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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