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#' @title Compute statistical mode of a vector (value that occurs most frequently)
#'
#' @description
#' Works for integer, numeric, factor and character vectors.
#' The implementation is currently not extremely efficient.
#'
#' @param x [\code{vector}]\cr
#' Factor, character, integer, numeric or logical vector.
#' @param na.rm [\code{logical(1)}]\cr
#' If \code{TRUE}, missing values in the data removed.
#' if \code{FALSE}, they are used as a separate level and this level could therefore
#' be returned as the most frequent one.
#' Default is \code{TRUE}.
#' @param ties.method [\code{character(1)}]\cr
#' \dQuote{first}, \dQuote{random}, \dQuote{last}: Decide which value to take in case of ties.
#' Default is \dQuote{random}.
#' @return Modal value of length 1, data type depends on data type of \code{x}.
#' @export
#' @examples
#' computeMode(c(1,2,3,3))
computeMode = function(x, ties.method = "random", na.rm = TRUE) {
assertAtomicVector(x)
assertChoice(ties.method, c("first", "random", "last"))
assertFlag(na.rm)
tab = as.data.table(x)[, .N, by = x]
if (na.rm) tab = na.omit(tab)
ind = (tab$N == max(tab$N))
mod = tab$x[ind]
if (is.factor(mod))
mod = as.character(mod)
if (length(mod) > 1L)
ind = switch(ties.method, first = mod[1L], random = sample(mod, 1L), last = mod[length(mod)])
else mod
}
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