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c++ - Root - failed filling branch : memory-resident tree

问题描述

I am trying to merge trees doing :

string filename_;
TList *list = new TList;

///Loop on all .root output files
for (int i = 1; i < 13; ++i) {
  string filename_ = "file_";
  string file_extension = ".root";
  stringstream ss;
  ss << i;
  string str = ss.str();
  filename_ = filename_+str+file_extension;
  const char* c_filename = filename_.c_str();
  TFile *file_adress = TFile::Open(c_filename);
  TTree *tree_adress = (TTree*)file_adress->Get("pulses");
  list->Add(tree_adress);
}

// Output tree:
TTree *TPulses = TTree::MergeTrees(list);

But I am getting this error, which is quietly explicite :

Error in <TTree::Fill>: Failed filling branch:pulses.pulse_time, nbytes=-1, entry=115710
 This error is symptomatic of a Tree created as a memory-resident Tree
 Instead of doing:
    TTree *T = new TTree(...)
    TFile *f = new TFile(...)
 you should do:
    TFile *f = new TFile(...)
    TTree *T = new TTree(...)

But I am creating the TFile before the TTree in the for loop, so I don't understand. Does someone have an idea ?

标签： c++root-framework

解决方案

您看到的错误消息来自TTree您正在写入的内容。据我了解您的代码，TFile *file_adressandTTree *tree_adress被打开以供阅读，而您写入TTree *TPulses. 我没有看到TFile::Open（如果它是READ用于只读或update用于操作内容）的默认设置，但从您的输出中我声称TPulses不会在您打开的最后一个文件中创建，而是在 RAM 中创建并且您用完了（请参阅文档）。一个常见的模式是在创建之前创建一个输出文件TPulses：

TFile* outputfile = TFile::Open("output.root", "recreate");
TTree* TPulses = TTree::MergeTrees(list);
// ...
TPulses->Write();
outputfile->Close();
delete outputfile;

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