How to extract information from apriori R (association rules)
I am doing some association rules in R and want to extract my results so that I can generate reports my results look like this:
> inspect(rules[1:3])
lhs rhs support confidence lift
1 {apples} => {oranges} 0.00029 0.24 4.4
2 {apples} => {pears} 0.00022 0.18 45.6
3 {apples} => {pineapples} 0.00014 0.12 1.8
How do I extract "rhs" here, i.e. vector oranges, pears and pineapples
Next, how do I extract information from a summary ie
> summary(rules)
The datatype is "s4" and has no problem fetching when the output is in a list, etc., how do you make equivalence? set of 3 rules
rule length distribution (lhs + rhs):sizes
2
3
Min. 1st Qu. Median Mean 3rd Qu. Max.
2 2 2 2 2 2
I want to extract "3" from the "set of three rules"
I've gotten to using "@" What does the @ symbol mean in R?
But once I use this, how can I turn my results into a vector ie
inspect(rules@rhs)
1 {oranges}
2 {pears}
3 {pineapples}
becomes a character vector of length 3
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inspect
returns nothing, just printing its output. When this happens, you can use the function capture.output
if you want to store the output as a string. For example, having receivedrhs
data(Adult)
rules <- apriori(Adult, parameter = list(support = 0.4))
inspect(rules[1:3])
# lhs rhs support confidence lift
# 1 {} => {race=White} 0.8550428 0.8550428 1
# 2 {} => {native-country=United-States} 0.8974243 0.8974243 1
# 3 {} => {capital-gain=None} 0.9173867 0.9173867 1
## Capture it, and extract rhs
out <- capture.output(inspect(rules[1:3]))
gsub("[^{]+\\{([^}]*)\\}[^{]+\\{([^}]*)\\}.*", "\\2", out)[-1]
# [1] "race=White" "native-country=United-States"
# [3] "capital-gain=None"
However, it looks like you can simply access this information from rules
using the functionrhs
str(rhs(rules)@itemInfo)
# 'data.frame': 115 obs. of 3 variables:
# $ labels :Class 'AsIs' chr [1:115] "age=Young" "age=Middle-aged" "age=Senior" "age=Old" ...
# $ variables: Factor w/ 13 levels "age","capital-gain",..: 1 1 1 1 13 13 13 13 13 13 ...
# $ levels : Factor w/ 112 levels "10th","11th",..: 111 63 92 69 30 54 65 82 90 91 ...
In general, use str
to see what objects are created so you can decide how to extract components.
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To answer your second question: length(rules)
Now about your first question:
library("arules")
data("Adult")
## Mine association rules.
rules <- apriori(Adult,parameter = list(supp = 0.5, conf = 0.9, target = "rules"))
summary(rules)
l = length(rules)
everything = labels(rules)
#print(everything)
cut = unlist(strsplit(everything,"=> "))[seq(2,2*l,by=2)]
print(cut)
Feel free if you have a question, it might be a little tight :-)
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You can extract the RHS as a character vector of element names (without extraneous text like "=>" or curly braces) like this:
rules@rhs@itemInfo$labels[rules@rhs@data@i+1]
The index values stored in rules@rhs@data@i
range from 0 to one less than the number of unique labels. So indexing the labels requires adding '1' to avoid trying to access the 0th element rules@rhs@itemInfo$labels
.
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