honey::Permute_< Real > Class Template Reference

Generate all permutations of a list. A functor can be specified for fast culling of entire subtrees of undesired permutations. More...

#include <Permute.h>

Classes
class	Iter
	Iter for permutations of a list. More...

Static Public Member Functions
template<class T >
static Range_< Iter< T >, Iter< T > >	range (const vector< T > &list, const typename Iter< T >::Func &func=nullptr)
	Create a permutation range. More...

Detailed Description

template<class Real>
class honey::Permute_< Real >

Generate all permutations of a list. A functor can be specified for fast culling of entire subtrees of undesired permutations.

The permuations are in lexicographic order. ie. {1,2,3} , {1,3,2} , {2,1,3} , {2,3,1} , {3,1,2} , {3,2,1}
The current permutation list can be accessed with the dereference/pointer operators.

If a functor is provided then undesired subtrees can be culled. For example, skip all permutations that start with {0,1}:

Permute::range(list, [](const vector<const Real*>& perm) { return !(perm.size() == 2 && *perm[0] == 0 && *perm[1] == 1); });

When an iter is stepped (++), its functor will be called before traversing each permutation subtree.
For example, perm will first contain {1}, if the functor returns true then the next test is {1,2}, then finally {1,2,3}.
When the functor returns true for a full permutation (ex. {1,2,3}), then the iter step is complete.

Copies of the iter share its permutation state, so a change to one iter affects all others.

Algorithm from: "Lexicographic Permutations with Restricted Prefixes" from The Art of Computer Programming, Vol 4, Section 7.2.1.2

Member Function Documentation

template<class Real >

template<class T >

static Range_<Iter<T>, Iter<T> > honey::Permute_< Real >::range ( const vector< T > &  list, const typename Iter< T >::Func &  func = nullptr  )

inlinestatic

Create a permutation range.

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

• src/common/Honey/Math/Random/Permute.h