hexamapmaker: Turns Points into Hexagons

#' Turns a set of points into hexagons
#'
#' @name make_polygons
#'
#' @param z A data frame containing x, y and id.
#'
#' @description
#' make_polygons takes a set of points (x and y coordinates) and turns them into hexagons.
#' The idea is, that you can quickly design the layout of a hexagon map by just adding points in a coordinate system. Then the hexamap function turns them into hexagon-shaped polygons that can be plotted with ggplot2.
#'
#' @return
#' The function returns a set of hexagons.
#'
#' @export
#'
#' @examples
#' # Load libraries
#' library(hexamapmaker)
#' library(ggplot2)
#' library(tibble)
#' library(ggthemes)
#'
#' # Points on a "normal" grid.
#' my_points <- tibble::tibble(
#'   x = c(1, 2, 1, 2, 1, 2, 4, 4),
#'   y = c(1, 1, 2, 2, 3, 3, 1, 2),
#'   id = c("test1", "test2", "test3", "test4", "test5", "test6", "test7", "test8")
#' )
#'
#' # Plot the points
#' ggplot(my_points, aes(x = x, y = y, group = id)) +
#'   geom_point() +
#'   coord_fixed(ratio = 1) +
#'   theme_map()
#'
#' # Turn points into hexagons
#' hexa_points <- make_polygons(my_points)
#'
#' # Plot the new hexagons
#' ggplot(hexa_points, aes(x, y, group = id)) +
#'   geom_polygon(colour = "black", fill = NA) +
#'   coord_fixed(ratio = 1) +
#'   theme_map()
#'
#' # Oh no! It is way off - lets fix it.
#' my_points <- fix_shape(my_points)
#'
#' # Plot points
#' ggplot(my_points, aes(x = x, y = y, group = id)) +
#'   geom_point() +
#'   coord_fixed(ratio = 1) +
#'   theme_map()
#'
#' # Turn points into hexagons
#' hexa_points <- make_polygons(my_points)
#'
#' ggplot(hexa_points, aes(x, y, group = id)) +
#'   geom_polygon(colour = "black", fill = NA) +
#'   coord_fixed(ratio = 1) +
#'   theme_map()
#'
#' # Add color by using the fill argument in ggplot.
#' # Remember to remove it from the geom_polygon then
#' (p <- ggplot(hexa_points, aes(x, y, group = id, fill = id)) +
#'     geom_polygon(colour = "black", show.legend = FALSE) +
#'     coord_fixed(ratio = 1) +
#'     theme_map())
#'
#' # Label hexagons
#' add_hexalabel(hexa_points, p)
make_polygons <- function(z){

  hexadata <- tibble::tibble()

  for(i in z$id){

    mydata <- z[z$id == i,]
    x <- mydata$x + c(-1, -1, 0, 1, 1, 0)
    y <- mydata$y + c(0, 1, 1.577, 1, 0, -0.577)

    multiplier <- (mydata$y-1)/2

    y <- y - 0.423 * multiplier

    mydata <- tibble::tibble(id = i, x, y)

    hexadata <- dplyr::bind_rows(hexadata, mydata)
  }

  message(praise::praise("${EXCLAMATION}! Your new hexagon map is ${adjective}!"))

  return(hexadata)
}