找到两个字符串向量的交集

Question

我有两个字符串向量,并希望找到两者中存在的字符串,用公共元素填充第三个向量.编辑:我已经添加了完整的代码清单与相应的输出,以便事情清楚.

  std::cout << "size " << m_HLTMap->size() << std::endl;

  /// Vector to store the wanted, present and found triggers
  std::vector<std::string> wantedTriggers;
  wantedTriggers.push_back("L2_xe25");
  wantedTriggers.push_back("L2_vtxbeamspot_FSTracks_L2Star_A");
  std::vector<std::string> allTriggers;

  // Push all the trigger names to a vector
  std::map<std::string, int>::iterator itr = m_HLTMap->begin();
  std::map<std::string, int>::iterator itrLast = m_HLTMap->end();
  for(;itr!=itrLast;++itr)
  {
    allTriggers.push_back((*itr).first);
  }; // End itr

  /// Sort the list of trigger names and find the intersection
  /// Build a typdef to make things clearer
  std::vector<std::string>::iterator wFirst = wantedTriggers.begin();
  std::vector<std::string>::iterator wLast = wantedTriggers.end();
  std::vector<std::string>::iterator aFirst = allTriggers.begin();
  std::vector<std::string>::iterator aLast = allTriggers.end();

  std::vector<std::string> foundTriggers;

  for(;aFirst!=aLast;++aFirst)
  {
    std::cout << "Found:" << (*aFirst) << std::endl; 
  };

  std::vector<std::string>::iterator it;

  std::sort(wFirst, wLast);
  std::sort(aFirst, aLast);
  std::set_intersection(wFirst, wLast, aFirst, aLast, back_inserter(foundTriggers));

  std::cout << "Found this many triggers: " << foundTriggers.size() << std::endl;
  for(it=foundTriggers.begin();it!=foundTriggers.end();++it)
  {
    std::cout << "Found in both" << (*it) << std::endl;
  }; // End for intersection

然后输出

这是部分输出,向量中有超过1000个元素,所以我没有包含完整输出:

Found:L2_te1400
Found:L2_te1600
Found:L2_te600
Found:L2_trk16_Central_Tau_IDCalib
Found:L2_trk16_Fwd_Tau_IDCalib
Found:L2_trk29_Central_Tau_IDCalib
Found:L2_trk29_Fwd_Tau_IDCalib
Found:L2_trk9_Central_Tau_IDCalib
Found:L2_trk9_Fwd_Tau_IDCalib
Found:L2_vtxbeamspot_FSTracks_L2Star_A
Found:L2_vtxbeamspot_FSTracks_L2Star_B
Found:L2_vtxbeamspot_activeTE_L2Star_A_peb
Found:L2_vtxbeamspot_activeTE_L2Star_B_peb
Found:L2_vtxbeamspot_allTE_L2Star_A_peb
Found:L2_vtxbeamspot_allTE_L2Star_B_peb
Found:L2_xe25
Found:L2_xe35
Found:L2_xe40
Found:L2_xe45
Found:L2_xe45T
Found:L2_xe55
Found:L2_xe55T
Found:L2_xe55_LArNoiseBurst
Found:L2_xe65
Found:L2_xe65_tight
Found:L2_xe75
Found:L2_xe90
Found:L2_xe90_tight
Found:L2_xe_NoCut_allL1
Found:L2_xs15
Found:L2_xs30
Found:L2_xs45
Found:L2_xs50
Found:L2_xs60
Found:L2_xs65
Found:L2_zerobias_NoAlg
Found:L2_zerobias_Overlay_NoAlg
Found this many triggers: 0

可能的原因

我开始认为我编译代码的方式是责备.我目前正在使用ROOT(物理数据分析框架)进行编译,而不是进行独立编译.我觉得它与STL算法库不能很好地工作,这就是问题的原因,特别是考虑到有多少人似乎有代码为他们工作.我将尝试进行独立编译并重新运行.

Answer 1

传递foundTriggers.begin(),为foundTriggers空,作为输出参数不会导致输出被推送到foundTriggers.相反,它会将迭代器递增超过向量的末尾而不调整大小,随机破坏内存.

您想使用插入迭代器:

std::set_intersection(wFirst, wLast, aFirst, aLast, 
    std::back_inserter(foundTriggers));

更新:正如评论中指出的那样,向量的大小至少要足够大,以便结果,所以你的代码应该工作.请注意,您应该使用返回的迭代器set_intersection来指示交集的结尾 - 您的代码会忽略它,因此您还将迭代输出结尾处留下的空字符串.

您可以发布一个完整的测试用例,以便我们可以看到交叉点是否实际为空？