R/growth_rate.R

In EcoNum/coral.growth: Use of buoyant weight to compute the growth rate

#' Compute the growth rate
#'
#' @description The determination of the growth rate is a important parameter. Indeed, the growth rate can be used to compare different individuals. There are several methods to compute the growth rate.
#'
#' @param skw_t The weight at time t
#' @param skw_ini The weight at initial time
#' @param date_t The number day at time t
#' @param date_ini The number day at initial time
#' @param method The method to be employed. See the description to know the different methods
#'
#' @return The growth rate
#' @export
#'
#' @examples
#'
#' growth_rate(skw_t = 1.2, skw_ini = 1, date_t = 7, date_ini = 0,
#' method = "exponential")
#'
#' # See \url{https://econum.github.io/coral.growth/articles/} for more examples
#'
growth_rate <- function(skw_t, skw_ini, date_t, date_ini = 0,
                        method = c("exponential", "linear", "linear_std")) {
  method <- match.arg(method)
  switch(method,
         exponential = log(skw_t/skw_ini) / (date_t - date_ini) * 100,
         linear      = (skw_t - skw_ini) / (date_t - date_ini),
         linear_std  = (skw_t - skw_ini) / skw_ini / (date_t - date_ini) * 100
  )
}