emu: Encuesta de Movilidad Uniandina

#' Adds a north symbol to a ggplot map
#'
#' This function inserts a pretty north symbol in a ggplot map
#' @param data The dataframe containing the spatial information for the box limits.
#' @param location string indicating the symbol's location in the plot. Possible options: "topleft" (default), "bottomright", "bottomleft" and "topright".
#' @param scale a variable (or vector of variables) quoted that you want to change to binary.
#' @param symbol number between 1 and 3 to choose a symbol (1: black, 2: grey, 3: white)
#' @param x.min if data is not defined, number with the minimum x coordinate. Useful for ggmap.
#' @param x.max if data is not defined, number with the maximum x coordinate. Useful for ggmap.
#' @param y.min if data is not defined, number with the minimum y coordinate. Useful for ggmap.
#' @param y.max if data is not defined, number with the maximum y coordinate. Useful for ggmap.
#' @param anchor named vector with coordinates to control the symbol position. For location = "topright", anchor defines the coordinates of the symbol's topright corner and so forth. The x coordinate must be named as x and the y coordinate as y.
#' @keywords binary answer survey
#' @return The binary answers, changing "no" or "none" to 0 and "yes" to 1.
#' @details
#' North symbols are included in the plot with the annotation_custom function, which do not works when used together with an empty call to ggplot (see last example). When it is convenient to use an empty call to ggplot, use north2 instead.
#' @examples
#' ## Not run:
#' library(sf)
#' data(domestic_violence)
#' ggplot(domestic_violence, aes(fill = Scaled)) +
#' geom_sf() +
#' north_map(domestic_violence, location = "bottomright", symbol = 3) +
#' scale_fill_continuous(low = "#fff7ec", high = "#7F0000")
## End(Not run)
#' @export

sm_north <- function (data = NULL, location = "topleft", scale = 0.1, symbol = 1,
          x.min, x.max, y.min, y.max, anchor = NULL)
{
  if (is.null(data)) {
    if (is.null(x.min) | is.null(x.max) | is.null(y.min) |
        is.null(y.max)) {
      stop("If data is not defined, x.min, x.max, y.min and y.max must be.")
    }
    data <- data.frame(long = c(x.min, x.max), lat = c(y.min,
                                                       y.max))
  }
  if (any(class(data) %in% "sf")) {
    xmin <- sf::st_bbox(data)["xmin"]
    xmax <- sf::st_bbox(data)["xmax"]
    ymin <- sf::st_bbox(data)["ymin"]
    ymax <- sf::st_bbox(data)["ymax"]
    scale.x <- (xmax - xmin) * scale
    scale.y <- (ymax - ymin) * scale
  }
  else {
    xmin <- min(data$long)
    xmax <- max(data$long)
    ymin <- min(data$lat)
    ymax <- max(data$lat)
    scale.x <- (xmax - xmin) * scale
    scale.y <- (ymax - ymin) * scale
  }
  if (location == "bottomleft") {
    if (is.null(anchor)) {
      x.min <- xmin
      y.min <- ymin
    }
    else {
      x.min <- anchor["x"]
      y.min <- anchor["y"]
    }
    x.max <- x.min + scale.x
    y.max <- y.min + scale.y
  }
  if (location == "bottomright") {
    if (is.null(anchor)) {
      x.max <- xmax
      y.min <- ymin
    }
    else {
      x.max <- anchor["x"]
      y.min <- anchor["y"]
    }
    x.min <- x.max - scale.x
    y.max <- y.min + scale.y
  }
  if (location == "topleft") {
    if (is.null(anchor)) {
      x.min <- xmin
      y.max <- ymax
    }
    else {
      x.min <- anchor["x"]
      y.max <- anchor["y"]
    }
    x.max <- x.min + scale.x
    y.min <- y.max - scale.y
  }
  if (location == "topright") {
    if (is.null(anchor)) {
      x.max <- xmax
      y.max <- ymax
    }
    else {
      x.max <- anchor["x"]
      y.max <- anchor["y"]
    }
    x.min <- x.max - scale.x
    y.min <- y.max - scale.y
  }
  symbol <- sprintf("%02.f", symbol)
  symbol <- png::readPNG(paste0(system.file("symbols", package = "emu"),
                                "/", symbol, ".png"))
  symbol <- grid::rasterGrob(symbol, interpolate = TRUE)
  return(annotation_custom(symbol, xmin = x.min, xmax = x.max,
                           ymin = y.min, ymax = y.max))
}