Note: The following code was taken directly from
RootTreeAnalysis in the RootAnalysis package stored in Offline's CVS repository.
In this context, the variable, evt, is a DigiEvent object which was filled in
RootTreeAnalysis::Go( ) method. All file handling is done within the
initialization of the RootTreeAnalysis object and is not shown here.
The complete documentation of the digiRootData library which
defines DigiEvent and all digitization (detector) classes can be found at:
http://confluence.slac.stanford.edu/display/WB/digiRootData
| Code Snippet | Description |
| void
RootTreeAnalysis::DigiCal() { // Purpose and Method: Process on CAL digi event const TObjArray* calDigiCol = evt->getCalDigiCol(); if (!calDigiCol) return; Int_t nCalDigi = calDigiCol->GetEntries(); ((TH1F*)GetObjectPtr("CALDIGICOUNT"))->Fill((Float_t)nCalDigi); Int_t nLayer[8]={0,0,0,0,0,0,0,0}; Float_t eLayer[8]={0.,0.,0.,0.,0.,0.,0.,0.}; Float_t eTotal = 0.; |
Retrieve the full collection of CalDigi objects from DigiEvent. Determine how many CalDigi objects exist for this event. Fill a histogram named CALDIGICOUNT with the number of CalDigi events. Initialize some arrays used to store details. |
| TIter calDigiIter(calDigiCol); CalDigi *c = 0; while (c = (CalDigi*)calDigiIter.Next()) { // Assuming Best Range and checking only the first readout const CalXtalReadout* cRo=c->getXtalReadout(0); Float_t adcP = cRo->getAdc(CalXtalId::POS); Float_t adcN = cRo->getAdc(CalXtalId::NEG); // ligh asymmetry Float_t asy = 1.; if (adcP + adcN == 200.) asy = 1.; else asy = (adcP-adcN)/(adcP+adcN-200.); Float_t eAve = (adcP + adcN)/2.; ((TH1F*)GetObjectPtr("CALEAVE"))->Fill(eAve); ((TH1F*)GetObjectPtr("CALADC"))->Fill((float)cRo->getAdc(CalXtalId::POS)); ((TH1F*)GetObjectPtr("CALADC"))->Fill((float)cRo->getAdc(CalXtalId::NEG)); ((TH1F*)GetObjectPtr("CALRANGE"))->Fill(cRo->getRange(CalXtalId::POS)); ((TH1F*)GetObjectPtr("CALRANGE"))->Fill(cRo->getRange(CalXtalId::NEG)); // Retrieve the identifer for this crystal CalXtalId id = c->getPackedId(); Int_t layer = id.getLayer(); Int_t tower = id.getTower(); Int_t column = id.getColumn(); ((TH1F*)GetObjectPtr("CALLAYER"))->Fill(layer); ((TH1F*)GetObjectPtr("CALTOWER"))->Fill(tower); ((TH1F*)GetObjectPtr("CALCOLUMN"))->Fill(column); nLayer[layer] += 1; eLayer[layer] += eAve; eTotal += eAve; } |
Create a ROOT TIter that allows us to iterate over the collection of
CalDigis, the while loop uses the TIter to control the loop, and the
object named c, contains the CalDigi pointer. Retrieve the first crystal readout - which is assumed to be the "BEST Range" Find the ADC values for both ends: Positive and Negative. Calculate the light asymmetry. Fill a number of histograms. Determine the full CalXtalId for this CalDigi which is packed. A number of methods are available to unpack the identifier: getLayer, getTower, getColumn. And fill three more histograms with the id fields. Update the arrays: nLayer, eLayer, and eTotal based on the values we have already retrieved during this iteration of this loop. |
