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 >
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