addComplement {arules}

Add Complement-items to Transactions

Description

Provides the generic function addComplement() and a method for transactions to add complement items. That is, it adds an artificial item to each transaction which does not contain the original item. Such items are also called negative items (Antonie et al, 2014).

Usage

addComplement(x, labels, complementLabels = NULL)

## S4 method for signature 'transactions'
addComplement(x, labels, complementLabels = NULL)

Arguments

x

an object of class transactions.

labels

character strings; item labels for which complements should be created.

complementLabels

character strings; labels for the artificial complement-items. If omitted then the original label is prepended by "!" to form the complement-item label.

Value

Returns an object of class transactions with complement items added.

Author(s)

Michael Hahsler

References

Antonie L., Li J., Zaiane O. (2014) Negative Association Rules. In: Aggarwal C., Han J. (eds) Frequent Pattern Mining, Springer International Publishing, pp. 135-145. doi:10.1007/978-3-319-07821-2_6

Examples

data("Groceries")

## add a complement-items for "whole milk" and "other vegetables"
g2 <- addComplement(Groceries, c("whole milk", "other vegetables"))
g2
tail(itemInfo(g2))
inspect(head(g2, 3))

## use a custom label for the complement-item
g3 <- addComplement(g2, "coffee", complementLabels = "NO coffee")
inspect(head(g2, 3))

## add complements for all items (this is excessive for this dataset)
g4 <- addComplement(Groceries, itemLabels(Groceries))
g4

## add complements for all items with a minimum support of 0.1
g5 <- addComplement(Groceries, names(which(itemFrequency(Groceries) >= 0.1)))
g5