Provides the generic function and the method `is.generator() for finding generator itemsets. Generators are part of concise representations for frequent itemsets. A generator in a set of itemsets is an itemset that has no subset with the same support (Liu et al, 2008). Note that the empty set is by definition a generator, but it is typically not stored in the itemsets in arules.
Value
a logical vector with the same length as x indicating for
each element in x if it is a generator itemset.
References
Yves Bastide, Niolas Pasquier, Rafik Taouil, Gerd Stumme, Lotfi Lakhal (2000). Mining Minimal Non-redundant Association Rules Using Frequent Closed Itemsets. In International Conference on Computational Logic, Lecture Notes in Computer Science (LNCS 1861). pages 972–986. doi:10.1007/3-540-44957-4_65
Guimei Liu, Jinyan Li, Limsoon Wong (2008). A new concise representation of frequent itemsets using generators and a positive border. Knowledge and Information Systems 17(1):35-56. doi:10.1007/s10115-007-0111-5
See also
Other postprocessing:
is.closed(),
is.maximal(),
is.redundant(),
is.significant(),
is.superset(),
ruleInduction()
Other associations functions:
abbreviate(),
associations-class,
c,
duplicated(),
extract,
inspect(),
is.closed(),
is.maximal(),
is.redundant(),
is.significant(),
is.superset(),
itemsets-class,
match(),
rules-class,
sample(),
sets,
size(),
sort(),
unique()
Examples
# Example from Liu et al (2008)
trans_list <- list(
t1 = c("a", "b", "c"),
t2 = c("a", "b", "c", "d"),
t3 = c("a", "d"),
t4 = c("a", "c")
)
trans <- transactions(trans_list)
its <- apriori(trans, support = 1 / 4, target = "frequent itemsets")
#> Apriori
#>
#> Parameter specification:
#> confidence minval smax arem aval originalSupport maxtime support minlen
#> NA 0.1 1 none FALSE TRUE 5 0.25 1
#> maxlen target ext
#> 10 frequent itemsets TRUE
#>
#> Algorithmic control:
#> filter tree heap memopt load sort verbose
#> 0.1 TRUE TRUE FALSE TRUE 2 TRUE
#>
#> Absolute minimum support count: 1
#>
#> set item appearances ...[0 item(s)] done [0.00s].
#> set transactions ...[4 item(s), 4 transaction(s)] done [0.00s].
#> sorting and recoding items ... [4 item(s)] done [0.00s].
#> creating transaction tree ... done [0.00s].
#> checking subsets of size 1 2 3 4 done [0.00s].
#> sorting transactions ... done [0.00s].
#> writing ... [15 set(s)] done [0.00s].
#> creating S4 object ... done [0.00s].
is.generator(its)
#> {d} {b} {c} {a} {b,d} {c,d} {a,d} {b,c}
#> TRUE TRUE TRUE FALSE TRUE TRUE FALSE FALSE
#> {a,b} {a,c} {b,c,d} {a,b,d} {a,c,d} {a,b,c} {a,b,c,d}
#> FALSE FALSE FALSE FALSE FALSE FALSE FALSE