pairwise {comparator}

Pairwise Similarity/Distance Matrix

Description

Computes pairwise similarities/distances between two collections of objects (strings, vectors, etc.) using the provided comparator.

Usage

pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'Comparator,ANY,missing'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'CppSeqComparator,list,list'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'CppSeqComparator,list,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'StringComparator,vector,vector'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'StringComparator,vector,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'NumericComparator,matrix,vector'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'NumericComparator,vector,matrix'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'Chebyshev,matrix,matrix'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'Chebyshev,matrix,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'Minkowski,matrix,matrix'
elementwise(comparator, x, y, ...)

## S4 method for signature 'Minkowski,matrix,matrix'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'Minkowski,matrix,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'FuzzyTokenSet,list,list'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'FuzzyTokenSet,vector,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'InVocabulary,vector,vector'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'InVocabulary,vector,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'Lookup,vector,vector'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'Lookup,vector,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'MongeElkan,list,list'
pairwise(comparator, x, y, return_matrix = FALSE, ...)

## S4 method for signature 'MongeElkan,list,'NULL''
pairwise(comparator, x, y, return_matrix = FALSE, ...)

Arguments

comparator

a comparator used to compare the objects, which is a sub-class of Comparator.

x, y

a collection of objects to compare, typically stored as entries in an atomic vector, rows in a matrix, or entries in a list. The required format depends on the type of comparator. y may be omitted or set to NULL to compare objects in x.

return_matrix

a logical of length 1. If FALSE (default), the pairwise similarities/distances will be returned as a PairwiseMatrix which is more space-efficient for symmetric comparators. If TRUE, a standard matrix is returned instead.

...

other parameters passed on to other methods.

Value

If both x and y are specified, every object in x is compared with every object in y using the comparator, and the resulting scores are returned in a size(x) by size(y) matrix.

If only x is specified, then the objects in x are compared with themselves using the comparator, and the resulting scores are returned in a size(x) by size(y) matrix.

By default, the matrix is represented as an instance of the PairwiseMatrix class, which is more space-efficient for symmetric comparators when y is not specified. However, if return_matrix = TRUE, the matrix is returned as an ordinary matrix instead.

Methods (by class)

• comparator = Comparator,x = ANY,y = missing: Compute a pairwise comparator when y

• comparator = CppSeqComparator,x = list,y = list: Specialization for CppSeqComparator where x and y are lists of sequences (vectors) to compare.

• comparator = CppSeqComparator,x = list,y = NULL: Specialization for CppSeqComparator where x is a list of sequences (vectors) to compare.

• comparator = StringComparator,x = vector,y = vector: Specialization for StringComparator where x and y are vectors of strings to compare.

• comparator = StringComparator,x = vector,y = NULL: Specialization for StringComparator where x is a vector of strings to compare.

• comparator = NumericComparator,x = matrix,y = vector: Specialization for NumericComparator where x is a matrix of rows (interpreted as vectors) to compare with a vector y.

• comparator = NumericComparator,x = vector,y = matrix: Specialization for NumericComparator where x is a vector to compare with a matrix y of rows (interpreted as vectors).

• comparator = Chebyshev,x = matrix,y = matrix: Specialization for Chebyshev where x and y matrices of rows (interpreted as vectors) to compare.

• comparator = Chebyshev,x = matrix,y = NULL: Specialization for Minkowski where x is a matrix of rows (interpreted as vectors) to compare among themselves.

• comparator = Minkowski,x = matrix,y = matrix: Specialization for a Minkowski where x and y matrices of rows (interpreted as vectors) to compare.

• comparator = Minkowski,x = matrix,y = matrix: Specialization for a Minkowski where x and y matrices of rows (interpreted as vectors) to compare.

• comparator = Minkowski,x = matrix,y = NULL: Specialization for Minkowski where x is a matrix of rows (interpreted as vectors) to compare among themselves.

• comparator = FuzzyTokenSet,x = list,y = list: Specialization for FuzzyTokenSet where x and y are lists of token vectors to compare.

• comparator = FuzzyTokenSet,x = vector,y = NULL: Specialization for FuzzyTokenSet where x is a list of token vectors to compare among themselves.

• comparator = InVocabulary,x = vector,y = vector: Specialization for InVocabulary where x and y are vectors of strings to compare.

• comparator = InVocabulary,x = vector,y = NULL: Specialization for InVocabulary where x is a vector of strings to compare among themselves.

• comparator = Lookup,x = vector,y = vector: Specialization for a Lookup where x and y are vectors of strings to compare

• comparator = Lookup,x = vector,y = NULL: Specialization for Lookup where x is a vector of strings to compare among themselves

• comparator = MongeElkan,x = list,y = list: Specialization for MongeElkan where x and y are lists of token vectors to compare.

• comparator = MongeElkan,x = list,y = NULL: Specialization for MongeElkan where x is a list of token vectors to compare among themselves.

Examples

## Computing the distances between a query point y (a 3D numeric vector) 
## and a set of reference points x
x <- rbind(c(1,0,1), c(0,0,0), c(-1,2,-1))
y <- c(10, 5, 10)
pairwise(Manhattan(), x, y)

## Computing the pairwise similarities among a set of strings
x <- c("Benjamin", "Ben", "Benny", "Bne", "Benedict", "Benson")
comparator <- DamerauLevenshtein(similarity = TRUE, normalize = TRUE)
pairwise(comparator, x, return_matrix = TRUE)  # return an ordinary matrix