R/aes-position.R

In tidyverse/ggplot2: Create Elegant Data Visualisations Using the Grammar of Graphics

#' Position related aesthetics: x, y, xmin, xmax, ymin, ymax, xend, yend
#'
#' The following aesthetics can be used to specify the position of elements:
#' `x`, `y`, `xmin`, `xmax`, `ymin`, `ymax`, `xend`, `yend`.
#'
#' `x` and `y` define the locations of points or of positions along a line
#' or path.
#'
#' `x`, `y` and `xend`, `yend` define the starting and ending points of
#' segment and curve geometries.
#'
#' `xmin`, `xmax`, `ymin`  and `ymax` can be used to specify the position of
#' annotations and to represent rectangular areas.
#'
#' In addition, there are position aesthetics that are contextual to the
#' geometry that they're used in. These are `xintercept`, `yintercept`,
#' `xmin_final`, `ymin_final`, `xmax_final`, `ymax_final`, `xlower`, `lower`,
#' `xmiddle`, `middle`, `xupper`, `upper`, `x0` and `y0`. Many of these are used
#' and automatically computed in [`geom_boxplot()`].
#'
#' @name aes_position
#' @aliases x y xmin xmax ymin ymax xend yend
#'
#' @seealso
#' * Geoms that commonly use these aesthetics: [geom_crossbar()],
#' [geom_curve()], [geom_errorbar()], [geom_line()], [geom_linerange()],
#' [geom_path()], [geom_point()], [geom_pointrange()], [geom_rect()],
#' [geom_segment()]
#' * Scales that can be used to modify positions:
#'   [`scale_continuous()`][scale_x_continuous()],
#'   [`scale_discrete()`][scale_x_discrete()],
#'   [`scale_binned()`][scale_x_binned()],
#'   [`scale_date()`][scale_x_date()].
#' * See also [annotate()] for placing annotations.
#' @family aesthetics documentation
#' @examples
#'
#' # Generate data: means and standard errors of means for prices
#' # for each type of cut
#' dmod <- lm(price ~ cut, data = diamonds)
#' cut <- unique(diamonds$cut)
#' cuts_df <- data.frame(
#'   cut,
#'   predict(dmod, data.frame(cut), se = TRUE)[c("fit", "se.fit")]
#' )
#' ggplot(cuts_df) +
#'   aes(
#'    x = cut,
#'    y = fit,
#'    ymin = fit - se.fit,
#'    ymax = fit + se.fit,
#'    colour = cut
#'   ) +
#'   geom_pointrange()
#'
#' # Using annotate
#' p <- ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point()
#' p
#' p + annotate(
#'   "rect", xmin = 2, xmax = 3.5, ymin = 2, ymax = 25,
#'   fill = "dark grey", alpha = .5
#' )
#'
#' # Geom_segment examples
#' p + geom_segment(
#'   aes(x = 2, y = 15, xend = 2, yend = 25),
#'   arrow = arrow(length = unit(0.5, "cm"))
#' )
#' p + geom_segment(
#'   aes(x = 2, y = 15, xend = 3, yend = 15),
#'   arrow = arrow(length = unit(0.5, "cm"))
#' )
#' p + geom_segment(
#'   aes(x = 5, y = 30, xend = 3.5, yend = 25),
#'   arrow = arrow(length = unit(0.5, "cm"))
#' )
#'
#' # You can also use geom_segment() to recreate plot(type = "h")
#' # from base R:
#' set.seed(1)
#' counts <- as.data.frame(table(x = rpois(100, 5)))
#' counts$x <- as.numeric(as.character(counts$x))
#' with(counts, plot(x, Freq, type = "h", lwd = 10))
#'
#' ggplot(counts, aes(x = x, y = Freq)) +
#'   geom_segment(aes(yend = 0, xend = x), size = 10)
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