R/geom_polypath.R
geom_polypath.Rd
Polygons are drawn by tracing a 'path' of linked vertices and applying rule to differentiate the inside and the outside of the area traversed. The 'evenodd' rule provides the normal expected behaviour seen in simple GIS geometry and is immune to self-intersections and the orientation of the path (clockwise or anti-clockwise). The 'winding' rule behaves differently for self-intersections depending on relative orientation of the interacting paths.
geom_polypath(
mapping = NULL,
data = NULL,
stat = "identity",
position = "identity",
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE,
rule = "winding",
...
)
Set of aesthetic mappings created by aes()
. If specified and
inherit.aes = TRUE
(the default), it is combined with the default mapping
at the top level of the plot. You must supply mapping
if there is no plot
mapping.
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 to ggplot()
.
A data.frame
, or other object, will override the plot
data. All objects will be fortified to produce a data frame. See
fortify()
for which variables will be created.
A function
will be called with a single argument,
the plot data. The return value must be a data.frame
, and
will be used as the layer data. A function
can be created
from a formula
(e.g. ~ head(.x, 10)
).
The statistical transformation to use on the data for this layer.
When using a geom_*()
function to construct a layer, the stat
argument can be used the override the default coupling between geoms and
stats. The stat
argument accepts the following:
A Stat
ggproto subclass, for example StatCount
.
A string naming the stat. To give the stat as a string, strip the
function name of the stat_
prefix. For example, to use stat_count()
,
give the stat as "count"
.
For more information and other ways to specify the stat, see the layer stat documentation.
A position adjustment to use on the data for this layer. This
can be used in various ways, including to prevent overplotting and
improving the display. The position
argument accepts the following:
The result of calling a position function, such as position_jitter()
.
This method allows for passing extra arguments to the position.
A string naming the position adjustment. To give the position as a
string, strip the function name of the position_
prefix. For example,
to use position_jitter()
, give the position as "jitter"
.
For more information and other ways to specify the position, see the layer position documentation.
If FALSE
, the default, missing values are removed with
a warning. If TRUE
, missing values are silently removed.
logical. Should this layer be included in the legends?
NA
, the default, includes if any aesthetics are mapped.
FALSE
never includes, and TRUE
always includes.
It can also be a named logical vector to finely select the aesthetics to
display.
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()
.
character value specifying the path fill mode: either "winding" or "evenodd", see polypath
Other arguments passed on to layer()
's params
argument. These
arguments broadly fall into one of 4 categories below. Notably, further
arguments to the position
argument, or aesthetics that are required
can not be passed through ...
. Unknown arguments that are not part
of the 4 categories below are ignored.
Static aesthetics that are not mapped to a scale, but are at a fixed
value and apply to the layer as a whole. For example, colour = "red"
or linewidth = 3
. The geom's documentation has an Aesthetics
section that lists the available options. The 'required' aesthetics
cannot be passed on to the params
. Please note that while passing
unmapped aesthetics as vectors is technically possible, the order and
required length is not guaranteed to be parallel to the input data.
When constructing a layer using
a stat_*()
function, the ...
argument can be used to pass on
parameters to the geom
part of the layer. An example of this is
stat_density(geom = "area", outline.type = "both")
. The geom's
documentation lists which parameters it can accept.
Inversely, when constructing a layer using a
geom_*()
function, the ...
argument can be used to pass on parameters
to the stat
part of the layer. An example of this is
geom_area(stat = "density", adjust = 0.5)
. The stat's documentation
lists which parameters it can accept.
The key_glyph
argument of layer()
may also be passed on through
...
. This can be one of the functions described as
key glyphs, to change the display of the layer in the legend.
a ggplot2 layer
See https://en.wikipedia.org/wiki/Even-odd_rule and https://en.wikipedia.org/wiki/Nonzero-rule for more details.
polypath
and pathGrob
geom_polygon
for the implementation on polygonGrob
,
geom_map
for a convenient way to tie the values and coordinates together,
geom_path
for an unfilled polygon,
geom_ribbon
for a polygon anchored on the x-axis
# When using geom_polypath, you will typically need two data frames:
# one contains the coordinates of each polygon (positions), and the
# other the values associated with each polygon (values). An id
# variable links the two together.
# Normally this would not be created manually, but by using \code{\link{fortify}}
# to generate it from the Spatial classes in the `sp` package.
## the built-in data \code{\link{home}} uses nested data frames
library(ggplot2)
ggplot(maphome) + aes(x = x_, y = y_, group = branch_, fill = factor(object_)) +
geom_polypath()
## this is the same example built from scratch
positions = data.frame(x = c(0, 0, 46, 46, 0, 7, 13, 13, 7, 7, 18, 24,
24, 18, 18, 31, 37, 37, 31, 31, 18.4, 18.4, 18.6, 18.8, 18.8,
18.6, 18.4, 31, 31, 37, 37, 31, 0, 21, 31, 37, 46, 0, 18, 18,
24, 24, 18, 18.4, 18.6, 18.8, 18.8, 18.6, 18.4, 18.4),
y = c(0, 19, 19, 0, 0, 6, 6, 13, 13, 6, 1, 1, 12, 12, 1, 4, 4, 11, 11,
4, 6.89999999999999, 7.49999999999999, 7.69999999999999, 7.49999999999999,
6.89999999999999, 6.69999999999999, 6.89999999999999, 27, 34,
34, 24, 27, 19, 32, 27, 24, 19, 19, 1, 12, 12, 1, 1, 6.89999999999999,
6.69999999999999, 6.89999999999999, 7.49999999999999, 7.69999999999999,
7.49999999999999, 6.89999999999999),
id = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L,
2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L),
group = c(1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 4L,
4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 6L, 6L, 6L, 6L, 6L, 7L,
7L, 7L, 7L, 7L, 7L, 8L, 8L, 8L, 8L, 8L, 9L, 9L, 9L, 9L, 9L, 9L, 9L))
values <- data.frame(
id = unique(positions$id),
value = c(2, 5.4, 3)
)
# manually merge the two together
datapoly <- merge(values, positions, by = c("id"))
# the entire house
(house <- ggplot(datapoly, aes(x = x, y = y)) + geom_polypath(aes(fill = value, group = group)))
# just the front wall (and chimney), with its three parts, the first of which has three holes
wall <- ggplot(datapoly[datapoly$id == 1, ], aes(x = x, y = y))
wall + geom_polypath(aes(fill = id, group = group))