match {arules}R Documentation

Value Matching


Provides the generic function match and the S4 methods for associations, transactions and itemMatrices. match returns a vector of the positions of (first) matches of its first argument in its second.

%in% is a more intuitive interface as a binary operator, which returns a logical vector indicating if there is a match or not for the items in the itemsets (left operand) with the items in the table (right operand).

arules defines additional binary operators for matching itemsets: %pin% uses partial matching on the table; %ain% itemsets have to match/include all items in the table; %oin% itemsets can only match/include the items in the table. The binary matching operators or often used in subset.


match(x, table, nomatch = NA_integer_, incomparables = NULL)

x %in% table
x %pin% table
x %ain% table
x %oin% table



an object of class itemMatrix, transactions or associations.


a set of associations or transactions to be matched against.


the value to be returned in the case when no match is found.


not implemented.


match: An integer vector of the same length as x giving the position in table of the first match if there is a match, otherwise nomatch.

%in%, %pin%, %ain%, %oin%: A logical vector, indicating if a match was located for each element of x.


Michael Hahsler

See Also

subset, rules-class, itemsets-class, itemMatrix-class



## get unique transactions, count frequency of unique transactions 
## and plot frequency of unique transactions
vals <- unique(Adult)
cnts <- tabulate(match(Adult, vals))
plot(sort(cnts, decreasing=TRUE))

## find all transactions which are equal to transaction 10 in Adult
which(Adult %in% Adult[10])

## for transactions we can also match directly with itemLabels.
## Find in the first 10 transactions the ones which 
## contain age=Middle-aged (see help page for class itemMatrix)
Adult[1:10] %in% "age=Middle-aged"

## find all transactions which contain items that partially match "age=" (all here).
Adult[1:10] %pin% "age="

## find all transactions that only include the item "age=Middle-aged" (none here).
Adult[1:10] %oin% "age=Middle-aged"

## find al transaction which contain both items "age=Middle-aged" and "sex=Male"
Adult[1:10] %ain% c("age=Middle-aged", "sex=Male")

[Package arules version 1.7-1 Index]