Read Transaction Data
Reads a transaction data file from disk and creates a
transactions
object.
read.transactions(file, format = c("basket", "single"), header = FALSE, sep = "", cols = NULL, rm.duplicates = FALSE, quote = "\"'", skip = 0, encoding = "unknown")
file |
the file name or connection. |
format |
a character string indicating the format of the data
set. One of |
header |
a logical value indicating whether the file contains the names of the variables as its first line. |
sep |
a character string specifying how fields are separated in
the data file. The default ( |
cols |
For the ‘single’ format, |
rm.duplicates |
a logical value specifying if duplicate items should be removed from the transactions. |
quote |
a list of characters used as quotes when reading. |
skip |
number of lines to skip in the file before start reading data. |
encoding |
character string indicating the encoding which is passed to
|
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.
Returns an object of class
transactions
.
Michael Hahsler and Kurt Hornik
## create a demo file using basket format for the example data <- paste( "# this is some test data", "item1, item2", "item1", "item2, item3", sep="\n") cat(data) write(data, file = "demo_basket.txt") ## read demo data (skip the comment in the first line) tr <- read.transactions("demo_basket.txt", format = "basket", sep=",", skip = 1) inspect(tr) ## make always sure that the items were properly separated itemLabels(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.txt") ## read demo data tr <- read.transactions("demo_single.txt", format = "single", cols = c(1,2)) inspect(tr) ## create a demo file using single format with column headers data <- paste( "item_id;trans_id", "item1;trans1", "item1;trans2", "item2;trans2", sep ="\n") cat(data) write(data, file = "demo_single.txt") ## read demo data tr <- read.transactions("demo_single.txt", format = "single", header = TRUE, sep = ";", cols = c("trans_id","item_id")) inspect(tr) ## tidy up unlink("demo_basket.txt") unlink("demo_single.txt")
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