# affinity

0th

Percentile

##### Computing Affinity Between Items

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.

Keywords
models, cluster
##### Usage
affinity(x)
##### 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 $$A(i,j) = \frac{sup(\{i,j\})}{sup(\{i\}) + sup(\{j\}) - sup(\{i,j\})},$$ 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.

##### 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.

dissimilarity, ar_similarity-class, itemMatrix-class

##### Aliases
• affinity
• affinity,itemMatrix-method
• affinity,matrix-method
##### Examples
# NOT RUN {

## choose a sample, calculate affinities