R/dfapply.R

In ProjectMOSAIC/mosaicCore: Common Utilities for Other MOSAIC-Family Packages

#' apply-type function for data frames
#'
#' An `apply`-type function for data frames.
#' @param data  data frame
#' @param FUN
#'   a function to apply to (some) variables in the data frame
#' @param select a logical, character (naming variables), or numeric vector or a
#'   function used to select variables to which `FUN` is applied.  If a function,
#'   it should take a vector as input and return a single logical. See examples.
#' @param \dots arguments passed along to `FUN`
#'
#' @seealso [apply()],
#' [sapply()],
#' [tapply()],
#' [lapply()],
#' [inspect()]
#'
#' @examples
#' dfapply(iris, mean, select = is.numeric)
#' dfapply(iris, mean, select = c(1,2))
#' dfapply(iris, mean, select = c("Sepal.Length", "Petal.Length"))
#' if (require(mosaicData)) {
#'   dfapply(HELPrct, table, select = is.factor)
#'   do.call(rbind, dfapply(HELPrct, mean, select = is.numeric))
#' }
#' @export

dfapply <-
  function (data, FUN, select = TRUE, ...)
  {
    if (is.function(select)) {
      select <- sapply(data, select)
    }
    if (is.logical(select)) {
      select <- rep(select, length.out = dim(data)[2])
      select <- which(select)
    }
    if (is.character(select)) {
      select <- sapply(select, function(x) which (x == names(data)))
    }
    if (!is.numeric(select)) {
      stop("Unusable selection parameter.")
    }
    lapply(data[, select, drop = F], FUN, ...)
  }