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
|
#' Polygons
#'
#' Polygons are very similar to paths (as drawn by [geom_path()])
#' except that the start and end points are connected and the inside is
#' coloured by `fill`. The `group` aesthetic determines which cases
#' are connected together into a polygon. From R 3.6 and onwards it is possible
#' to draw polygons with holes by providing a subgroup aesthetic that
#' differentiates the outer ring points from those describing holes in the
#' polygon.
#'
#' @eval rd_aesthetics("geom", "polygon")
#' @seealso
#' [geom_path()] for an unfilled polygon,
#' [geom_ribbon()] for a polygon anchored on the x-axis
#' @export
#' @inheritParams layer
#' @inheritParams geom_point
#' @param rule Either `"evenodd"` or `"winding"`. If polygons with holes are
#' being drawn (using the `subgroup` aesthetic) this argument defines how the
#' hole coordinates are interpreted. See the examples in [grid::pathGrob()] for
#' an explanation.
#' @examples
#' # When using geom_polygon, 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
#'
#' ids <- factor(c("1.1", "2.1", "1.2", "2.2", "1.3", "2.3"))
#'
#' values <- data.frame(
#' id = ids,
#' value = c(3, 3.1, 3.1, 3.2, 3.15, 3.5)
#' )
#'
#' positions <- data.frame(
#' id = rep(ids, each = 4),
#' x = c(2, 1, 1.1, 2.2, 1, 0, 0.3, 1.1, 2.2, 1.1, 1.2, 2.5, 1.1, 0.3,
#' 0.5, 1.2, 2.5, 1.2, 1.3, 2.7, 1.2, 0.5, 0.6, 1.3),
#' y = c(-0.5, 0, 1, 0.5, 0, 0.5, 1.5, 1, 0.5, 1, 2.1, 1.7, 1, 1.5,
#' 2.2, 2.1, 1.7, 2.1, 3.2, 2.8, 2.1, 2.2, 3.3, 3.2)
#' )
#'
#' # Currently we need to manually merge the two together
#' datapoly <- merge(values, positions, by = c("id"))
#'
#' p <- ggplot(datapoly, aes(x = x, y = y)) +
#' geom_polygon(aes(fill = value, group = id))
#' p
#'
#' # Which seems like a lot of work, but then it's easy to add on
#' # other features in this coordinate system, e.g.:
#'
#' set.seed(1)
#' stream <- data.frame(
#' x = cumsum(runif(50, max = 0.1)),
#' y = cumsum(runif(50,max = 0.1))
#' )
#'
#' p + geom_line(data = stream, colour = "grey30", linewidth = 5)
#'
#' # And if the positions are in longitude and latitude, you can use
#' # coord_map to produce different map projections.
#'
#' if (packageVersion("grid") >= "3.6") {
#' # As of R version 3.6 geom_polygon() supports polygons with holes
#' # Use the subgroup aesthetic to differentiate holes from the main polygon
#'
#' holes <- do.call(rbind, lapply(split(datapoly, datapoly$id), function(df) {
#' df$x <- df$x + 0.5 * (mean(df$x) - df$x)
#' df$y <- df$y + 0.5 * (mean(df$y) - df$y)
#' df
#' }))
#' datapoly$subid <- 1L
#' holes$subid <- 2L
#' datapoly <- rbind(datapoly, holes)
#'
#' p <- ggplot(datapoly, aes(x = x, y = y)) +
#' geom_polygon(aes(fill = value, group = id, subgroup = subid))
#' p
#' }
#'
geom_polygon <- function(mapping = NULL, data = NULL,
stat = "identity", position = "identity",
rule = "evenodd",
...,
na.rm = FALSE,
show.legend = NA,
inherit.aes = TRUE) {
layer(
data = data,
mapping = mapping,
stat = stat,
geom = GeomPolygon,
position = position,
show.legend = show.legend,
inherit.aes = inherit.aes,
params = list2(
na.rm = na.rm,
rule = rule,
...
)
)
}
#' @rdname ggplot2-ggproto
#' @format NULL
#' @usage NULL
#' @export
GeomPolygon <- ggproto("GeomPolygon", Geom,
draw_panel = function(self, data, panel_params, coord, rule = "evenodd",
lineend = "butt", linejoin = "round", linemitre = 10) {
data <- check_linewidth(data, snake_class(self))
n <- nrow(data)
if (n == 1) return(zeroGrob())
munched <- coord_munch(coord, data, panel_params, is_closed = TRUE)
if (is.null(munched$subgroup)) {
# Sort by group to make sure that colors, fill, etc. come in same order
munched <- munched[order(munched$group), ]
# For gpar(), there is one entry per polygon (not one entry per point).
# We'll pull the first value from each group, and assume all these values
# are the same within each group.
first_idx <- !duplicated(munched$group)
first_rows <- munched[first_idx, ]
ggname(
"geom_polygon",
polygonGrob(
munched$x, munched$y, default.units = "native",
id = munched$group,
gp = gpar(
col = first_rows$colour,
fill = fill_alpha(first_rows$fill, first_rows$alpha),
lwd = first_rows$linewidth * .pt,
lty = first_rows$linetype,
lineend = lineend,
linejoin = linejoin,
linemitre = linemitre
)
)
)
} else {
if (getRversion() < "3.6") {
cli::cli_abort("Polygons with holes requires R 3.6 or above.")
}
# Sort by group to make sure that colors, fill, etc. come in same order
munched <- munched[order(munched$group, munched$subgroup), ]
id <- match(munched$subgroup, unique0(munched$subgroup))
# For gpar(), there is one entry per polygon (not one entry per point).
# We'll pull the first value from each group, and assume all these values
# are the same within each group.
first_idx <- !duplicated(munched$group)
first_rows <- munched[first_idx, ]
ggname(
"geom_polygon",
pathGrob(
munched$x, munched$y, default.units = "native",
id = id, pathId = munched$group,
rule = rule,
gp = gpar(
col = first_rows$colour,
fill = fill_alpha(first_rows$fill, first_rows$alpha),
lwd = first_rows$linewidth * .pt,
lty = first_rows$linetype,
lineend = lineend,
linejoin = linejoin,
linemitre = linemitre
)
)
)
}
},
default_aes = aes(colour = NA, fill = "grey20", linewidth = 0.5, linetype = 1,
alpha = NA, subgroup = NULL),
handle_na = function(data, params) {
data
},
required_aes = c("x", "y"),
draw_key = draw_key_polygon,
rename_size = TRUE
)
# Assigning pathGrob in .onLoad ensures that packages that subclass GeomPolygon
# do not install with error `possible error in 'pathGrob(munched$x, munched$y, ':
# unused argument (pathId = munched$group)` despite the fact that this is correct
# usage
pathGrob <- NULL
on_load(
if (getRversion() < as.numeric_version("3.6")) {
pathGrob <- function(..., pathId.lengths) {
grid::pathGrob(...)
}
}
)
|