| ((TH1F*)GetObjectPtr("CALEAVETOTAL"))->Fill(eTotal); ((TH1F*)GetObjectPtr("CALELYR0"))->Fill(eLayer[0]); ((TH1F*)GetObjectPtr("CALELYR1"))->Fill(eLayer[1]); ((TH1F*)GetObjectPtr("CALELYR2"))->Fill(eLayer[2]); ((TH1F*)GetObjectPtr("CALELYR3"))->Fill(eLayer[3]); ((TH1F*)GetObjectPtr("CALELYR4"))->Fill(eLayer[4]); ((TH1F*)GetObjectPtr("CALELYR5"))->Fill(eLayer[5]); ((TH1F*)GetObjectPtr("CALELYR6"))->Fill(eLayer[6]); ((TH1F*)GetObjectPtr("CALELYR7"))->Fill(eLayer[7]); ((TH1F*)GetObjectPtr("CALNLYR0"))->Fill(nLayer[0]); ((TH1F*)GetObjectPtr("CALNLYR1"))->Fill(nLayer[1]); ((TH1F*)GetObjectPtr("CALNLYR2"))->Fill(nLayer[2]); ((TH1F*)GetObjectPtr("CALNLYR3"))->Fill(nLayer[3]); ((TH1F*)GetObjectPtr("CALNLYR4"))->Fill(nLayer[4]); ((TH1F*)GetObjectPtr("CALNLYR5"))->Fill(nLayer[5]); ((TH1F*)GetObjectPtr("CALNLYR6"))->Fill(nLayer[6]); ((TH1F*)GetObjectPtr("CALNLYR7"))->Fill(nLayer[7]); } |
Fill the remaining CalDigi histograms. |
| // example of filling a simple tree Float_t digiArr[2] = { (Float_t)nCalDigi, eTotal }; ((TNtuple*)GetObjectPtr("calDigiTup"))->Fill(digiArr); |
Example of filling a simple ntuple. |
If you desire to download this piece of code - here is a full copy:
void
RootTreeAnalysis::DigiCal() {
// Purpose and Method: Process
on CAL digi event
const TObjArray*
calDigiCol = evt->getCalDigiCol();
if (!calDigiCol)
return;
Int_t nCalDigi = calDigiCol->GetEntries();
((TH1F*)GetObjectPtr("CALDIGICOUNT"))->Fill((Float_t)nCalDigi);
Int_t nLayer[8]={0,0,0,0,0,0,0,0};
Float_t eLayer[8]={0.,0.,0.,0.,0.,0.,0.,0.};
Float_t eTotal = 0.;
TIter calDigiIter(calDigiCol);
CalDigi *c = 0;
while (c = (CalDigi*)calDigiIter.Next())
{
// Assuming
Best Range and checking only the first readout
const CalXtalReadout* cRo=c->getXtalReadout(0);
Float_t adcP = cRo->getAdc(CalXtalId::POS);
Float_t adcN = cRo->getAdc(CalXtalId::NEG);
// ligh
asymmetry
Float_t asy = 1.;
if
(adcP + adcN == 200.)
asy = 1.;
else
asy = (adcP-adcN)/(adcP+adcN-200.);
Float_t eAve = (adcP + adcN)/2.;
((TH1F*)GetObjectPtr("CALEAVE"))->Fill(eAve);
((TH1F*)GetObjectPtr("CALADC"))->Fill((float)cRo->getAdc(CalXtalId::POS));
((TH1F*)GetObjectPtr("CALADC"))->Fill((float)cRo->getAdc(CalXtalId::NEG));
((TH1F*)GetObjectPtr("CALRANGE"))->Fill(cRo->getRange(CalXtalId::POS));
((TH1F*)GetObjectPtr("CALRANGE"))->Fill(cRo->getRange(CalXtalId::NEG));
// Retrieve
the identifer for this crystal
CalXtalId id = c->getPackedId();
Int_t layer = id.getLayer();
Int_t tower = id.getTower();
Int_t column = id.getColumn();
((TH1F*)GetObjectPtr("CALLAYER"))->Fill(layer);
((TH1F*)GetObjectPtr("CALTOWER"))->Fill(tower);
((TH1F*)GetObjectPtr("CALCOLUMN"))->Fill(column);
nLayer[layer] += 1;
eLayer[layer] += eAve;
eTotal += eAve;
}
((TH1F*)GetObjectPtr("CALEAVETOTAL"))->Fill(eTotal);
((TH1F*)GetObjectPtr("CALELYR0"))->Fill(eLayer[0]);
((TH1F*)GetObjectPtr("CALELYR1"))->Fill(eLayer[1]);
((TH1F*)GetObjectPtr("CALELYR2"))->Fill(eLayer[2]);
((TH1F*)GetObjectPtr("CALELYR3"))->Fill(eLayer[3]);
((TH1F*)GetObjectPtr("CALELYR4"))->Fill(eLayer[4]);
((TH1F*)GetObjectPtr("CALELYR5"))->Fill(eLayer[5]);
((TH1F*)GetObjectPtr("CALELYR6"))->Fill(eLayer[6]);
((TH1F*)GetObjectPtr("CALELYR7"))->Fill(eLayer[7]);
((TH1F*)GetObjectPtr("CALNLYR0"))->Fill(nLayer[0]);
((TH1F*)GetObjectPtr("CALNLYR1"))->Fill(nLayer[1]);
((TH1F*)GetObjectPtr("CALNLYR2"))->Fill(nLayer[2]);
((TH1F*)GetObjectPtr("CALNLYR3"))->Fill(nLayer[3]);
((TH1F*)GetObjectPtr("CALNLYR4"))->Fill(nLayer[4]);
((TH1F*)GetObjectPtr("CALNLYR5"))->Fill(nLayer[5]);
((TH1F*)GetObjectPtr("CALNLYR6"))->Fill(nLayer[6]);
((TH1F*)GetObjectPtr("CALNLYR7"))->Fill(nLayer[7]);
// example of filling a simple tree
Float_t digiArr[2] = { (Float_t)nCalDigi, eTotal };
((TNtuple*)GetObjectPtr("calDigiTup"))->Fill(digiArr);
}