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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