geom_sankeysegment()
draws a straight line between two connected nodes,
geom_sankeyedge()
draws a ribbon between nodes following a Bezier curved path.
If you combine the edges with geom_sankeynode()
, make sure that both use the
same position
object.
Usage
GeomSankeysegment
geom_sankeysegment(
mapping = NULL,
data = NULL,
stat = "sankeyedge",
position = "sankey",
na.rm = FALSE,
show.legend = NA,
order = c("ascending", "descending", "as_is"),
width = "auto",
align = c("bottom", "top", "center", "justify"),
h_space = "auto",
v_space = 0,
nudge_x = 0,
nudge_y = 0,
split_nodes = FALSE,
split_tol = 0.001,
direction = c("forward", "backward"),
inherit.aes = TRUE,
...
)
GeomSankeyedge
geom_sankeyedge(
mapping = NULL,
data = NULL,
stat = "sankeyedge",
position = "sankey",
na.rm = FALSE,
show.legend = NA,
slope = 0.5,
ncp = 100,
width = "auto",
align = c("bottom", "top", "center", "justify"),
order = c("ascending", "descending", "as_is"),
h_space = "auto",
v_space = 0,
nudge_x = 0,
nudge_y = 0,
split_nodes = FALSE,
split_tol = 0.001,
direction = c("forward", "backward"),
inherit.aes = TRUE,
...
)
Format
An object of class GeomSankeysegment
(inherits from GeomSegment
, Geom
, ggproto
, gg
) of length 4.
An object of class GeomSankeyedge
(inherits from GeomSankeysegment
, GeomSegment
, Geom
, ggproto
, gg
) of length 7.
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.- 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.- order
A
character
indicating the method to be used for the order of stacking nodes and edges in a plot. Should be one of:ascending
(default), sorts nodes and edges from large to small (largest on top);descending
sorts nodes and edges from small to large (smallest on top);as_is
will leave the order of nodes and edges as they are indata
.- width
Width of the node (
numeric
). Whensplit_nodes
is set toTRUE
each part of the split node will have half this width. Use"auto"
to automatically determine a suitable width.- align
A
character
that indicates how the nodes across the stages are aligned. It can be any of"top"
,"bottom"
,"center"
or"justify"
.- h_space
Horizontal space between split nodes (
numeric
). This argument is ignored whensplit_nodes == FALSE
. Use"auto"
to automatically position split nodes.- v_space
Vertical space between nodes (
numeric
). When set to zero (0
), the Sankey diagram becomes an alluvial plot. Use"auto"
to automatically determine a suitable vertical space.- nudge_x, nudge_y
Horizontal and vertical adjustment to nudge items by. Can be useful for offsetting labels.
- split_nodes
A
logical
value indicating whether the source and destination nodes should be depicted as separate boxes.- split_tol
When the relative node size (resulting source and destination edges) differs more than this fraction, the node will be displayed as two separate bars.
- direction
One of
"forward"
(default) or"backward"
. When set to"backward"
the direction of the edges will be inverted. In most cases this parameter won't affect the plot. It can be helpful when you want to decorate the end of an edge (instead of the start; see examples).- 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()
.- ...
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.- slope
Slope parameter (
numeric
) for the Bezier curves used to depict the edges. Any value between 0 and 1 will work nicely. Other non-zero values will also work.- ncp
Number of control points on the Bezier curve that forms the edge. Larger numbers will result in smoother curves, but cost more computational time. Default is 100.
Value
Returns a ggplot2::layer()
which can be added to a ggplot2::ggplot()
Details
This ggplot2
layer connects between paired nodes via a Bezier curve. The width
of the curve is determined by its y
aesthetic. It will be attempted to keep the
width of the curve constant along its curved path, for the targeted graphics device.
When the aspect ratio of the graphics device is altered after the plot is generated,
the aspect ratio maybe off. In that case render the plot again.
Aesthetics
geom_sankeysegment()
and geom_sankeyedge()
understand the following
aesthetics (required aesthetics are in bold)
x
: Works for variables on a discrete scale. Might work for continuous variables but is not guaranteed. This variable is used to distinguish between stages in the Sankey diagram on the x axis.y
: A continuous variable representing the width of the edges in a Sankey diagram.group
: A discrete variable used for grouping edges to nodes in each stage. Essentially it is an identifier for the nodes.connector
: Indicates which side of an edge is reflected by the corresponding record. Should be one of"from"
or"to"
.edge_id
: A unique identifier value for each edge. This identifier is used to link specific"from"
and"to"
records in an edge (flow).fill: see
vignette("ggplot2-specs", "ggplot2")
colour: see
vignette("ggplot2-specs", "ggplot2")
linetype: see
vignette("ggplot2-specs", "ggplot2")
linewidth: see
vignette("ggplot2-specs", "ggplot2")
alpha: A variable to control the opacity of an element.
waist: A variable to control the width of an edge in between two nodes. Small values will create a hour glass shape, whereas large values will produce an apple shape.