nomclust (version 2.6.2)

of: Occurence Frequency (OF) Measure

Description

The function calculates a dissimilarity matrix based on the OF similarity measure.

Usage

of(data, var.weights = NULL)

Value

The function returns an object of the class "dist".

Arguments

data

A data.frame or a matrix with cases in rows and variables in columns.

var.weights

A numeric vector setting weights to the used variables. One can choose the real numbers from zero to one.

Author

Zdenek Sulc.
Contact:

Details

The OF (Occurrence Frequency) measure was originally constructed for the text mining tasks, see (Sparck-Jones, 1972), later, it was adjusted for categorical variables, see (Boriah et al., 2008) It assigns higher weight to mismatches on less frequent values and otherwise.

References

Boriah S., Chandola V., Kumar V. (2008). Similarity measures for categorical data: A comparative evaluation. In: Proceedings of the 8th SIAM International Conference on Data Mining, SIAM, p. 243-254.

Spark-Jones K. (1972). A statistical interpretation of term specificity and its application in retrieval. In Journal of Documentation, 28(1), p. 11-21. Later: Journal of Documentation, 60(5) (2002), p. 493-502.

See Also

anderberg, burnaby, eskin, gambaryan, good1, goodall1, good2, goodall2, good3, goodall3, good4, goodall4, iof, lin, lin1, sm, smirnov, ve, vm.

Examples

# sample data
data(data20)

# dissimilarity matrix calculation
prox.of <- of(data20)

# dissimilarity matrix calculation with variable weights
weights.of <- of(data20, var.weights = c(0.7, 1, 0.9, 0.5, 0))