R/make_legend_ggplot.R

In BCEA: Bayesian Cost Effectiveness Analysis

#' @noRd
#' @title make_legend_ggplot
#' 
#' @description c(0, 0) corresponds to the “bottom left”
#'  c(1, 1) corresponds to the “top right”
#'  inside the plotting area
#' 
#' @param dat data
#' @param legend_pos Legend position
#'
#' @keywords internal
#' 
make_legend_ggplot <- function(dat, legend_pos) {
  
  legend_just <- NULL  # sets the corner that the legend_pos position refers to
  legend_dir <- NULL
  
  n_lines <- num_lines(dat)
  
  if (n_lines == 1) {
    
    legend_pos <- "none"
    
  } else if (any(is.na(legend_pos))) {
    
    legend_pos <- "none"
    
  } else if (is.logical(legend_pos)) {
    
    if (isTRUE(legend_pos)) {
      legend_pos <- "bottom"
    } else {
      legend_pos <- c(1, 0)
      legend_just <- legend_pos 
    }
  } else if (is.character(legend_pos)) {
    
    pos_choices <- c("left", "right", "bottom", "top")
    legend_pos <- pos_choices[pmatch(legend_pos, pos_choices)]
    legend_just <- "center"
  } else if (is.numeric(legend_pos) &&
             length(legend_pos) == 2) {
    
    legend_just <- legend_pos
  } else {
    # default
    legend_pos <- c(1, 0)
    legend_just <- legend_pos
  } 
  
  list(legend.direction = legend_dir,
       legend.justification = legend_just,
       legend.position = legend_pos)
}