Re: One Histogramm

Otto Schaile (Otto.Schaile@Physik.uni-muenchen.de)
Fri, 19 Mar 1999 09:31:49 +0100 (MET)


On Thu, 18 Mar 1999, Alexey Pavlinov wrote:

> Dear Rooters,
> to memory and close file. After closing all histogramms
> disappear from memory. This action isn't problem in PAW.
> Is this the problem for ROOT or no?
>
Hi Alexey,
after opening a TFile the histgrams still belong to the directory
space of TFile. As long TFile exists you can use them. If
TFile disappears the hists disappear.

To keep them in memory you have to add them to the directory
in memory. This can be done as follows:

TFile * f = new TFile("hfile.root");
TH1 * hist = (TH1*)f->Get("myhist");
hist->SetDirectory(gROOT);
f->Close();

Cheers
Otto

----------------------------------------------------------------------------
Otto Schaile Sektion Physik der LMU Muenchen
Phone: (+49 89)289 14070 Am Coulombwall 1, D-85748 Garching, Germany
FAX: (+49 89)289 14072 EMail: Otto.Schaile@Physik.Uni-Muenchen.DE