Question

interval_map（在icl中）库是否支持删除？我可以根据迭代器查找范围并删除范围吗？

============来自boost示例的party.cpp ===============

partyp->add( // add and element
  make_pair( 
    interval<ptime>::right_open(
      time_from_string("2008-05-20 19:30"), 
      time_from_string("2008-05-20 23:00")), 
    mary_harry));

party += // element addition can also be done via operator +=
  make_pair( 
    interval<ptime>::right_open(
      time_from_string("2008-05-20 20:10"), 
      time_from_string("2008-05-21 00:00")), 
    diana_susan);

party +=
  make_pair( 
    interval<ptime>::right_open(
      time_from_string("2008-05-20 22:15"), 
      time_from_string("2008-05-21 00:30")), 
    peter);

========== 我的问题是我可以添加删除语句，如

 party -= 
        interval<ptime>::right_open(
          time_from_string("2008-05-20 20:10"), 
          time_from_string("2008-05-21 00:00"));

我只想删除范围。任何方法都可以。

Answer 1

我知道这是一个老帖子，但我有同样的问题，我终于找到了答案。

查看docs我猜想interval_map的 Subtractability 和重叠上的聚合功能可以保证减法作为删除操作。

事实证明，传播这种添加是一个非常富有成效的概念或者减去interval_map的相关值导致间隔值对插入到interval_map中在插入的间隔值对与间隔值的冲突中已经在interval_map中的对。这个操作传播在重叠时称为聚合。

假设我必须将unix时间戳的间隔与某些记录ID（整数）进行匹配。从answer开始，我想出了这个MWE：

// interval_map_mwe.cpp #include <map> #include <set> #include <climits> #include <boost/icl/interval.hpp> #include <boost/icl/interval_map.hpp> // Set of IDs that cover a time interval typedef std::set<unsigned int> IDSet_t; // interval tree from intervals of timestamps to a set of ids typedef boost::icl::interval_map<time_t, IDSet_t> IMap_t; // a time interval typedef boost::icl::interval<time_t> Interval_t; #include <iostream> // from https://stackoverflow.com/a/22027957 inline std::ostream& operator<< (std::ostream& S, const IDSet_t& X) { S << '('; for (IDSet_t::const_iterator it = X.begin(); it != X.end(); ++it) { if (it != X.begin()) { S << ','; } S << *it; } S << ')'; return S; } int main(int argc, const char *argv[]) { (void)argc; // suppress warning (void)argv; // suppress warning IMap_t m; IDSet_t s; s.insert(1); s.insert(2); m += std::make_pair(Interval_t::right_open(100, 200), s); s = IDSet_t(); s.insert(3); s.insert(4); m += std::make_pair(Interval_t::right_open(200, 300), s); s = IDSet_t(); s.insert(5); s.insert(6); m += std::make_pair(Interval_t::right_open(150, 250), s); std::cout << "Initial map: " << std::endl; std::cout << m << std::endl; // find operation IMap_t::const_iterator it = m.find(175); std::cout << "Interval that covers 175: "; std::cout << it->first << std::endl; std::cout << "Ids in interval: " << it->second << std::endl; // partially remove 5 from interval (160,180) s = IDSet_t(); s.insert(5); m -= std::make_pair(Interval_t::right_open(160, 180), s); std::cout << "map with 5 partially removed:" << std::endl; std::cout << m << std::endl; // completelly remove 6 s = IDSet_t(); s.insert(6); // Note: maybe the range of the interval could be shorter if you can somehow obtain the minimum and maximum times m -= std::make_pair(Interval_t::right_open(0, UINT_MAX), s); std::cout << "map without 6: " << std::endl; std::cout << m << std::endl; // remove a time interval m -= Interval_t::right_open(160, 170); std::cout << "map with time span removed: " << std::endl; std::cout << m << std::endl; return 0; }

使用g ++ 4.4.7进行编译：

g++ -Wall -Wextra -std=c++98 -I /usr/include/boost148/ interval_map_mwe.cpp

我得到的输出是

Initial map: {([100,150)->{1 2 })([150,200)->{1 2 5 6 })([200,250)->{3 4 5 6 })([250,300)->{3 4 })} Interval that covers 175: [150,200) Ids in interval: (1,2,5,6) map with 5 partially removed: {([100,150)->{1 2 })([150,160)->{1 2 5 6 })([160,180)->{1 2 6 })([180,200)->{1 2 5 6 })([200,250)->{3 4 5 6 })([250,300)->{3 4 })} map without 6: {([100,150)->{1 2 })([150,160)->{1 2 5 })([160,180)->{1 2 })([180,200)->{1 2 5 })([200,250)->{3 4 5 })([250,300)->{3 4 })} map with time span removed: {([100,150)->{1 2 })([150,160)->{1 2 5 })([170,180)->{1 2 })([180,200)->{1 2 5 })([200,250)->{3 4 5 })([250,300)->{3 4 })}

注意： MWE中的数字可视为随机数。我发现用较小的数字来推理这个例子更容易。

Boost c ++库interval_map是否支持删除？

1 个答案: