TTree::Scan() output

Tioukov Valeri (valeri@d500na1.na.infn.it)
Tue, 13 Jul 1999 14:34:47 +0200 (MET DST)


Hi rooters,

The output of Scan() function seems to be misleading in case of
TClonesArray branch, especially then array could have 0 size.

To demonstrate it I modify in MainEvent.cxx one line:

// Int_t ntrack = Int_t(arg5 +arg5*sigmat/120.);
Int_t ntrack = ev;

In this case the first event has 0 tracks.

After producing Event.root start the macro :

zero.C
{
gSystem.Load("libEvent");

TFile f("Event.root");

for(int i=0; i<3; i++)
T->Scan("fTemperature:fFlag:fNtrack:fPx:fPy","","",i+1);
}

The output is:
root [0] .x zero.C
************************************************************************
* Row *fTemperature * fFlag * fNtrack * fPx * fPy *
************************************************************************
* 0 * 20.319 * 0 * 0 * 0 * 0 *
************************************************************************
************************************************************************
* Row *fTemperature * fFlag * fNtrack * fPx * fPy *
************************************************************************
* 0 * 20.319 * 0 * 0 * 0 * 0 *
* 1 * 20.041 * 0 * 1 * -0.52418 * 1.8685 *
************************************************************************
************************************************************************
* Row *fTemperature * fFlag * fNtrack * fPx * fPy *
************************************************************************
* 0 * 20.319 * 0 * 0 * -0.52418 * 1.8685 *
* 1 * 20.041 * 0 * 1 * -0.52418 * 1.8685 *
* 2 * 20.297 * 0 * 2 * 0.26634 * 0.052835 *
************************************************************************

First question: fPx and fPy variables are printed only for 1-st track.
How to print them for all tracks?

Second question: for the 1-st event (0-entry) fPx and fPy do not
defined because this event have no tracks, but there printed !?

I paw the output of nt/scan is exactly as the expected - nothin
printed in case of 0 tracks, everithing - in case of many tracks:

nt/scan 7100 ! ! ! ! idev ntr day daz
+-------+-------------+-------------+--------------+--------------+
| Event | idev | ntr | day | daz |
+-------+-------------+-------------+--------------+--------------+
| 403 | 4116 | 0 | | |
| 404 | 4172 | 0 | | |
| 405 | 65 | 1 | 0.004 | -0.002 |
| 406 | 66 | 1 | 0.001 | -0.002 |
| 407 | 69 | 1 | 0.002 | 0.003 |
....
| 535 | 366 | 2 | | |
| * 1 | | | 0. | -0.025 |
| * 2 | | | -0.01 | -0.001 |
| 536 | 423 | 2 | | |
| * 1 | | | 0.021 | 0.009 |
| * 2 | | | 0.009 | -0.009 |

Regards
Valeri