affinity | R Documentation |

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.

affinity(x) ## S4 method for signature 'matrix' affinity(x) ## S4 method for signature 'itemMatrix' affinity(x)

`x` |
a matrix or an object of class itemMatrix or transactions containing itemsets. |

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

*A(i,j) = 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.

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

.

Michael Hahsler

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.

Other proximity classes and functions:
`dissimilarity()`

,
`predict()`

,
`proximity-classes`

data("Adult") ## choose a sample, calculate affinities s <- sample(Adult, 500) s a <- affinity(s) image(a)

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