CombinationsGenerator Class Reference

Collaboration diagram for CombinationsGenerator:

Public Member Functions
	CombinationsGenerator (std::size_t n, std::size_t k)
std::vector< std::size_t >	get () const
bool	bump ()

Private Attributes
bool	m_invalid
std::string	m_bitmask
std::size_t	m_N
std::size_t	m_K
std::vector< std::size_t >	m_NequalsKvec

Friends
std::ostream &	operator<< (std::ostream &, const CombinationsGenerator &)

Detailed Description

generate all possible combinations of objects

Warning

The class is not making any assumption as if the this are combinations with objets repeated, i.e. it works on set of indices.

Constructor & Destructor Documentation

CombinationsGenerator()

CombinationsGenerator::CombinationsGenerator ( std::size_t  n, std::size_t  k  )

inline

Definition at line 29 of file CombinationsGenerator.h.

                                                 :
    m_invalid{false}, m_N{n}, m_K(k){
 
    // if n==k, std::prev_permutations never returns false,
    // so treat as a special case
    if (m_N == 0 or m_K > m_N) {
      m_invalid = true;
    } else if (m_N==m_K) {
      m_NequalsKvec.reserve(m_K);
      for(std::size_t i = 0u; i != m_K; ++i){
    m_NequalsKvec.push_back(i);
      }
    } else if (m_K < m_N){
      m_bitmask = std::string(m_K, 1);
      m_bitmask.resize(m_N, 0);
    } else {
      m_invalid = true;
    }
  }

Member Function Documentation

bump()

bool CombinationsGenerator::bump ( )

inline

Definition at line 65 of file CombinationsGenerator.h.

              {
    // returns true if have cycled
 
    if (m_K < m_N and m_K > 0) {
      return  ! std::prev_permutation(m_bitmask.begin(), m_bitmask.end());
    }
    return true;
  }

get()

std::vector<std::size_t> CombinationsGenerator::get ( ) const

inline

Definition at line 50 of file CombinationsGenerator.h.

                                   {
 
    if (m_K < m_N and m_K > 0) {
      std::vector<std::size_t> comb;
      for(std::size_t  i = 0; i < m_bitmask.size(); ++i){
    if(m_bitmask[i]){comb.push_back(i);}
      }
      return comb;
    }
    
    if(m_K == m_N) {return m_NequalsKvec;}
 
    return std::vector<std::size_t>();
  }

Friends And Related Function Documentation

operator<<

std::ostream& operator<< ( std::ostream &  , const CombinationsGenerator &    )

friend

Definition at line 7 of file CombinationsGenerator.cxx.

                                                                         {
  os << "CombinationsGenerator m_invalid " <<std::boolalpha << cg.m_invalid
     << " bitmask len " << cg.m_bitmask.size() 
       << " m_bitmask: ";
  for (const auto& c : cg.m_bitmask) {
    if (c == 0) {
      os << 0 << " ";
    } else if (c == 1) {
      os << 1 << " ";
    } else {
      os << '?' << " ";
    }
  }
  os << " m_N " << cg.m_N << " m_K " << cg.m_K;
 
  os << '\n';
  return os;
}

Member Data Documentation

m_bitmask

std::string CombinationsGenerator::m_bitmask

private

Definition at line 77 of file CombinationsGenerator.h.

m_invalid

bool CombinationsGenerator::m_invalid

private

Definition at line 76 of file CombinationsGenerator.h.

m_K

std::size_t CombinationsGenerator::m_K

private

Definition at line 80 of file CombinationsGenerator.h.

m_N

std::size_t CombinationsGenerator::m_N

private

Definition at line 79 of file CombinationsGenerator.h.

m_NequalsKvec

std::vector<std::size_t> CombinationsGenerator::m_NequalsKvec

private

Definition at line 81 of file CombinationsGenerator.h.

---

The documentation for this class was generated from the following files:

• TrigCompositeUtils/TrigCompositeUtils/Combinators.h
• CombinationsGenerator.h