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#' @include geom-map.r
NULL
#' Annotation: maps.
#'
#' @param map data frame representing a map. Most map objects can be
#' converted into the right format by using \code{\link{fortify}}
#' @param ... other arguments used to modify aesthetics
#' @export
#' @examples
#' library(maps)
#' usamap <- map_data("state")
#'
#' seal.sub <- subset(seals, long > -130 & lat < 45 & lat > 40)
#' ggplot(seal.sub, aes(x = long, y = lat)) +
#' annotation_map(usamap, fill = "NA", colour = "grey50") +
#' geom_segment(aes(xend = long + delta_long, yend = lat + delta_lat))
#'
#' seal2 <- transform(seal.sub,
#' latr = cut(lat, 2),
#' longr = cut(long, 2))
#'
#' ggplot(seal2, aes(x = long, y = lat)) +
#' annotation_map(usamap, fill = "NA", colour = "grey50") +
#' geom_segment(aes(xend = long + delta_long, yend = lat + delta_lat)) +
#' facet_grid(latr ~ longr, scales = "free", space = "free")
annotation_map <- function(map, ...) {
# Get map input into correct form
stopifnot(is.data.frame(map))
if (!is.null(map$lat)) map$y <- map$lat
if (!is.null(map$long)) map$x <- map$long
if (!is.null(map$region)) map$id <- map$region
stopifnot(all(c("x", "y", "id") %in% names(map)))
GeomAnnotationMap$new(geom_params = list(map = map, ...), data =
NULL, inherit.aes = FALSE)
}
GeomAnnotationMap <- proto(GeomMap, {
objname <- "map"
draw_groups <- function(., data, scales, coordinates, map, ...) {
# Munch, then set up id variable for polygonGrob -
# must be sequential integers
coords <- coord_munch(coordinates, map, scales)
coords$group <- coords$group %||% coords$id
grob_id <- match(coords$group, unique(coords$group))
polygonGrob(coords$x, coords$y, default.units = "native",
id = grob_id,
gp = gpar(
col = data$colour, fill = alpha(data$fill, data$alpha),
lwd = data$size * .pt))
}
required_aes <- c()
})
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