Class “transactions” - Binary Incidence Matrix for Transactions

Description

The transactions class represents transaction data used for mining itemsets or rules. It is a direct extension of class itemMatrix to store a binary incidence matrix, item labels, and optionally transaction IDs and user IDs.

Objects from the Class

Objects are created by coercion from objects of other classes or by calls of the form new("transactions", ...).

Slots

transactionInfo:

object of class "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.

data:

object of class dgCMatrix to store the binary incidence matrix (see itemMatrix class)

itemInfo:

object of class "data.frame" to store item labels (see itemMatrix class)

Extends

Class itemMatrix, directly.

Methods

[

signature(x = "transactions"); extracts a subset from the incidence matrix. The first argument extracts transactions and the second argument can be used to extract a subset of items (using item IDs)

coerce

signature(from = "matrix", to = "transactions"); produces a transactions data set from a binary incidence matrix. The row names are used as item labels and the column names are stores as transaction IDs.

coerce

signature(from = "list", to = "transactions"); produces a transactions data set from a list. The names of the items in the list are used as item labels and the item IDs and the incidence matrix is produced automatically.

coerce

signature(from = "transactions", to = "matrix")

coerce

signature(from = "transactions", to = "list")

coerce

signature(from = "data.frame", to = "transactions"); recodes the data frame containing only categorical variables (all have to be factors) into a binary transaction data set. The needed number of dummy items are automatically generated. The item labels are generated by concatenating variable names and levels with a "=". The variable names and levels are stored in the labels data frame as the components variables and levels.

image

signature(x = "transactions"); plots an image of the transactions for visual inspection

labels

signature(x = "transactions"); returns the labels (item labels and transaction IDs) for the incidence matrix as a list of two vectors named items and transactionIDs.

transactionInfo<-

signature(x = "transactions"); replaces the transactionInfo data frame

transactionInfo

signature(x = "transactions"); returns transactionInfo

show

signature(object = "transactions")

summary

signature(object = "transactions")

Author(s)

Michael Hahsler

See Also

itemMatrix-class

Examples

data <- list(
      c("a","b","c"),
      c("a","b"),
      c("a","b","d"),
      c("c","e"),
      c("a","b","d","e"),
      )

names(data) <- paste("Tr",c(1:5), sep = "")

### coerce data into transactins
trans <- as(data, "transactions")

### analyze transactions
summary(trans)
image(trans)