R/transform.R

In nfrerebeau/codex: Tools for Cleaning Rectangular Data

# DATA TRANSFORMATION
NULL

#' Rescale Continuous Vector (minimum, maximum)
#'
#' Rescales continuous vector to have specified minimum and maximum.
#' @param x A [`numeric`] vector.
#' @param to A length-two [`numeric`] vector specifying the output range.
#' @param from A length-two [`numeric`] vector specifying the input range.
#' @return A [`numeric`] vector.
#' @note For internal use only.
#' @family data transformation tools
#' @export
scale_range <- function(x, to = c(0, 1), from = range(x, finite = TRUE)) {
  (x - from[1L]) / diff(from) * diff(to) + to[1L]
}

#' Rescale Continuous Vector (minimum, midpoint, maximum)
#'
#' Rescales continuous vector to have specified minimum, midpoint and maximum.
#' @param x A [`numeric`] vector.
#' @param to A length-two [`numeric`] vector specifying the output range.
#' @param from A length-two [`numeric`] vector specifying the input range.
#' @param midpoint A length-one [`numeric`] vector specifying the mid-point of input
#'  range.
#' @return A [`numeric`] vector.
#' @note For internal use only.
#' @family data transformation tools
#' @export
scale_midpoint <- function(x, to = c(0, 1), from = range(x, finite = TRUE), midpoint = 0) {
  extent <- 2 * max(abs(from - midpoint))
  (x - midpoint) / extent * diff(to) + mean(to)
}