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#' Hexagonal heatmap of 2d bin counts
#'
#' Divides the plane into regular hexagons, counts the number of cases in
#' each hexagon, and then (by default) maps the number of cases to the hexagon
#' fill. Hexagon bins avoid the visual artefacts sometimes generated by
#' the very regular alignment of [geom_bin_2d()].
#'
#' @eval rd_aesthetics("geom", "hex")
#' @seealso [stat_bin_2d()] for rectangular binning
#' @param geom,stat Override the default connection between `geom_hex()` and
#' `stat_bin_hex()`. For more information about overriding these connections,
#' see how the [stat][layer_stats] and [geom][layer_geoms] arguments work.
#' @export
#' @inheritParams layer
#' @inheritParams geom_point
#' @export
#' @examples
#' d <- ggplot(diamonds, aes(carat, price))
#' d + geom_hex()
#'
#' \donttest{
#' # You can control the size of the bins by specifying the number of
#' # bins in each direction:
#' d + geom_hex(bins = 10)
#' d + geom_hex(bins = 30)
#'
#' # Or by specifying the width of the bins
#' d + geom_hex(binwidth = c(1, 1000))
#' d + geom_hex(binwidth = c(.1, 500))
#' }
geom_hex <- function(mapping = NULL, data = NULL,
stat = "binhex", position = "identity",
...,
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE) {
layer(
data = data,
mapping = mapping,
stat = stat,
geom = GeomHex,
position = position,
show.legend = show.legend,
inherit.aes = inherit.aes,
params = list2(
na.rm = na.rm,
...
)
)
}
#' @rdname ggplot2-ggproto
#' @format NULL
#' @usage NULL
#' @export
GeomHex <- ggproto("GeomHex", Geom,
draw_group = function(self, data, panel_params, coord, lineend = "butt",
linejoin = "mitre", linemitre = 10) {
data <- check_linewidth(data, snake_class(self))
if (empty(data)) {
return(zeroGrob())
}
# Get hex sizes
if (!is.null(data$width)) {
dx <- data$width[1] / 2
} else {
dx <- resolution(data$x, FALSE, TRUE)
}
# Adjust for difference in width and height of regular hexagon. 1.15 adjusts
# for the effect of the overlapping range in y-direction on the resolution
# calculation
if (!is.null(data$height)) {
dy <- data$height[1] / sqrt(3) / 2
} else {
dy <- resolution(data$y, FALSE, TRUE) / sqrt(3) / 2 * 1.15
}
hexC <- hexbin::hexcoords(dx, dy, n = 1)
n <- nrow(data)
hexdata <- data[rep(seq_len(n), each = 6), c("x", "y")]
hexdata$x <- rep.int(hexC$x, n) + hexdata$x
hexdata$y <- rep.int(hexC$y, n) + hexdata$y
coords <- coord$transform(hexdata, panel_params)
ggname("geom_hex", polygonGrob(
coords$x, coords$y,
gp = gpar(
col = data$colour,
fill = fill_alpha(data$fill, data$alpha),
lwd = data$linewidth * .pt,
lty = data$linetype,
lineend = lineend,
linejoin = linejoin,
linemitre = linemitre
),
default.units = "native",
id.lengths = rep.int(6, n)
))
},
required_aes = c("x", "y"),
default_aes = aes(
colour = NA,
fill = "grey50",
linewidth = 0.5,
linetype = 1,
alpha = NA
),
draw_key = draw_key_polygon,
rename_size = TRUE
)
# Draw hexagon grob
# Modified from code by Nicholas Lewin-Koh and Martin Maechler
#
# @param x positions of hex centres
# @param y positions
# @param size vector of hex sizes
# @param gp graphical parameters
# @keyword internal
#
# THIS IS NO LONGER USED BUT LEFT IF CODE SOMEWHERE ELSE RELIES ON IT
hexGrob <- function(x, y, size = rep(1, length(x)), gp = gpar()) {
if (length(y) != length(x)) {
cli::cli_abort("{.arg x} and {.arg y} must have the same length")
}
dx <- resolution(x, FALSE)
dy <- resolution(y, FALSE) / sqrt(3) / 2 * 1.15
hexC <- hexbin::hexcoords(dx, dy, n = 1)
n <- length(x)
polygonGrob(
x = rep.int(hexC$x, n) * rep(size, each = 6) + rep(x, each = 6),
y = rep.int(hexC$y, n) * rep(size, each = 6) + rep(y, each = 6),
default.units = "native",
id.lengths = rep(6, n), gp = gp
)
}
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