Hi Birger,
On Thu, 31 Oct 2002, Birger Koblitz wrote:
> 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]");
>
Yes, this was implicit in my previous mail. In the selection, mask
operations should also be supported, eg
mytree.Draw("somethingElse","myEventBits & 0x3ff");
> - Not only calling mytree.Draw("myEventBits"); should produce this
> histogram, but also clicking on the variable in the TBrowser.
Yes, it is the same logic. TBrowser calls TTree::Draw.
OK, we will implement this logic. Could you send me a small TTree file
(not HAT file) that we could use to test the new feature?
Rene Brun
>
> 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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