Extra Coordinate Systems, 'Geoms', Statistical Transformations, Scales and Fonts for 'ggplot2'
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# Grob for axes
#
# @param position of ticks
# @param labels at ticks
# @param position of axis (top, bottom, left or right)
# @param range of data values
guide_axis <- function(at, labels, position = "right", theme) {
if (length(at) == 0)
return(zeroGrob())
at <- unit(at, "native")
position <- match.arg(position, c("top", "bottom", "right", "left"))
zero <- unit(0, "npc")
one <- unit(1, "npc")
label_render <- switch(position,
top = , bottom = "axis.text.x",
left = , right = "axis.text.y"
)
label_x <- switch(position,
top = ,
bottom = at,
right = theme$axis.ticks.length,
left = one - theme$axis.ticks.length
)
label_y <- switch(position,
top = theme$axis.ticks.length,
bottom = one - theme$axis.ticks.length,
right = ,
left = at
)
if (is.list(labels)) {
if (any(sapply(labels, is.language))) {
labels <- do.call(expression, labels)
} else {
labels <- unlist(labels)
}
}
labels <- switch(position,
top = ,
bottom = element_render(theme, label_render, labels, x = label_x, expand_y = TRUE),
right = ,
left = element_render(theme, label_render, labels, y = label_y, expand_x = TRUE))
line <- switch(position,
top = element_render(theme, "axis.line.x", c(0, 1), c(0, 0), id.lengths = 2),
bottom = element_render(theme, "axis.line.x", c(0, 1), c(1, 1), id.lengths = 2),
right = element_render(theme, "axis.line.y", c(0, 0), c(0, 1), id.lengths = 2),
left = element_render(theme, "axis.line.y", c(1, 1), c(0, 1), id.lengths = 2)
)
nticks <- length(at)
ticks <- switch(position,
top = element_render(theme, "axis.ticks.x",
x = rep(at, each = 2),
y = rep(unit.c(zero, theme$axis.ticks.length), nticks),
id.lengths = rep(2, nticks)),
bottom = element_render(theme, "axis.ticks.x",
x = rep(at, each = 2),
y = rep(unit.c(one - theme$axis.ticks.length, one), nticks),
id.lengths = rep(2, nticks)),
right = element_render(theme, "axis.ticks.y",
x = rep(unit.c(zero, theme$axis.ticks.length), nticks),
y = rep(at, each = 2),
id.lengths = rep(2, nticks)),
left = element_render(theme, "axis.ticks.y",
x = rep(unit.c(one - theme$axis.ticks.length, one), nticks),
y = rep(at, each = 2),
id.lengths = rep(2, nticks))
)
# Create the gtable for the ticks + labels
gt <- switch(position,
top = gtable_col("axis",
grobs = list(labels, ticks),
width = one,
heights = unit.c(grobHeight(labels), theme$axis.ticks.length)
),
bottom = gtable_col("axis",
grobs = list(ticks, labels),
width = one,
heights = unit.c(theme$axis.ticks.length, grobHeight(labels))
),
right = gtable_row("axis",
grobs = list(ticks, labels),
widths = unit.c(theme$axis.ticks.length, grobWidth(labels)),
height = one
),
left = gtable_row("axis",
grobs = list(labels, ticks),
widths = unit.c(grobWidth(labels), theme$axis.ticks.length),
height = one
)
)
# Viewport for justifying the axis grob
justvp <- switch(position,
top = viewport(y = 0, just = "bottom", height = gtable_height(gt)),
bottom = viewport(y = 1, just = "top", height = gtable_height(gt)),
right = viewport(x = 0, just = "left", width = gtable_width(gt)),
left = viewport(x = 1, just = "right", width = gtable_width(gt))
)
absoluteGrob(
gList(line, gt),
width = gtable_width(gt),
height = gtable_height(gt),
vp = justvp
)
}