R/fidelity_funs_calc-coords-from-step.R

In picardis/fidelity: Generate Null Expectations for Animal Site Fidelity

#' Calculate End Point Coordinates
#'
#' Function to calculate end point coordinates from step and turning angle.
#' Called by \code{sim_bcrw()}.
#'
#' Code adapted from https://rdrr.io/github/ptompalski/UsefulRFunctions/src/R/circular2xy.R
#' @param step Numeric. Step length (m for UTM coordinates, degrees for lat/long)
#' @param angle Numeric. Turning angle (degrees)
#' @param start_x Numeric. The X coordinate of the start location (UTM Easting
#' or longitude)
#' @param start_y Numeric. The Y coordinate of the start location (UTM Northing
#' or latitude)
#' @return A data frame containing the end points coordinates from the step and
#' turning angle input.
#' @export
end_coords <- function(step,
                       angle,
                       start_x,
                       start_y
                       ) {

  delta_x <- step * cos(angle)
  delta_y <- step * sin(angle)
  end_x <- start_x + delta_x
  end_y <- start_y + delta_y
  return(data.frame(x = end_x, y = end_y))

}