[R] Arules Package: Rules subset with 'empty' left hand side (lhs)
Tom D. Harray
tomdharray at gmail.com
Mon Sep 12 16:39:06 CEST 2016
Hello,
subsets of association rules (with respect to support, confidence, lift, or
items) can be obtained with the arules::subset() function; e.g.
rm(list = ls(all.names = TRUE))
library(arules)
set.seed(42)
x <- lapply(X = 1:500, FUN = function(i)
sample(x = 1:10, size = sample(1:5, 1), replace = FALSE)
)
x <- as(x, 'transactions')
rules <- apriori(
data = x,
parameter = list(target = 'rules', minlen = 1, maxlen = 2,
support = 0.10, confidence = 0.32)
)
rules <- arules::sort(x = rules, decreasing = TRUE, by ='support')
gives the rules
3 {} => {1} 0.330 0.3300000 1.0000000
2 {} => {3} 0.326 0.3260000 1.0000000
1 {} => {2} 0.320 0.3200000 1.0000000
20 {3} => {1} 0.120 0.3680982 1.1154490
21 {1} => {3} 0.120 0.3636364 1.1154490
16 {4} => {3} 0.114 0.3677419 1.1280427
(...)
However, I cannot figure out (help/web) how to get the subset for the rules
with empty left hand side (lhs) like subset(rules, lhs == ''). I could run the
apriori() function twice and adjust the min/maxlen parameters as a band
aid fix.
So my question is: How do I subset() association rules with empty lhs?
Thanks and regards,
Dirk
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