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#' Jitter points to avoid overplotting.
#'
#' @family position adjustments
#' @param width degree of jitter in x direction. Defaults to 40\% of the
#' resolution of the data.
#' @param height degree of jitter in y direction. Defaults to 40\% of the
#' resolution of the data
#' @export
#' @examples
#' qplot(am, vs, data = mtcars)
#'
#' # Default amount of jittering will generally be too much for
#' # small datasets:
#' qplot(am, vs, data = mtcars, position = "jitter")
#' # Control the amount as follows
#' qplot(am, vs, data = mtcars, position = position_jitter(w = 0.1, h = 0.1))
#'
#' # With ggplot
#' ggplot(mtcars, aes(x = am, y = vs)) + geom_point(position = "jitter")
#' ggplot(mtcars, aes(x = am, y = vs)) + geom_point(position = position_jitter(w = 0.1, h = 0.1))
#'
#' # The default works better for large datasets, where it will
#' # take up as much space as a boxplot or a bar
#' qplot(class, hwy, data = mpg, geom = c("boxplot", "jitter"))
position_jitter <- function (width = NULL, height = NULL) {
PositionJitter$new(width = width, height = height)
}
PositionJitter <- proto(Position, {
objname <- "jitter"
adjust <- function(., data) {
if (empty(data)) return(data.frame())
check_required_aesthetics(c("x", "y"), names(data), "position_jitter")
if (is.null(.$width)) .$width <- resolution(data$x, zero = FALSE) * 0.4
if (is.null(.$height)) .$height <- resolution(data$y, zero = FALSE) * 0.4
trans_x <- NULL
trans_y <- NULL
if(.$width > 0) {
trans_x <- function(x) jitter(x, amount = .$width)
}
if(.$height > 0) {
trans_y <- function(x) jitter(x, amount = .$height)
}
transform_position(data, trans_x, trans_y)
}
})
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