R/getEllipse.r

In jgodet/trackR: R tools and functions to compute jump analysis, describe and infer from single-molecule tracking data

# getEllipse.r
# written by JuG
# January 10 2018


#' Create coordinates of an ellipse from fit ellipse parameters
#' @author JuG
#' @description Create coordinates of an ellipse from fit ellipse parameters
#' @param fit a fit object from fitEllipse
#' @param n number of corrdinates points to build
#' @details
#' @examples
#'
#'
#' @return
#' @export

getEllipse <- function( fit, n=360 ) {
  # Calculate points on an ellipse described by
  # the fit argument as returned by fit.ellipse
  #
  # n is the number of points to render

  tt <- seq(0, 2*pi, length=n)
  sa <- sin(fit$angle)
  ca <- cos(fit$angle)
  ct <- cos(tt)
  st <- sin(tt)

  x <- fit$center[1] + fit$maj * ct * ca - fit$min * st * sa
  y <- fit$center[2] + fit$maj * ct * sa + fit$min * st * ca

  return(cbind(x=x, y=y))
}