Jaccard Class Reference

Class for storing and computing the Jaccard index (Tanimoto coefficient) More...

Inheritance diagram for Jaccard:

List of all members.

Public Member Functions
void	AddEntity (int entity_id)
	Add an entity to the CorrelationMatrix by growing it to the requested size.
override void	ComputeCorrelations (IBooleanMatrix entity_data)
	Compute the correlations from an implicit feedback, positive-only dataset.
IMatrix< T >	CreateMatrix (int num_rows, int num_columns)
	Create a matrix with a given number of rows and columns.
int[]	GetNearestNeighbors (int entity_id, uint k)
	Get the k nearest neighbors of a given entity.
IList< int >	GetPositivelyCorrelatedEntities (int entity_id)
	Get all entities that are positively correlated to an entity, sorted by correlation.
void	Grow (int num_rows, int num_columns)
	Grows the matrix to the requested size, if necessary.
	Jaccard (int num_entities)
	Creates an object of type Jaccard.
double	SumUp (int entity_id, ICollection< int > entities)
	Sum up the correlations between a given entity and the entities in a collection.
	SymmetricMatrix (int dim)
	Initializes a new instance of the SymmetricMatrix class.
IMatrix< T >	Transpose ()
	Get the transpose of the matrix, i.e. a matrix where rows and columns are interchanged.
void	Write (StreamWriter writer)
	Write out the correlations to a StreamWriter.
Static Public Member Functions
static float	ComputeCorrelation (HashSet< int > vector_i, HashSet< int > vector_j)
	Computes the Jaccard index of two binary vectors.
static CorrelationMatrix	Create (IBooleanMatrix vectors)
	Creates a Jaccard index matrix from given data.
static CorrelationMatrix	Create (int num_entities)
	Creates a correlation matrix.
static CorrelationMatrix	ReadCorrelationMatrix (StreamReader reader)
	Creates a CorrelationMatrix from the lines of a StreamReader.
Public Attributes
int	dim
	Dimension, the number of rows and columns.
Protected Attributes
internal T[][]	data
	Data array: data is stored in columns.
int	num_entities
	Number of entities, e.g. users or items.
Properties
override bool	IsSymmetric [get]
	returns true if the matrix is symmetric, which is generally the case for similarity matrices
int	NumberOfColumns [get]
	The number of columns of the matrix.
int	NumberOfRows [get]
	The number of rows of the matrix.
virtual T	this[int i, int j] [get, set]
T	this[int x, int y] [get, set]
	The value at (i,j)

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Detailed Description

Class for storing and computing the Jaccard index (Tanimoto coefficient)

The Jaccard index is often also called the Tanimiti coefficient.

http://en.wikipedia.org/wiki/Jaccard_index

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Constructor & Destructor Documentation

Jaccard

(

int

num_entities

)

[inline]

Creates an object of type Jaccard.

Parameters:

num_entities

the number of entities

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Member Function Documentation

void AddEntity

(

int

entity_id

)

[inline, inherited]

Add an entity to the CorrelationMatrix by growing it to the requested size.

Note that you still have to correctly compute and set the entity's correlation values

Parameters:

entity_id

the numerical ID of the entity

static float ComputeCorrelation	(	HashSet< int >	vector_i,
		HashSet< int >	vector_j
	)		[inline, static]

Computes the Jaccard index of two binary vectors.

Parameters:

vector_i	the first vector
vector_j	the second vector

Returns:

the cosine similarity between the two vectors

override void ComputeCorrelations

(

IBooleanMatrix

entity_data

)

[inline, virtual]

Compute the correlations from an implicit feedback, positive-only dataset.

Parameters:

entity_data

the implicit feedback set, rows contain the entities to correlate

Implements BinaryDataCorrelationMatrix.

static CorrelationMatrix Create

(

IBooleanMatrix

vectors

)

[inline, static]

Creates a Jaccard index matrix from given data.

Parameters:

vectors

the boolean data

Returns:

the similarity matrix based on the data

static CorrelationMatrix Create

(

int

num_entities

)

[inline, static, inherited]

Creates a correlation matrix.

Gives out a useful warning if there is not enough memory

Parameters:

num_entities

the number of entities

Returns:

the correlation matrix

IMatrix<T> CreateMatrix	(	int	num_rows,
		int	num_columns
	)		[inline, inherited]

Create a matrix with a given number of rows and columns.

Parameters:

num_rows	the number of rows
num_columns	the number of columns

Returns:

A matrix with num_rows rows and num_column columns

Implements IMatrix< T >.

int [] GetNearestNeighbors	(	int	entity_id,
		uint	k
	)		[inline, inherited]

Get the k nearest neighbors of a given entity.

Parameters:

entity_id	the numerical ID of the entity
k	the neighborhood size

Returns:

an array containing the numerical IDs of the k nearest neighbors

IList<int> GetPositivelyCorrelatedEntities

(

int

entity_id

)

[inline, inherited]

Get all entities that are positively correlated to an entity, sorted by correlation.

Parameters:

entity_id

the entity ID

Returns:

a sorted list of all entities that are positively correlated to entitiy_id

void Grow	(	int	num_rows,
		int	num_cols
	)		[inline, inherited]

Grows the matrix to the requested size, if necessary.

The new entries are filled with zeros.

Parameters:

num_rows	the minimum number of rows
num_cols	the minimum number of columns

Implements IMatrix< T >.

static CorrelationMatrix ReadCorrelationMatrix

(

StreamReader

reader

)

[inline, static, inherited]

Creates a CorrelationMatrix from the lines of a StreamReader.

In the first line, we expect to be the number of entities. All the other lines have the format

		      EntityID1 EntityID2 Correlation
		    

where EntityID1 and EntityID2 are non-negative integers and Correlation is a floating point number.

Parameters:

reader

the StreamReader to read from

double SumUp	(	int	entity_id,
		ICollection< int >	entities
	)		[inline, inherited]

Sum up the correlations between a given entity and the entities in a collection.

Parameters:

entity_id	the numerical ID of the entity
entities	a collection containing the numerical IDs of the entities to compare to

Returns:

the correlation sum

SymmetricMatrix

(

int

dim

)

[inline, inherited]

Initializes a new instance of the SymmetricMatrix class.

Parameters:

dim	the number of rows and columns

IMatrix<T> Transpose

(

)

[inline, inherited]

Get the transpose of the matrix, i.e. a matrix where rows and columns are interchanged.

Returns:

the transpose of the matrix (copy)

Implements IMatrix< T >.

void Write

(

StreamWriter

writer

)

[inline, inherited]

Write out the correlations to a StreamWriter.

Parameters:

writer

A StreamWriter

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Member Data Documentation

internal T [][] data [protected, inherited]

Data array: data is stored in columns.

int dim [inherited]

Dimension, the number of rows and columns.

int num_entities [protected, inherited]

Number of entities, e.g. users or items.

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Property Documentation

int NumberOfColumns [get, inherited]

The number of columns of the matrix.

The number of columns of the matrix

Implements IMatrix< T >.

int NumberOfRows [get, inherited]

The number of rows of the matrix.

The number of rows of the matrix

Implements IMatrix< T >.

T this[int x, int y] [get, set, inherited]

The value at (i,j)

The value at (i,j)

Parameters:

x	the row ID
y	the column ID

Implemented in SparseMatrix< T >, SkewSymmetricSparseMatrix, SymmetricSparseMatrix< T >, SparseBooleanMatrix, SparseBooleanMatrixBinarySearch, and SparseBooleanMatrixStatic.

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

• Jaccard.cs