read_transactions
uses (internally) the readChar
function to read transaction data from a file fast. This is substantially
faster for larger files than alternative methods.
Files should be in the format of a list of transactions, one line per
transaction, each transaction (ie, line) being a sequence of item labels,
separated by the character specified by the parameter sep
(default "
"). See, for example, the files at http://fimi.ua.ac.be/data/.