【发布时间】：2019-08-13 10:31:08
【问题描述】：
我正在尝试为ggplot2 编写自定义stat_*，我想使用瓷砖为2D 黄土表面着色。当我start from the extension guide 时，我可以像他们一样写一个 stat_chull：
stat_chull = function(mapping = NULL, data = NULL, geom = "polygon",
position = "identity", na.rm = FALSE, show.legend = NA,
inherit.aes = TRUE, ...) {
chull = ggproto("chull", Stat,
compute_group = function(data, scales) {
data[chull(data$x, data$y), , drop = FALSE]
},
required_aes = c("x", "y")
)
layer(
stat = chull, data = data, mapping = mapping, geom = geom,
position = position, show.legend = show.legend, inherit.aes = inherit.aes,
params = list(na.rm = na.rm, ...)
)
}
这适用于简单的调用和分面包装：
ggplot(mpg, aes(x=displ, y=hwy)) +
geom_point() +
stat_chull()
# optionally + facet_wrap(~ class)
当我写我的stat_loess2d 时，我还可以可视化所有类或单个类：
stat_loess2d = function(mapping = NULL, data = NULL, geom = "tile",
position = "identity", na.rm = FALSE, show.legend = NA,
inherit.aes = TRUE, ...) {
loess2d = ggproto("loess2d", Stat,
compute_group = function(data, scales) {
dens = MASS::kde2d(data$x, data$y)
lsurf = loess(fill ~ x + y, data=data)
df = data.frame(x = rep(dens$x, length(dens$y)),
y = rep(dens$y, each=length(dens$x)),
dens = c(dens$z))
df$fill = predict(lsurf, newdata=df[c("x", "y")])
df
},
required_aes = c("x", "y", "fill")
)
layer(
stat = loess2d, data = data, mapping = mapping, geom = geom,
position = position, show.legend = show.legend, inherit.aes = inherit.aes,
params = list(na.rm = na.rm, ...)
)
}
ggplot(mpg, aes(x=displ, y=hwy, fill=year)) +
geom_point(aes(color=year)) +
stat_loess2d()
ggplot(mpg[mpg$class == "compact",], aes(x=displ, y=hwy, fill=year)) +
geom_point(aes(color=year)) +
stat_loess2d()
但是，当我尝试处理上述内容时，不再显示图块：
ggplot(mpg, aes(x=displ, y=hwy, fill=year)) +
geom_point(aes(color=year)) +
stat_loess2d() +
facet_wrap(~ class)
谁能告诉我我在这里做错了什么？
【问题讨论】：
-
您的代码给我的警告似乎与数据稀疏性有关。
-
我认为这在这里无关紧要，因为拟合/绘图适用于各个方面（拆分数据并单独绘制）但在使用
facet_wrap(...)时不起作用。