R/consens.R

In dco61/isteahMAT104: MAT104 Probabilité et Statistiques

#'
#'Compute consensus for ordinal data sets
#'@param x a ordinal data vector
#'@param tbl Logical TRUE/FALSE: Table data or Raw data (default)
#'@return consensus index (according to Tatsle & Wierman (2007))
#'@examples
#'cons <- consens(sample(1:7,200,replace=TRUE),tbl=FALSE)
#'@export
consens <- function(V, tbl = FALSE) {
    # input validation: is this a frequency vector?
    if (!tbl) {
        V <- table(V)
    }
    if (min(V) < 0)
        stop("Error: negative values found in frequency vector.")
    if (all(round(V, 0) == V) == FALSE)
        stop("Error: not all values are whole numbers; not a frequency vector; multiply by 100?")

    P <- V/sum(V)  # normalizing the vector
    pos <- 1:length(V)
    mx <- mean(expand(V))
    dx <- max(pos) - min(pos)
    cns <- 1 + sum(P * log2(1 - abs(pos - mx)/dx))
    if (max(V) == sum(V))
        cns <- 1
    return(cns)
}