R/search_rule.R

In gaiac/TFARM: Transcription Factors Association Rules Miner

#' Finds an association rule in a dataset.
#'
#' The function looks for an association rule in a dataset \code{data}
#' with a fixed left-hand-side (\code{LHS}) and a fixed right-hand-side
#' (\code{RHS}). The function is used in the \code{rulesTF0}.
#' @param data a binary matrix or data.frame in which the rule is searched
#' @param LHS a string with the left-hand-side of the searched rule
#' @param RHS a string with the right-hand-side of the searched rule
#'
#' @return A vector with five elements: the left-hand-side of the searched rule,
#' the right-hand-side of the searched rule, the support, confidence and lift
#' of the found rule.
#' @export
#' @import arules

search_rule <- function(data, LHS, RHS) {

    m <- dim(data)[2]
    data.f <- data
    # Transactions extraction
    for (i in 1:m) {
        data.f[, i] <- as.factor(data.f[, i])
    }
    # Rules extraction
    rule <- apriori(data.f, parameter = list(supp = 0, conf = 0, target = "rules"),
                    appearance = list(lhs = items(LHS), rhs = RHS, default = "none"),
                    control = list(sort = 2, verbose = FALSE))
    if (length(rule) == 0) {
        print("Rule not found")
        r <- NA
    } else if (length(rule) > 0) {
        r_0 = data.frame(lhs = labels(lhs(rule)), rhs = labels(rhs(rule)),
                         rule@quality)
        r <- r_0[r_0$lhs == LHS, ]
        if (dim(r)[1] == 0) {
            print("Rule not found")
            r <- NA
        }
    }
    return(r)
}