Frequent Itemsets beyond Level 10 are not checked

[lord-blueberry]

Imagine Transactions with sizes of up to 15 Items. With a low support, arules does not check Itemsets of Level 10 correctly. Every Itemset of length 10 and more is always not frequent.

I compared the results with the output of the latest Borgelt Apriori implementation. Every retrieved Frequent Itemset is identical up to Level 9, after which they are simply missing.

[lord-blueberry]

OK this is my fault, I did not see the Parameter "maxlen" which defaults to 10. In the latest Borgelt implementation this Parameter defaults to infinity. IMO infinity is a more useful default value, because the Apriori Algorithm is defined to check all Itemsets which are over the minSupport threshold regardless of length.

[mhahsler]

While infinity theoretically a good idea, lots of people specify a minimum support which is too low and then they run out of memory. maxlen 10 at least sets a boundary and hopefully does not send your system into memory thrashing...