read.transactions {arules}R Documentation

Read Transaction Data

Description

Reads a transaction data file from disk and creates a transactions object.

Usage

read.transactions(file, format = c("basket", "single"), sep = NULL,
                  cols = NULL, rm.duplicates = FALSE, encoding = "unknown")

Arguments

file

the file name.

format

a character string indicating the format of the data set. One of "basket" or "single", can be abbreviated.

sep

a character string specifying how fields are separated in the data file, or NULL (default). For basket format, this can be a regular expression; otherwise, a single character must be given. The default corresponds to white space separators.

cols

For the ‘single’ format, cols is a numeric or character vector of length two giving the numbers or names of the columns (fields) with the transaction and item ids, respectively. If character, the first line of file is assumed to be a header with column names. For the ‘basket’ format, cols can be a numeric scalar giving the number of the column (field) with the transaction ids. If cols = NULL, the data do not contain transaction ids.

rm.duplicates

a logical value specifying if duplicate items should be removed from the transactions.

encoding

character string indicating the encoding which is passed to readlines (see Encoding).

Details

For ‘basket’ format, each line in the transaction data file represents a transaction where the items (item labels) are separated by the characters specified by sep. For ‘single’ format, each line corresponds to a single item, containing at least ids for the transaction and the item.

Value

Returns an object of class transactions.

See Also

transactions-class

Examples

## create a demo file using basket format for the example
data <- paste("item1,item2","item1","item2,item3", sep="\n")
cat(data)
write(data, file = "demo_basket")

## read demo data
tr <- read.transactions("demo_basket", format = "basket", sep=",")
inspect(tr)


## create a demo file using single format for the example
## column 1 contains the transaction ID and column 2 contains one item
data <- paste("trans1 item1", "trans2 item1","trans2 item2", sep ="\n")
cat(data)
write(data, file = "demo_single")

## read demo data
tr <- read.transactions("demo_single", format = "single", cols = c(1,2))
inspect(tr)


## tidy up
unlink("demo_basket")
unlink("demo_single")


[Package arules version 1.0-7 Index]