Access to TMap and TClonesArray IO

{
//  root macro to access TMap from file                  6/98 RXD

      printf(" starting TMap access n");


  gROOT->Reset();


// access root file and set up tree.

   TFile f("Event.root");
 
   TTree *T = (TTree*)f.Get("T");

// create pointer to to-be-read-in TMap and init to zero.  

   TMap* readMap = 0;

// set up the branch for the map and tell it where the TMap really is
 
   TBranch *testMap = T->GetBranch("testMap");
   testMap->SetAddress(&readMap);

   TClonesArray* readClone = 0;

   TBranch *testClone = T->GetBranch("testClone");
   testClone->SetAddress(&readClone);


// the objects stored in the TMap

   aKey* key;
   aVal* val;

   Int_t nevent = T->GetEntries();

   printf(" read in file for %i events n",nevent);


   for (Int_t i=0;i<nevent;i++) {

     // get the whole event

     T->GetEvent(i);


      // set up the TMap iterator

     TMapIter next(readMap);

     printf(" loop over map elements n");

     while (key = (aKey*)next()) {
       val = (aVal*)readMap->GetValue(key);
       printf("key %i  val %f type %i n",key->GetKey(),val->GetVal(),
	 val->GetMcPart()->GetType());
     }  

     TClonesArray& mcpart = *readClone;

     for (Int_t i=0; i<4; ++i) {
       printf("Particle type %i n",((McPart*)mcpart[i])->GetType());
     } 


   }


}