. 85 Fax: +49 40 8998-3094
D-22603 HAMBURG
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