R/PeakFunctions_func_gaussian.R

In pmbrophy/SummitR: Provides a set of tools for peak fitting

#' Calculate Normal Distribution or Gaussian Peak
#'
#' Calculates either a normal distribution similar to dnorm() with an
#' integrated area of 1 or a gaussian peak with amplitude k
#'
#' @param x a vector of x-coordinates from which the corrisponding y-coordinates
#'   are calculated
#' @param mu the mean
#' @param sigma the standard deviation
#' @param probDensity Should the function produce a probability density function
#'   `TRUE` or a gaussian peak `FALSE` with amplitude k? default is `TRUE`.
#' @param k Amplitude of the peak. Only used when `probDensity == FALSE`
#'
#' @return a vector of y-coordinates the same length as x
#' @export
#'
#' @examples
#' #normal distribution
#' xVec <- seq(from = 1, to = 100, by = 0.1)
#' pdensity <- func_gaussian(x = xVec, mu = 10, sigma = 1, probDensity = TRUE)
#' p1 <- plot(x = xVec, y = pdensity)
#'
#' #gaussian peak
#' gpeak <- func_gaussian(x = xVec, mu = 10, sigma = 1, probDensity = FALSE, k = 10)
#' p2 <- plot(x = xVec, y = gpeak)
#'

func_gaussian <- function(x, mu, sigma, probDensity = TRUE, k){
  if(probDensity){
    k <- (1/(sigma*sqrt(2*pi)))
  }else{
    if(missing(k)){
      stop("k not specified")
    }
  }

  peak <- k * exp(-0.5 * ((x-mu)/sigma)^2)

  peak
}