geom_segment()
draws a straight line between points (x, y) and
(xend, yend). geom_curve()
draws a curved line. See the underlying
drawing function grid::curveGrob()
for the parameters that
control the curve.
Usage
geom_segment(
mapping = NULL,
data = NULL,
stat = "identity",
position = "identity",
...,
arrow = NULL,
arrow.fill = NULL,
lineend = "butt",
linejoin = "round",
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE
)
geom_curve(
mapping = NULL,
data = NULL,
stat = "identity",
position = "identity",
...,
curvature = 0.5,
angle = 90,
ncp = 5,
arrow = NULL,
arrow.fill = NULL,
lineend = "butt",
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE
)
Arguments
- mapping
Set of aesthetic mappings created by
aes()
. If specified andinherit.aes = TRUE
(the default), it is combined with the default mapping at the top level of the plot. You must supplymapping
if there is no plot mapping.- data
The data to be displayed in this layer. There are three options:
If
NULL
, the default, the data is inherited from the plot data as specified in the call toggplot()
.A
data.frame
, or other object, will override the plot data. All objects will be fortified to produce a data frame. Seefortify()
for which variables will be created.A
function
will be called with a single argument, the plot data. The return value must be adata.frame
, and will be used as the layer data. Afunction
can be created from aformula
(e.g.~ head(.x, 10)
).- stat
The statistical transformation to use on the data for this layer, either as a
ggproto
Geom
subclass or as a string naming the stat stripped of thestat_
prefix (e.g."count"
rather than"stat_count"
)- position
Position adjustment, either as a string naming the adjustment (e.g.
"jitter"
to useposition_jitter
), or the result of a call to a position adjustment function. Use the latter if you need to change the settings of the adjustment.- ...
Other arguments passed on to
layer()
. These are often aesthetics, used to set an aesthetic to a fixed value, likecolour = "red"
orsize = 3
. They may also be parameters to the paired geom/stat.- arrow
specification for arrow heads, as created by
grid::arrow()
.- arrow.fill
fill colour to use for the arrow head (if closed).
NULL
means usecolour
aesthetic.- lineend
Line end style (round, butt, square).
- linejoin
Line join style (round, mitre, bevel).
- na.rm
If
FALSE
, the default, missing values are removed with a warning. IfTRUE
, missing values are silently removed.- show.legend
logical. Should this layer be included in the legends?
NA
, the default, includes if any aesthetics are mapped.FALSE
never includes, andTRUE
always includes. It can also be a named logical vector to finely select the aesthetics to display.- inherit.aes
If
FALSE
, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g.borders()
.- curvature
A numeric value giving the amount of curvature. Negative values produce left-hand curves, positive values produce right-hand curves, and zero produces a straight line.
- angle
A numeric value between 0 and 180, giving an amount to skew the control points of the curve. Values less than 90 skew the curve towards the start point and values greater than 90 skew the curve towards the end point.
- ncp
The number of control points used to draw the curve. More control points creates a smoother curve.
Details
Both geoms draw a single segment/curve per case. See geom_path()
if you
need to connect points across multiple cases.
Aesthetics
geom_segment()
understands the following aesthetics (required aesthetics are in bold):
x
y
xend
yend
alpha
colour
group
linetype
linewidth
Learn more about setting these aesthetics in vignette("ggplot2-specs")
.
See also
geom_path()
and geom_line()
for multi-
segment lines and paths.
geom_spoke()
for a segment parameterised by a location
(x, y), and an angle and radius.
Examples
b <- ggplot(mtcars, aes(wt, mpg)) +
geom_point()
df <- data.frame(x1 = 2.62, x2 = 3.57, y1 = 21.0, y2 = 15.0)
b +
geom_curve(aes(x = x1, y = y1, xend = x2, yend = y2, colour = "curve"), data = df) +
geom_segment(aes(x = x1, y = y1, xend = x2, yend = y2, colour = "segment"), data = df)
b + geom_curve(aes(x = x1, y = y1, xend = x2, yend = y2), data = df, curvature = -0.2)
b + geom_curve(aes(x = x1, y = y1, xend = x2, yend = y2), data = df, curvature = 1)
b + geom_curve(
aes(x = x1, y = y1, xend = x2, yend = y2),
data = df,
arrow = arrow(length = unit(0.03, "npc"))
)
if (requireNamespace('maps', quietly = TRUE)) {
ggplot(seals, aes(long, lat)) +
geom_segment(aes(xend = long + delta_long, yend = lat + delta_lat),
arrow = arrow(length = unit(0.1,"cm"))) +
borders("state")
}
# Use lineend and linejoin to change the style of the segments
df2 <- expand.grid(
lineend = c('round', 'butt', 'square'),
linejoin = c('round', 'mitre', 'bevel'),
stringsAsFactors = FALSE
)
df2 <- data.frame(df2, y = 1:9)
ggplot(df2, aes(x = 1, y = y, xend = 2, yend = y, label = paste(lineend, linejoin))) +
geom_segment(
lineend = df2$lineend, linejoin = df2$linejoin,
size = 3, arrow = arrow(length = unit(0.3, "inches"))
) +
geom_text(hjust = 'outside', nudge_x = -0.2) +
xlim(0.5, 2)
# You can also use geom_segment to recreate plot(type = "h") :
set.seed(1)
counts <- as.data.frame(table(x = rpois(100,5)))
counts$x <- as.numeric(as.character(counts$x))
with(counts, plot(x, Freq, type = "h", lwd = 10))
ggplot(counts, aes(x, Freq)) +
geom_segment(aes(xend = x, yend = 0), linewidth = 10, lineend = "butt")