# Detect and prevent collisions.
# Powers dodging, stacking and filling.
collide_setup <- function(data, width = NULL, name, strategy,
check.width = TRUE, reverse = FALSE) {
# Determine width
if (!is.null(width)) {
# Width set manually
if (!(all(c("xmin", "xmax") %in% names(data)))) {
data$xmin <- data$x - width / 2
data$xmax <- data$x + width / 2
}
} else {
if (!(all(c("xmin", "xmax") %in% names(data)))) {
data$xmin <- data$x
data$xmax <- data$x
}
# Width determined from data, must be floating point constant
widths <- unique(data$xmax - data$xmin)
widths <- widths[!is.na(widths)]
# # Suppress warning message since it's not reliable
# if (!zero_range(range(widths))) {
# warning(name, " requires constant width: output may be incorrect",
# call. = FALSE)
# }
width <- widths[1]
}
list(data = data, width = width)
}
collide <- function(data, width = NULL, name, strategy,
..., check.width = TRUE, reverse = FALSE) {
dlist <- collide_setup(data, width, name, strategy, check.width, reverse)
data <- dlist$data
width <- dlist$width
# Reorder by x position, then on group. The default stacking order reverses
# the group in order to match the legend order.
if (reverse) {
data <- data[order(data$xmin, data$group), ]
} else {
data <- data[order(data$xmin, -data$group), ]
}
# Check for overlap
intervals <- as.numeric(t(unique(data[c("xmin", "xmax")])))
intervals <- intervals[!is.na(intervals)]
if (length(unique(intervals)) > 1 & any(diff(scale(intervals)) < -1e-6)) {
warning(name, " requires non-overlapping x intervals", call. = FALSE)
# This is where the algorithm from [L. Wilkinson. Dot plots.
# The American Statistician, 1999.] should be used
}
if (!is.null(data$ymax)) {
plyr::ddply(data, "xmin", strategy, ..., width = width)
} else if (!is.null(data$y)) {
data$ymax <- data$y
data <- plyr::ddply(data, "xmin", strategy, ..., width = width)
data$y <- data$ymax
data
} else {
stop("Neither y nor ymax defined")
}
}
# Alternate version of collide() used by position_dodge2()
collide2 <- function(data, width = NULL, name, strategy,
..., check.width = TRUE, reverse = FALSE) {
dlist <- collide_setup(data, width, name, strategy, check.width, reverse)
data <- dlist$data
width <- dlist$width
# Reorder by x position, then on group. The default stacking order is
# different than for collide() because of the order in which pos_dodge2 places
# elements
if (reverse) {
data <- data[order(data$x, -data$group), ]
} else {
data <- data[order(data$x, data$group), ]
}
pos <- match.fun(strategy)
pos(data, width, ...)
}
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