R/hill_utils.R

In tcpl: ToxCast Data Analysis Pipeline

#' @name Hill model utilites
#' @rdname hill_utils
#' @title Functions to solve the Hill model
#' 
#' @description 
#' These functions solve for Hill model parameters. 
#' 
#' @details
#' \code{tcplHillVal} computes the value of the Hill model for a given log 
#' concentration. 
#' 
#' \code{tcplHillACXX} computes the activity concentration for a Hill model for 
#' a given activity level.
#' 
#' \code{tcplHillConc} computes the Hill model concentration for a 
#' given value.
#' 
#' @param XX Numeric, the activity level (percentage of the top value)
#' @param val Numeric, the activity value
#' @param logc Numeric, the log concentration
#' @param tp Numeric, the top value from the Hill model
#' @param ga Numeric, the logAC50 value from the Hill model
#' @param gw Numeric, the Hill coefficient from the Hill model
#' @param bt Numeric, the bottom value from the Hill model
#' 
#' @examples
#' ## The following code gives examples for a Hill model with a top of 50, 
#' ## bottom of 0, AC50 of 1 and Hill coefficient of 1.
#' ## tcplHillVal calculates activity value given a concentration. tcplHillVal
#' ## will return the tp/2 when logc equals ga:
#' tcplHillVal(logc = 1, tp = 50, ga = 1, gw = 1, bt = 0)
#' 
#' ## Here, tcplHillConc returns the concentration where the value equals 20
#' tcplHillConc(val = 20, tp = 50, ga = 1, gw = 1, bt = 0)
#' 
#' ## Note how this differs from tcplHillACXX:
#' tcplHillACXX(XX = 20, tp = 50, ga = 1, gw = 1, bt = 0)
#' 
#' ## tcplHillACXX is based on the top value and allows the user to calculate 
#' ## specifc activity concentrations based on a percentage of the top value
#' 
#' ## For example, we can calculate the value for the concentration 0.25, then
#' ## use that value to check the other two functions.
#' 
#' value <- tcplHillVal(logc = 0.25, tp = 50, ga = 1, gw = 1, bt = 0)
#' c1 <- tcplHillConc(val = value, tp = 50, ga = 1, gw = 1, bt = 0)
#' c2 <- tcplHillACXX(XX = value/50*100, tp = 50, ga = 1, gw = 1, bt = 0)
#' all.equal(0.25, c1, c2)
#' 
#' ## Notice, the value had to be transformed to a percentage of the top value
#' ## when using tcplHillACXX

NULL