I'm looking at this data set: https://archive.ics.uci.edu/ml/machine-learning-databases/credit-screening/crx.data
I preprocessed the data:
ca.1<-read.csv("CreditApproval.csv",T,",")
# From http://stackoverflow.com/q/4787332/
remove_outliers <- function(x, na.rm = TRUE, ...) {
qnt <- quantile(x, probs=c(.25, .75), na.rm = na.rm, ...)
H <- 1.5 * IQR(x, na.rm = na.rm)
y <- x
y[x < (qnt[1] - H)] <- NA
y[x > (qnt[2] + H)] <- NA
y
}
ca.1$A2<-remove_outliers(ca$A2)
ca.1$A3<-remove_outliers(ca$A3)
ca.1$A8<-remove_outliers(ca$A8)
ca.1$A11<-remove_outliers(ca$A11)
ca.1$A14<-remove_outliers(ca$A14)
ca.1$A15<-remove_outliers(ca$A15)
ca.1$A2<-discretize(ca.1$A2,"frequency",categories = 6)
ca.1$A3<-discretize(ca.1$A3,"frequency",categories = 6)
ca.1$A8<-discretize(ca.1$A8,"frequency",categories = 6)
ca.1$A11<-discretize(ca.1$A11,"frequency",categories = 6)
ca.1$A14<-discretize(ca.1$A14,"frequency",categories = 6)
ca.1$A15<-discretize(ca.1$A15,"frequency",categories = 6)
ca.1<-na.omit(ca.1)
After fine tuning the support, confidence, min/maxlen I'm still getting 65 rules:
> rules<-apriori(ca.1, parameter= list(supp=0.15, conf=0.89, minlen=3, maxlen=4), appearance=list(rhs=c("class=-", "class=+"), default="lhs"))
> rules.sorted <- sort(rules, by="lift")
> inspect(rules.sorted)
lhs rhs support confidence lift
[1] {A5=g,A9=t,A10=t} => {class=+} 0.1521739 0.8974359 2.770607
[2] {A4=u,A9=t,A10=t} => {class=+} 0.1521739 0.8974359 2.770607
[3] {A1=a,A9=f} => {class=-} 0.1717391 0.9753086 1.442579
[4] {A1=a,A9=f,A13=g} => {class=-} 0.1608696 0.9736842 1.440176
...[65]
As you can see +
rules have a greater lift, but less support and confidence than the -
rules. I've been looking through the docs, and can't find any parameter to limit by lift. Is this possible? If not, what do you do in situations like this?