Hi Robert,
a TH2F with 50000*15 channels will occupy about 34 MBytes
a TH2S with the same number of channels will occupy only 17 Mbytes.
May be this is enough for you (and may be even a TH2C)
50000 TH1F with 15 channels each will occupy more space (about 40 MBytes),
because each histogram has the overhead of the axis, titles, etc.
Rene Brun
Robert Zitoun wrote:
>
> 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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