Ewa Janikowska Ewa Janikowska - 21 days ago 6
R Question

How to sort association rules by lhs or rhs in R

I have set of rules from apriori algorithm. Sorting them by lift, confidence or support is easy:

rules.sorted = sort(rules, by="lift")


But let's say I have small set of rules with a few different rhs elements.
I would like to view rules sorted by those rhs elements (alphabetically). Is there a way to do that?

I.e from this:

lhs rhs support confidence lift
1 {A} => {B} 0.3919252 0.9431280 1.930940
2 {B} => {A} 0.3919252 0.8024194 1.930940
3 {E,C} => {A} 0.3535204 0.7995546 1.924047
4 {F,I} => {F} 0.3924175 0.9005650 1.868281
5 {H} => {G} 0.4194978 0.9659864 1.864941
6 {C,D} => {A} 0.3653373 0.7141482 1.718525


To this:

lhs rhs support confidence lift

2 {B} => {A} 0.3919252 0.8024194 1.930940
3 {E,C} => {A} 0.3535204 0.7995546 1.924047
6 {C,D} => {A} 0.3653373 0.7141482 1.718525
1 {A} => {B} 0.3919252 0.9431280 1.930940
4 {F,I} => {F} 0.3924175 0.9005650 1.868281
5 {H} => {G} 0.4194978 0.9659864 1.864941


Here is an example of rules that I work with:

library(arules)
download.file("http://archive.ics.uci.edu/ml/machine-learning-databases/mushroom/agaricus-lepiota.data", "mush.data");
dataset = read.table("mush.data", header = F, sep=",", na.strings= "*")
tr <- as(dataset, "transactions")
param = new("APparameter", "confidence" = 0.9, "support" = 0.7, "minlen"= 2L, "maxlen" = 2L, "target" = "rules")
rules <-apriori(tr,param)
dput(rules)

Answer

Extract basic information from your rules object to a data frame, like this:

rules_info <-
  data.frame(
    LHS = labels(lhs(rules)), 
    RHS = labels(rhs(rules)),          
    quality(rules)
  )

Then sort it like a normal data frame:

rules_info[ order(rules_info$RHS), ]