Error deploying azure ML experiment with R script for mining association rules

Question

I have created a new experiment on Azure Machine Learning studio that through the module Execute R Script is able to do the mining of the association rules from the starting dataset. For this experiment I used the R version Microsoft R Open 3.2.2

The function used in the experiment on Azure ML, I first wrote and tested it on R studio, where I did not have any kind of problem. This is the structure of my experiment:

and this is a part of code inserted inside the module on Azure ML that on R Studio works properly:

# Map 1-based optional input ports to variables
dataset1 <- maml.mapInputPort(1) # class: data.frame

library("arules")
library("sqldf")

x <- sqldf('select ID_Ordine, AnnoOrdine, ZonaCommerciale, Modello, SUM(Qta) as Qta 
            from dataset1 group by ID_Ordine, Modello order by ID_Ordine')

a_list1 <- transform(x, Modello = as.factor(Modello),
                     ID_Ordine = as.factor(ID_Ordine)) 
transactions <- as(split(x[,"Modello"], x[,"ID_Ordine"]), "transactions")
rules <- sort(apriori(transactions,
                        parameter = list(supp = 0.1, conf = 0.1, target = "rules",
                                         maxlen = 5)), by="lift")
gi <- generatingItemsets(rules) #remove inverse duplicated rules
d <- which(duplicated(gi))      #remove inverse duplicated rules
rules <- rules[-d]              #remove inverse duplicated rules

#create a dataframe to be used as output
result <- data.frame(label_lhs = labels(lhs(rules)), 
                     label_rhs = labels(rhs(rules)),
                     count = quality(rules)["count"])
               
# Select data.frame to be sent to the output Dataset port
maml.mapOutputPort("result");

If I exclude this line from the code count = quality(rules)["count"] (the statement to import into the output dataframe the column relating to the count) the experiment works correctly, but when I also import the count column, the execution of the experiment gives me the following error:

Someone knows how to fix this error, or knows an alternative way to select the count column from the arules object recognized by Azure ML?

Thanks for any suggestions

Answer 1

The countcolumn is not calculated by the function apriori()in this version of the package arules, so I calculated it in this way, using the inverse formula to calculate the support:

#create a dataframe to be used as output
result <- data.frame(label_lhs = labels(lhs(rules)), 
                     label_rhs = labels(rhs(rules)),
                     count = quality(rules)$support*length(transactions))

because the support is calculated with the following formula:

support = (number of transactions with A&B)/(number of total transactions)