Christoph Borgmeier wrote: > > Hello, > > I just ran into the same problem as Wei Xie did last year: An existing > histogram has to be overwritten. I do not want to delete it and copy > constuct a new one, since it is attached to lists. I have only a TH1 > pointer, while the histogram is of type TH1F or TH2F (or maybe something > else). > Hi Christoph, What do you want to do exactly? You can do all sorts of operations with an histogram: TH1::Reset() TH1::Add to replace its contents by another histogram contents Also note that you can detach an histogram from a directory by calling TH1::SetDirectory(0) Rene Brun > Fons Rademakers wrote on 25 Jun 1998: > > use either the histogram TH1::operator=() or the TH1::Copy() > > or the TObject::Clone() methods. > > > > Cheers, Fons. > > > > Wei Xie wrote: > > > > > > Dear ROOTers' > > > > > > Is there a way to copy one histogram directly to another > > > histogram ? > [...] > > As far as I understand it, > > * TH1::operator does not copy the entire object (no polymorphism > possible), > > * TH1::Copy() is protected, > > * TObject::Clone() creates a new object in a different memory location. > > Do I miss the point here? Do I have to use memcpy (*shudder*)? > > Thank you for your answer > Christoph > > -- > Christoph Borgmeier Mail: DESY F15/HERA-B, Geb. 61/117 > Notkestr. 85, 22607 Hamburg > Humboldt Univ Berlin Phone: +49 40 8998 4850 > Email: Christoph.Borgmeier@desy.de
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