8.5 apriori train


ml train apriori [options] [file.csv]
     -c <0-1>      --confidence=<0-1>   Minimum confidence threshold.
                   --id=<name>          The id column name.
     -o <file>     --output=<file>      Save itemsets to .csv or .rds file.
     -s <0-1>      --support=<0-1>      Minimum support threshold.

Input file is a two column csv file. One column is the basket id and the other is an item in that basket. The item column can have any name. If no data file is supplied the data is read from stdin, often as part of a pipeline. An example input data file might be:


Output to stdout (by default) is a row for each association rule, together with a number of measures of the quality of the rule:

$ ml train apriori mcomp.csv

The count for a rule A=>B is the number of transactions that contain the items in A and B. The support is the proportion of transactions that contain A and B (i.e., the count over the total number of transactions in the dataset). The confidence is the probability of B being in a transaction whenever A is in then transaction (i.e., the count over the total number of transactions that contain A). The coverage is the proportion of transactions that contain A. The lift is a measure of the correlation between A and B. If it is 1 then there is no correlation. Above 1 is a positive correlation and below 1 is a negative correlation.

As with itemsets, the output can be saved to a named csv file using --output= (or -o), with the argument being a filename including the .csv extension. If the filename extension is instead .rds then the result is saved as a single object in the named file.

ml train apriori -o rules.csv mcomp.csv
ml train apriori -o rules.rds mcomp.csv

Other options are similar to itemsets with the addition of --confidence (-c) as a minimum threshold for the confidence of the rules that we are interested in.

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