affinity: Computing Affinity Between Items

Description Usage Arguments Details Value Author(s) References See Also Examples

Description

Provides the generic function affinity and the S4 methods to compute and return a similarity matrix with the affinities between items for a set of transactions.

Usage

1

Arguments

x

a matrix or an object of class itemMatrix or transactions.

Details

Affinity between the two items i and j is defined by Aggarwal et al. (2002) as

A(i,j) = sup({i,j})/(sup({i}) + sup({j}) - sup({i,j})),

where sup(.) is the support measure. This means that affinity is the Jaccard similarity between items.

Value

returns an object of class ar_similarity which represents the affinities between items in x.

Author(s)

Michael Hahsler

References

Charu C. Aggarwal, Cecilia Procopiuc, and Philip S. Yu (2002) Finding localized associations in market basket data, IEEE Trans. on Knowledge and Data Engineering, 14(1):51–62.

See Also

dissimilarity, ar_similarity-class, itemMatrix-class

Examples

1
2
3
4
5
6
7
8
data("Adult")

## choose a sample, calculate affinities 
s <- sample(Adult, 500)
s

a <- affinity(s)
image(a)

Example output

Loading required package: Matrix

Attaching package: 'arules'

The following objects are masked from 'package:base':

    abbreviate, write

transactions in sparse format with
 500 transactions (rows) and
 115 items (columns)

arules documentation built on Aug. 29, 2019, 9:03 a.m.