CERN ROOT：在循环问题中填写TBranches / TTree

Posted 2021-04-25

代码应该通过已创建的树进行读取，复制其分支名称，并为小于或等于0的条目记录0，为所有其他条目记录1。代码可以很好地复制分支，但是当它们用信息填充它们时，每个分支都会填充所有分支的所有信息。因此，如果一棵树有10个条目和10个分支，则第十个分支将有100个条目，第9个90，等等。下面是完整代码，填充在最后一个循环中完成。

#include <vector>
binaryTree()
{
//Creation and naming scheme
TString fileName = "binaryTree2.root";//name of file wishing to create.
TString treeName = "Binary Tree 2";//name of tree wishing to create.
TFile *file = new TFile(fileName, "RECREATE");
TTree *bTree = new TTree(treeName,"Binary Tree");

//Connection scheme
TString fileNameCopy = "hodoscopehittree7.root";//name of file you will be accessing.
TString treeNameCopy = "tree";//Name of tree within file you are accessing.
TFile *filePtr = new TFile(fileNameCopy);//points to file with previously created tree
TTree *treePtr = (TTree *) filePtr->Get(treeNameCopy);//Ptr to tree within accessed file.
TObjArray *obj = treePtr->GetListOfBranches();//Ptr to branches.
int branchNum = obj->GetEntries();//Number of branches in accessed tree.

//Vector to hold all of the information from the tree.  
vector<vector<int>> dataHolder;

int* inHist;//Ptr to become the entry.
int inVal;
vector <int> entryVec;//Vector of ints that the branches will rely on.
entryVec.resize(branchNum);
TString branchName;
const int entryNum = treePtr->GetEntries();//Number of entries in each branch.

//This loop creates a branch in the binary tree with the same name as the 
//branch in the tree being accessed and fills the dataHolder vector with 
//vectors.
for (int i = 0; i < branchNum; i++)
{
  TString temp;
  temp = "entryVec[";
  temp += (i);
  temp += "]/I";
  branchName = obj -> At(i)-> GetName();
  bTree -> Branch(branchName, &entryVec[i],temp);
  vector <int> tempVec;
  dataHolder.push_back(tempVec); 
}

//This loop reads the entries of each branch within the accessed tree. If the 
//value is less than or equal to zero, 0 is added to the dataHolder and  if 
//not 1 is added to the dataHolder.
for (int i = 0; i < branchNum; i++)
{
    branchName = obj-> At(i)-> GetName(); //Gets name of branch at index i
    treePtr -> SetBranchAddress(branchName, &inHist);

    for (int j = 0; j < entryNum; j++)
    {
      treePtr -> GetEntry(j);
      inVal = inHist;

      if (inVal <= 0)
      {
        dataHolder[i].push_back(0);
      }

      else
      {
        dataHolder[i].push_back(1);
      }
   }

}

//This loop fills the tree. Each inner loop reads the jth element of the 
//datHolder and inputs that information int the entryVec. The outer loop fills 
//the tree and then loops over all of the entries. 
for (int i = 0; i < entryNum; i++)
{
  for (int j = 0; j < branchNum; j++)
  {
    entryVec[j] = dataHolder[j][i];
  }  
  bTree -> Fill();
}

file -> Write();
cout << "Your program has finished; " << treeName << " has been created."; 
cout << endl;
filePtr-> Close();
new TBrowser();
}

答案

解决方案由我合作的其他人解决。分支创建临时的最后一部分应该是branchName / I，所以当更改为：

temp = branchName; temp + =“/ I”;

代码完美无缺。