arules: tidLists-class – R documentation

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tidLists-class

Class tidLists — Transaction ID Lists for Items/Itemsets

Description

Transaction ID lists contains a set of lists. Each list is associated with an item/itemset and stores the IDs of the transactions which support the item/itemset. tidLists uses the class ngCMatrix to efficiently store the transaction ID lists as a sparse matrix. Each column in the matrix represents one transaction ID list.

tidLists can be used for different purposes. For some operations (e.g., support counting) it is efficient to coerce a transactions database into tidLists where each list contains the transaction IDs for an item (and the support is given by the length of the list).

The implementation of the Eclat mining algorithm (which uses transaction ID list intersection) can also produce transaction ID lists for the found itemsets as part of the returned itemsets object. These lists can then be used for further computation.

Objects from the Class

Objects are created by Eclat if the eclat function is called with tidLists = TRUE in the ECparameter object, and returned as part of the mined itemsets. Objects can also be created by coercion from an object of class transactions or by calls of the form new("tidLists", ...).

Slots

data:: object of class ngCMatrix.
itemInfo:: a data.frame to store item/itemset labels (see itemMatrix class).
transactionInfo:: a data.frame with vectors of the same length as the number of transactions. Each vector can hold additional information e.g., store transaction IDs or user IDs for each transaction.

Methods

coerce: signature(from = "tidLists", to = "ngCMatrix"); access the sparse matrix representation. In the ngCMatrix each column represents the transaction IDs for one item/itemset.
coerce: signature(from = "tidLists", to = "list")
coerce: signature(from = "list", to = "tidLists")
coerce: signature(from = "tidLists", to = "matrix")
coerce: signature(from = "tidLists", to = "itemMatrix")
coerce: signature(from = "tidLists", to = "transactions")
coerce: signature(from = "itemMatrix", to = "tidLists"); this also coerces from transactions.
coerce: signature(from = "transactions", to = "tidLists")
c: signature(x = "tidLists"); combine.
dim: signature(x = "tidLists"); returns the dimensions of the sparse Matrix representing the tidLists.
dimnames, rownames, colnames: signature(x = "transactions"); returns row (items/itemsets) and column (transactionIDs if available) names.
labels: signature(x = "transactions"); returns the labels for the itemsets in each transaction (see itemMatrix).
inspect: inspect the transaction ID lists.
itemInfo: returns the slot itemInfo.
itemLabels: signature(object = "tidLists"); returns the item labels as a character vector.
labels: signature(x = "transactions"); returns the labels (transaction IDs).
show: signature(object = "tidLists")
summary: signature(object = "tidLists")
transactionInfo: signature(x = "transactions"): returns the slot transactionInfo.

Author(s)

Michael Hahsler

Examples

## Create transaction data set.
data <- list(
  c("a","b","c"),
  c("a","b"),
  c("a","b","d"),
  c("b","e"),
  c("b","c","e"),
  c("a","d","e"),
  c("a","c"),
  c("a","b","d"),
  c("c","e"),
  c("a","b","d","e")
  )
data <- as(data, "transactions")
data

## convert transactions to transaction ID lists
tl <- as(data, "tidLists")
tl 

inspect(tl)
dim(tl)
dimnames(tl)

## inspect visually
image(tl)

## mine itemsets with transaction ID lists
f <- eclat(data, parameter = list(support = 0, tidLists = TRUE))
tl2 <- tidLists(f)
inspect(tl2)

arules

Mining Association Rules and Frequent Itemsets

v1.6-7

GPL-3

Authors

Michael Hahsler [aut, cre, cph], Christian Buchta [aut, cph], Bettina Gruen [aut, cph], Kurt Hornik [aut, cph], Ian Johnson [ctb, cph], Christian Borgelt [ctb, cph]

Initial release

2021-03-12