Provides the generic function affinity() and methods to compute
and return a similarity matrix with the affinities between items for a set
itemsets stored in a matrix or in transactions via its superclass itemMatrix.
Usage
affinity(x)
# S4 method for matrix
affinity(x)
# S4 method for itemMatrix
affinity(x)
Value
returns an object of class ar_similarity which represents the
affinities between items in x.
Arguments
x
a matrix or an object of class itemMatrix or
transactions containing itemsets.
Author
Michael Hahsler
Details
Affinity between the two items \(i\) and \(j\) is defined by Aggarwal et
al. (2002) as $$A(i,j) = \frac{supp(\{i,j\})}{supp(\{i\}) + supp(\{j\}) -
supp(\{i,j\})},$$
where \(supp(.)\) is the support measure. Note that affinity is equivalent to the
Jaccard similarity between items.
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
Other proximity classes and functions:
dissimilarity(),
predict(),
proximity-classes