Re: [ROOT] Multiple booking

From: Robert Zitoun (zitoun@fnal.gov)
Date: Thu Nov 29 2001 - 18:46:13 MET


  Thank you Peter

Your idea is very good. I tried it and worked fine AND QUITE INSTANTLY!

  Still, Rene

I am running on a slow but "big" D0 machine (d0mino). Booking a 2D with
50000*15 channels should take as much page swapping as 50000
1D's. Shouldn't it ?

                         Robert

On Thu, 29 Nov 2001, Peter Skensved wrote:

>       Robert,
>   Have you touught about using a singel TH2F instead and projecting out
the `channel' 
> in question ?
> 
>  Something like 
> 
> TH2F *h = new  TH2F( "h", "", 15, 0, 15, 50000, 0 )
> 
> and
> 
> h->ProjectionX("", 277,277 )->Draw()   to get `channel' 277
> 
>                                                        peter
> 
> ----
> 
> Peter Skensved                          Email : peter@SNO.Phy.QueensU.CA
> Dept. of Physics,                       Phone:  (613) 533-2676
> Queen's University,                     Fax:    (613) 533-6813
> Kingston, Ontario,
> Canada
> 

> On Wed, Nov 28, 2001 at 04:25:10PM -0600, Robert Zitoun wrote:
> > 
> >   Hi Rooters
> > 
> >  I am trying to book 50,000 histograms in a macro doing
> > 
> > TH1F *h[50000];
> > char text[100];
> > 
> >   for( int chan=0 ; chan<50000 ; chan++ )
> >   {
> >     sprintf(text, "h%d", chan);
> >     h[chan] = new TH1F( text, "", 15, 0, 15);
> >   }
> > 
> > It take me 20 minutes to get histos booked. The booking time for one
> > histogram increased with its ordinal number (quite fast in the beginnig,
> > verrry slow for the last ones). I even used a compiled version to get it
> > done in 20'.
> > 
> >  There is certainly a more clever (faster) way to do it. Can you tell me ?
> > Also can you tell why what it did is so long.
> > 
> >                   Thank you
> > 
> >                                  Robert Zitoun, Stony Brook and Annecy

> 



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