1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
|
% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/plot.shapes.R
\name{shapes}
\alias{shapes}
\alias{igraph.vertex.shapes}
\alias{shape_noclip}
\alias{shape_noplot}
\alias{add_shape}
\title{Various vertex shapes when plotting igraph graphs}
\usage{
shapes(shape = NULL)
shape_noclip(coords, el, params, end = c("both", "from", "to"))
shape_noplot(coords, v = NULL, params)
add_shape(shape, clip = shape_noclip, plot = shape_noplot, parameters = list())
}
\arguments{
\item{shape}{Character scalar, name of a vertex shape. If it is
\code{NULL} for \code{shapes()}, then the names of all defined
vertex shapes are returned.}
\item{coords, el, params, end, v}{See parameters of the clipping/plotting
functions below.}
\item{clip}{An R function object, the clipping function.}
\item{plot}{An R function object, the plotting function.}
\item{parameters}{Named list, additional plot/vertex/edge
parameters. The element named define the new parameters, and the
elements themselves define their default values.
Vertex parameters should have a prefix
\sQuote{\code{vertex.}}, edge parameters a prefix
\sQuote{\code{edge.}}. Other general plotting parameters should have
a prefix \sQuote{\code{plot.}}. See Details below.}
}
\value{
\code{shapes()} returns a character vector if the
\code{shape} argument is \code{NULL}. It returns a named list with
entries named \sQuote{clip} and \sQuote{plot}, both of them R
functions.
\code{add_shape()} returns \code{TRUE}, invisibly.
\code{shape_noclip()} returns the appropriate columns of its
\code{coords} argument.
}
\description{
Starting from version 0.5.1 igraph supports different
vertex shapes when plotting graphs.
}
\details{
In igraph a vertex shape is defined by two functions: 1) provides
information about the size of the shape for clipping the edges and 2)
plots the shape if requested. These functions are called \dQuote{shape
functions} in the rest of this manual page. The first one is the
clipping function and the second is the plotting function.
The clipping function has the following arguments:
\describe{
\item{coords}{A matrix with four columns, it contains the
coordinates of the vertices for the edge list supplied in the
\code{el} argument.}
\item{el}{A matrix with two columns, the edges of which some end
points will be clipped. It should have the same number of rows as
\code{coords}.}
\item{params}{This is a function object that can be called to query
vertex/edge/plot graphical parameters. The first argument of the
function is \dQuote{\code{vertex}}, \dQuote{\code{edge}} or
\dQuote{\code{plot}} to decide the type of the parameter, the
second is a character string giving the name of the
parameter. E.g.
\preformatted{
params("vertex", "size")
}
}
\item{end}{Character string, it gives which end points will be
used. Possible values are \dQuote{\code{both}},
\dQuote{\code{from}} and \dQuote{\code{to}}. If
\dQuote{\code{from}} the function is expected to clip the
first column in the \code{el} edge list, \dQuote{\code{to}}
selects the second column, \dQuote{\code{both}} selects both.}
}
The clipping function should return a matrix
with the same number of rows as the \code{el} arguments.
If \code{end} is \code{both} then the matrix must have four
columns, otherwise two. The matrix contains the modified coordinates,
with the clipping applied.
The plotting function has the following arguments:
\describe{
\item{coords}{The coordinates of the vertices, a matrix with two
columns.}
\item{v}{The ids of the vertices to plot. It should match the number
of rows in the \code{coords} argument.}
\item{params}{The same as for the clipping function, see above.}
}
The return value of the plotting function is not used.
\code{shapes()} can be used to list the names of all installed
vertex shapes, by calling it without arguments, or setting the
\code{shape} argument to \code{NULL}. If a shape name is given, then
the clipping and plotting functions of that shape are returned in a
named list.
\code{add_shape()} can be used to add new vertex shapes to
igraph. For this one must give the clipping and plotting functions of
the new shape. It is also possible to list the plot/vertex/edge
parameters, in the \code{parameters} argument, that the clipping
and/or plotting functions can make use of. An example would be a
generic regular polygon shape, which can have a parameter for the
number of sides.
\code{shape_noclip()} is a very simple clipping function that the
user can use in their own shape definitions. It does no clipping, the
edges will be drawn exactly until the listed vertex position
coordinates.
\code{shape_noplot()} is a very simple (and probably not very
useful) plotting function, that does not plot anything.
}
\examples{
# all vertex shapes, minus "raster", that might not be available
shapes <- setdiff(shapes(), "")
g <- make_ring(length(shapes))
set.seed(42)
plot(g,
vertex.shape = shapes, vertex.label = shapes, vertex.label.dist = 1,
vertex.size = 15, vertex.size2 = 15,
vertex.pie = lapply(shapes, function(x) if (x == "pie") 2:6 else 0),
vertex.pie.color = list(heat.colors(5))
)
# add new vertex shape, plot nothing with no clipping
add_shape("nil")
plot(g, vertex.shape = "nil")
#################################################################
# triangle vertex shape
mytriangle <- function(coords, v = NULL, params) {
vertex.color <- params("vertex", "color")
if (length(vertex.color) != 1 && !is.null(v)) {
vertex.color <- vertex.color[v]
}
vertex.size <- 1 / 200 * params("vertex", "size")
if (length(vertex.size) != 1 && !is.null(v)) {
vertex.size <- vertex.size[v]
}
symbols(
x = coords[, 1], y = coords[, 2], bg = vertex.color,
stars = cbind(vertex.size, vertex.size, vertex.size),
add = TRUE, inches = FALSE
)
}
# clips as a circle
add_shape("triangle",
clip = shapes("circle")$clip,
plot = mytriangle
)
plot(g,
vertex.shape = "triangle", vertex.color = rainbow(vcount(g)),
vertex.size = seq(10, 20, length.out = vcount(g))
)
#################################################################
# generic star vertex shape, with a parameter for number of rays
mystar <- function(coords, v = NULL, params) {
vertex.color <- params("vertex", "color")
if (length(vertex.color) != 1 && !is.null(v)) {
vertex.color <- vertex.color[v]
}
vertex.size <- 1 / 200 * params("vertex", "size")
if (length(vertex.size) != 1 && !is.null(v)) {
vertex.size <- vertex.size[v]
}
norays <- params("vertex", "norays")
if (length(norays) != 1 && !is.null(v)) {
norays <- norays[v]
}
mapply(coords[, 1], coords[, 2], vertex.color, vertex.size, norays,
FUN = function(x, y, bg, size, nor) {
symbols(
x = x, y = y, bg = bg,
stars = matrix(c(size, size / 2), nrow = 1, ncol = nor * 2),
add = TRUE, inches = FALSE
)
}
)
}
# no clipping, edges will be below the vertices anyway
add_shape("star",
clip = shape_noclip,
plot = mystar, parameters = list(vertex.norays = 5)
)
plot(g,
vertex.shape = "star", vertex.color = rainbow(vcount(g)),
vertex.size = seq(10, 20, length.out = vcount(g))
)
plot(g,
vertex.shape = "star", vertex.color = rainbow(vcount(g)),
vertex.size = seq(10, 20, length.out = vcount(g)),
vertex.norays = rep(4:8, length.out = vcount(g))
)
}
\concept{plot.shapes}
|
