R/conversion.R

In wfondrie/evrspin: Calculations for Extracellular Vesicle Sedimentation by Centrifugation

#' RCF and RPM Conversions
#' @description Convert RCF to RPM, or vice versa, for a given rotor.
#' @param rcf The relative centrifugal force.
#' @param rpm The revolutions per minute.
#' @param rotor A rotor object, created with \code{rotor()}.
#'
#' @return \code{rcf2rpm} returns the rpm equilavent to the specified rotor and
#' rcf. Likewise, \code{rpm2rcf} returns the rcf for the specified rotor and rpm.
#'
#' @examples
#' # Create a Beckman SW 40 Ti rotor object
#' sw40 <- rotor(model = "sw40")
#'
#' # Calculate the rpm needed for 10,000 x g
#' rcf2rpm(10000, sw40)
#'
#' # Calculate the rcf for an SW 40 Ti rotor spinning at 1,000 rpm
#' rpm2rcf(1000, sw40)
#'
#' @section Warning: Check your owner's manual for the maximum rpm and rcf
#' ratings of your rotor before proceeding.
#'
#' @export

rcf2rpm <- function(rcf, rotor) {

  # Check Arguments ------------------------------------------------------------
  if(!is.numeric(rcf)) stop("rcf must be numeric.")
  if(class(rotor) != "rotor") stop("rotor is not a rotor-class object. Use rotor() to create one.")

  # Calculation ----------------------------------------------------------------
  rpm <- sqrt(rcf / (rotor[["R.ave"]] * 1.12)) * 1000

  return(rpm)
}


#' @rdname rcf2rpm
#' @export

rpm2rcf <- function(rpm, rotor) {

  # Check Arguments ------------------------------------------------------------
  if(!is.numeric(rpm)) stop("rpm must be numeric.")
  if(class(rotor) != "rotor") stop("rotor is not a rotor-class object. Use rotor() to create one.")

  # Calculation ----------------------------------------------------------------
  rcf <- (rpm/1000)^2 * rotor[["R.ave"]] * 1.12

  return(rcf)
}