ppforest2::utils Namespace Reference

Utility functions for std::map manipulation. More...

Functions
template<typename K, typename V>
std::map< V, std::set< K > >	invert (std::map< K, V > const &map)
	Invert a map: values become keys, original keys are grouped into sets.
template<typename K, typename V>
std::set< K >	keys (std::map< K, V > const &map)
	Extract all keys from a map as a set.
template<typename Size>
std::vector< int >	range_vector (Size n)
	Build the sequence [0, 1, ..., n - 1] as std::vector<int>.
template<typename K, typename V>
std::set< V >	values (std::map< K, V > const &map)
	Extract all values from a map as a set.

Detailed Description

Utility functions for std::map manipulation.

Function Documentation

invert()

template<typename K, typename V>

std::map< V, std::set< K > > ppforest2::utils::invert

(

std::map< K, V > const &

map

)

Invert a map: values become keys, original keys are grouped into sets.

Parameters

map	Input map {K → V}.

Returns

Inverted map {V → set<K>}.

keys()

template<typename K, typename V>

std::set< K > ppforest2::utils::keys

(

std::map< K, V > const &

map

)

Extract all keys from a map as a set.

Parameters

map	Input map.

Returns

Set of all keys.

range_vector()

template<typename Size>

std::vector< int > ppforest2::utils::range_vector ( Size n )

inline

Build the sequence [0, 1, ..., n - 1] as std::vector<int>.

Replaces the pattern

std::vector<int> v(n);
std::iota(v.begin(), v.end(), 0);

which appears anywhere we need a permutation buffer or a "select all rows/columns" index list. int is the right element type for every caller in the codebase: Eigen's indexed assignment, Eigen column selection, and the strategy Result types all consume int indices.

Template Parameters

Size	Any integral type (e.g. int, std::size_t, Eigen::Index). Cast to std::size_t for the std::vector constructor.

Parameters

n	Length of the resulting sequence (must be >= 0).

values()

template<typename K, typename V>

std::set< V > ppforest2::utils::values

(

std::map< K, V > const &

map

)

Extract all values from a map as a set.

Parameters

map	Input map.

Returns

Set of all values (duplicates collapsed).