#' Horizontal violin plot.
#'
#' Horizontal version of \code{\link[ggplot2]{geom_violin}()}.
#' @inheritParams ggplot2::geom_violin
#' @inheritParams ggplot2::geom_point
#' @eval rd_aesthetics("geom", "violinh")
#' @export
geom_violinh <- function(mapping = NULL, data = NULL,
stat = "xdensity", position = "dodgev",
...,
draw_quantiles = NULL,
trim = TRUE,
scale = "area",
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE) {
layer(
data = data,
mapping = mapping,
stat = stat,
geom = GeomViolinh,
position = position,
show.legend = show.legend,
inherit.aes = inherit.aes,
params = list(
trim = trim,
scale = scale,
draw_quantiles = draw_quantiles,
na.rm = na.rm,
...
)
)
}
#' @rdname ggstance-ggproto
#' @format NULL
#' @usage NULL
#' @include legend-draw.R
#' @export
GeomViolinh <- ggproto("GeomViolinh", Geom,
setup_data = function(data, params) {
data$width <- data$width %||%
params$width %||% (resolution(data$y, FALSE) * 0.9)
# ymin, ymax, xmin, and xmax define the bounding rectangle for each group
plyr::ddply(data, "group", transform,
ymin = y - width / 2,
ymax = y + width / 2
)
},
draw_group = function(self, data, ..., draw_quantiles = NULL) {
# Find the points for the line to go all the way around
data <- transform(data,
yminv = y - violinwidth * (y - ymin),
ymaxv = y + violinwidth * (ymax - y)
)
# Make sure it's sorted properly to draw the outline
newdata <- rbind(
plyr::arrange(transform(data, y = yminv), x),
plyr::arrange(transform(data, y = ymaxv), -x)
)
# Close the polygon: set first and last point the same
# Needed for coord_polar and such
newdata <- rbind(newdata, newdata[1,])
# Draw quantiles if requested, so long as there is non-zero y range
if (length(draw_quantiles) > 0 & !scales::zero_range(range(data$x))) {
stopifnot(all(draw_quantiles >= 0), all(draw_quantiles <= 1))
# Compute the quantile segments and combine with existing aesthetics
quantiles <- create_quantile_segment_frame(data, draw_quantiles)
aesthetics <- data[
rep(1, nrow(quantiles)),
setdiff(names(data), c("x", "y")),
drop = FALSE
]
aesthetics$alpha <- rep(1, nrow(quantiles))
both <- cbind(quantiles, aesthetics)
quantile_grob <- GeomPath$draw_panel(both, ...)
ggname("geom_violin", grobTree(
GeomPolygon$draw_panel(newdata, ...),
quantile_grob)
)
} else {
ggname("geom_violin", GeomPolygon$draw_panel(newdata, ...))
}
},
draw_key = draw_key_polygon,
default_aes = aes(weight = 1, colour = "grey20", fill = "white", size = 0.5,
alpha = NA, linetype = "solid"),
required_aes = c("x", "y")
)
# Returns a data.frame with info needed to draw quantile segments.
create_quantile_segment_frame <- function(data, draw_quantiles) {
dens <- cumsum(data$density) / sum(data$density)
ecdf <- stats::approxfun(dens, data$x)
xs <- ecdf(draw_quantiles) # these are all the x-values for quantiles
# Get the violin bounds for the requested quantiles.
violin.yminvs <- (stats::approxfun(data$x, data$yminv))(xs)
violin.ymaxvs <- (stats::approxfun(data$x, data$ymaxv))(xs)
# We have two rows per segment drawn. Each segment gets its own group.
data.frame(
x = rep(xs, each = 2),
y = interleave(violin.yminvs, violin.ymaxvs),
group = rep(xs, each = 2)
)
}
# Interleave (or zip) multiple units into one vector
interleave <- function(...) UseMethod("interleave")
#' @export
interleave.unit <- function(...) {
do.call("unit.c", do.call("interleave.default", plyr::llply(list(...), as.list)))
}
#' @export
interleave.default <- function(...) {
vectors <- list(...)
# Check lengths
lengths <- unique(setdiff(plyr::laply(vectors, length), 1))
if (length(lengths) == 0) lengths <- 1
stopifnot(length(lengths) <= 1)
# Replicate elements of length one up to correct length
singletons <- plyr::laply(vectors, length) == 1
vectors[singletons] <- plyr::llply(vectors[singletons], rep, lengths)
# Interleave vectors
n <- lengths
p <- length(vectors)
interleave <- rep(1:n, each = p) + seq(0, p - 1) * n
unlist(vectors, recursive = FALSE)[interleave]
}
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