View source: R/geom-arrowsegment.R
geom_arrowsegment | R Documentation |
The basic geom_arrowsegment()
is equivalent to geom_segment(arrow = arrow())
.
(It is assumed that the user wants some kind of arrow.) The extended functionality
is to allow free placement of the arrowhead anywhere along the segment, and also
multiple arrowheads, and to allow a fill aesthetic (which will only be visible for
closed arrowheads).
The function works by dividing the line up into 1 or more segment grobs, each of
which is generated by grid::arrow()
except potentially the last (the one closest
to the point (xend
, yend
)). The vector arrow_positions
, whose entries must
lie between 0 and 1, defines where each arrow segment ends, as a proportional
position along the line. If the last entry of arrow_positions
is 1, then the last
grob has an arrow; otherwise it does not.
The function is designed with the expectation that arrows point from (x
, y
) to
(xend
, yend
) but the arrows
argument will happily accept arrow(ends = "first")
or arrow(ends = "both")
if you prefer. Just remember that the final segment is
only an arrow at all if the last entry of arrow_positions
is 1.
geom_arrowsegment(
mapping = NULL,
data = NULL,
stat = "identity",
position = "identity",
...,
arrows = list(arrow()),
arrow_fills = NULL,
arrow_positions = 1,
lineend = "butt",
linejoin = "round",
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE
)
mapping |
Set of aesthetic mappings created by |
data |
The data to be displayed in this layer. There are three options: If A A |
stat |
The statistical transformation to use on the data for this
layer, either as a |
position |
Position adjustment, either as a string naming the adjustment
(e.g. |
... |
Other arguments passed on to |
arrows |
Either an arrow generated by |
arrow_fills |
A vector of fill colours for the arrowheads, behaves as
the |
arrow_positions |
A vector of distinct points on the unit interval. 0 is not
permitted but arbitrarily small values are; 1 is permitted. The default behaviour is that
arrowheads will be placed proportionally along the line connecting ( |
lineend |
Line end style (round, butt, square). |
linejoin |
Line join style (round, mitre, bevel). |
na.rm |
If |
show.legend |
logical. Should this layer be included in the legends?
|
inherit.aes |
If |
A ggproto object
library(ggplot2)
library(magrittr)
library(tidyr)
# Generate some dummy data
ten.points <- data.frame(line.no = rep(1:5, each = 2), x = runif(10), y = runif(10),
position = rep(c("start", "end"), 5))
five.segments <- ten.points %>% pivot_wider(names_from = position, values_from = c(x,y))
# Default behaviour
ggplot(five.segments) +
geom_point(data = ten.points, aes(x = x, y = y)) +
geom_arrowsegment(aes(x = x_start, xend = x_end, y = y_start, yend = y_end))
# Midpoint arrowheads
ggplot(five.segments) +
geom_point(data = ten.points, aes(x = x, y = y)) +
geom_arrowsegment(aes(x = x_start, xend = x_end, y = y_start, yend = y_end),
arrow_positions = 0.5)
# Double arrows
ggplot(five.segments) +
geom_point(data = ten.points, aes(x = x, y = y)) +
geom_arrowsegment(aes(x = x_start, xend = x_end, y = y_start, yend = y_end),
arrow_positions = c(0.25, 0.75))
# Double arrows, last arrowhead at the end point
ggplot(five.segments) +
geom_point(data = ten.points, aes(x = x, y = y)) +
geom_arrowsegment(aes(x = x_start, xend = x_end, y = y_start, yend = y_end),
arrow_positions = c(0.25, 1))
# Double arrowheads of varying appearance and position
ggplot(five.segments) +
geom_point(data = ten.points, aes(x = x, y = y)) +
geom_arrowsegment(aes(x = x_start, xend = x_end, y = y_start, yend = y_end),
arrow_positions = c(0.25, 0.75),
arrows = list(arrow(angle = 45, type = "closed"),
arrow(angle = 25, ends = "both")),
arrow_fills = "indianred")
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