Hi all,
There is no item with the label "".
> itemLabels(rules)
[1] "1" "2" "3" "4" "5" "6" "7" "8" "9" "10"
arules::subset(rules, subset=lhs %pin% "") should return an empty set or
throw an error---I will fix that in the next release of arules.
To get the rules with 0 elements in the lhs do this:
> r0 <- rules [size(lhs(rules))==0]
> inspect(r0)
lhs rhs support confidence lift
3 {} => {1} 0.330 0.330 1
2 {} => {3} 0.326 0.326 1
1 {} => {2} 0.320 0.320 1
Hope this helps,
Michael
On 09/13/2016 08:30 AM, Tom D. Harray wrote:
Hello Luisfo,
thank you for the hint: Your suggestion
arules::subset(rules, subset=lhs %pin% "")
gave 18 rules (out of 21) in my example, and not 3, what I have expected.
Surprisingly the negation of the subset condition
arules::subset(x = rules, subset = !(lhs %pin% ""))
returns the 3 rules with empty lhs.
Hello Martin,
I add you to this thread, because the arules::subset() behaviour
appears to me to be a bug in arules. And I'd like to suggest to add an
explanation/example to arules::subset() help.
Cheers,
Dirk
On 13 September 2016 at 05:10, Luisfo <luisf...@yahoo.es> wrote:
Dear Tom,
I think this is the line you need
arules::subset(rules, subset=lhs %pin% "")
I found the solution here:
http://stackoverflow.com/questions/27926131/how-to-get-items-for-both-lhs-and-rhs-for-only-specific-columns-in-arules
One more thing. For printing the rules, I needed the inspect() command you
didn't provide.
I hope this helps.
Best,
Luisfo Chiroque
PhD Student | PhD Candidate
IMDEA Networks Institute
http://fourier.networks.imdea.org/people/~luis_nunez/
On 09/12/2016 04:39 PM, Tom D. Harray wrote:
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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