operations_research::glop::Permutation< IndexType > Class Template Reference

#include <permutation.h>

Public Member Functions
	Permutation ()
	Permutation (IndexType size)
	Permutation (const Permutation &)=delete
	This type is neither copyable nor movable.
Permutation &	operator= (const Permutation &)=delete
IndexType	size () const
bool	empty () const
void	clear ()
void	resize (IndexType size, IndexType value)
void	assign (IndexType size, IndexType value)
IndexType &	operator[] (IndexType i)
IndexType	operator[] (IndexType i) const
void	PopulateFromInverse (const Permutation &inverse)
void	PopulateFromIdentity ()
	Populates the calling object with the identity permutation.
void	PopulateRandomly ()
	Populates the calling object with a random permutation.
bool	Check () const
	Returns true if the calling object contains a permutation, false otherwise.
int	ComputeSignature () const
const IndexType *	data () const
StrictITISpan< IndexType, const IndexType >	const_view () const

Detailed Description

template<typename IndexType>
class operations_research::glop::Permutation< IndexType >

Permutation<IndexType> is a template class for storing and using row- and column- permutations, when instantiated with RowIndex and ColIndex respectively.

By a row permutation we mean a permutation that maps the row 'i' of a matrix (or column vector) to the row 'permutation[i]' and in a similar fashion by a column permutation we mean a permutation that maps the column 'j' of a matrix (or row vector) to the column 'permutation[j]'.

A permutation can be represented as a matrix P, but it gets a bit tricky here: P.x permutes the rows of x according to the permutation P but x^T.P permutes the columns of x^T (a row vector) using the INVERSE permutation. That is, to permute the columns of x^T using P, one has to compute x^T.P^{-1} but P^{-1} = P^T so the notation is consistent: If P.x permutes x, then (P.x)^T = x^T.P^T permutes x^T with the same permutation.

So to be clear, if P and Q are permutation matrices, the matrix P.A.Q^{-1} is the image of A through the row permutation P and column permutation Q.

Definition at line 47 of file permutation.h.

Constructor & Destructor Documentation

Permutation() [1/3]

template<typename IndexType>

operations_research::glop::Permutation< IndexType >::Permutation ( )

inline

Definition at line 49 of file permutation.h.

Permutation() [2/3]

template<typename IndexType>

operations_research::glop::Permutation< IndexType >::Permutation ( IndexType size )

inlineexplicit

Definition at line 51 of file permutation.h.

Permutation() [3/3]

template<typename IndexType>

operations_research::glop::Permutation< IndexType >::Permutation ( const Permutation< IndexType > & )

delete

This type is neither copyable nor movable.

Member Function Documentation

assign()

template<typename IndexType>

void operations_research::glop::Permutation< IndexType >::assign ( IndexType size, IndexType value )

inline

Definition at line 66 of file permutation.h.

Check()

template<typename IndexType>

bool operations_research::glop::Permutation< IndexType >::Check

(

)

const

Returns true if the calling object contains a permutation, false otherwise.

Definition at line 177 of file permutation.h.

clear()

template<typename IndexType>

void operations_research::glop::Permutation< IndexType >::clear ( )

inline

Definition at line 60 of file permutation.h.

ComputeSignature()

template<typename IndexType>

int operations_research::glop::Permutation< IndexType >::ComputeSignature

(

)

const

Returns the signature of a permutation in O(n), where n is the permutation size. The signature of a permutation is the product of the signature of the cycles defining the permutation. The signature of an odd cycle is 1, while the signature of an even cycle is -1. (Remembering hint: the signature of a swap (a 2-cycle) is -1.)

Definition at line 195 of file permutation.h.

const_view()

template<typename IndexType>

StrictITISpan< IndexType, const IndexType > operations_research::glop::Permutation< IndexType >::const_view ( ) const

inline

Definition at line 97 of file permutation.h.

data()

template<typename IndexType>

const IndexType * operations_research::glop::Permutation< IndexType >::data ( ) const

inline

For hot-loops it might be slighlty faster to cache the pointer and avoid bound checking on each [] access.

Definition at line 95 of file permutation.h.

empty()

template<typename IndexType>

bool operations_research::glop::Permutation< IndexType >::empty ( ) const

inline

Definition at line 58 of file permutation.h.

operator=()

template<typename IndexType>

Permutation & operations_research::glop::Permutation< IndexType >::operator= ( const Permutation< IndexType > & )

delete

operator[]() [1/2]

template<typename IndexType>

IndexType & operations_research::glop::Permutation< IndexType >::operator[] ( IndexType i )

inline

Definition at line 68 of file permutation.h.

operator[]() [2/2]

template<typename IndexType>

IndexType operations_research::glop::Permutation< IndexType >::operator[] ( IndexType i ) const

inline

Definition at line 70 of file permutation.h.

PopulateFromIdentity()

template<typename IndexType>

void operations_research::glop::Permutation< IndexType >::PopulateFromIdentity

(

)

Populates the calling object with the identity permutation.

Definition at line 162 of file permutation.h.

PopulateFromInverse()

template<typename IndexType>

void operations_research::glop::Permutation< IndexType >::PopulateFromInverse

(

const Permutation< IndexType > &

inverse

)

Populates the calling object with the inverse permutation of the parameter inverse.

Implementation

Definition at line 153 of file permutation.h.

PopulateRandomly()

template<typename IndexType>

void operations_research::glop::Permutation< IndexType >::PopulateRandomly

(

)

Populates the calling object with a random permutation.

Definition at line 171 of file permutation.h.

resize()

template<typename IndexType>

void operations_research::glop::Permutation< IndexType >::resize ( IndexType size, IndexType value )

inline

Definition at line 62 of file permutation.h.

size()

template<typename IndexType>

IndexType operations_research::glop::Permutation< IndexType >::size ( ) const

inline

Definition at line 57 of file permutation.h.

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

• ortools/lp_data/permutation.h