如何用 geom_rect 环绕 ggplot2 中的极坐标？

Question

我在切断极坐标对象的边界时遇到问题。我试图用一个显示所有测量角度的标准偏差的边界矩形绘制平均角度。但是，由于圆坐标的性质，我运行在 sd 超出极坐标限制的地方遇到了麻烦，我无法让它出现。我已阅读，但出于各种原因，我需要将此数据置于极坐标系中，因此我未能成功将该问题的 geom_arc_bar 解决方案应用于我的问题。

这是数据的一个子集：

test <- structure(
  list(group = structure(1:4, .Label = c("1", "2", "3", "4"),class = "factor"), 
       mang = c(100.346364791691, 61.6459563812475, -93.4372656495579, -150.308914571739), 
       mdisp = c(22.1760257078993, 16.1971728831951, 13.7224045052927, 16.3229969619169), 
       sd = c(88.7601477929364, 115.305326107927, 89.1303441207914, 75.4004747324955)), 
  row.names = c(NA, -4L),
  class = c("tbl_df", "tbl", "data.frame"), 
  .Names = c("group", "mang", "mdisp", "sd"))

代码：

library(tidyverse)
ggplot(test)+
  geom_rect(aes(xmin = mang - sd, xmax = mang + sd, ymin = 0,ymax = mdisp, fill = group))+
  geom_segment(aes(x = mang, y = 0, xend = mang, yend = mdisp))+
  scale_x_continuous(breaks = c(-90, 0, 90, 180, 270, 360), limits = c(-180, 180))+
  coord_polar(start = 2*pi, direction = -1)+
  facet_grid(~group)+
  ggtitle("polar plots with sd")

给出这张图：

如果我注释掉设置 x 比例 #scale_x_continuous(breaks=c(-90,0,90, 180, 270, 360),limits=c(-180, 180)) 的行，这些矩形将出现在我希望它们出现的位置，如图中所示，但比例是错误的：

如何让比例尺和边界矩形出现在同一个图上？

Answer 1

一种方法是自己计算环绕量并定义单独的矩形。例如：

test2 <- test %>%
  mutate(xmin = mang - sd,
         xmax = mang + sd) %>%
  mutate(xmin1 = pmax(xmin, -180),
         xmax1 = pmin(xmax, 180),
         xmin2 = ifelse(xmin < -180, 2 * 180 + xmin, -180),
         xmax2 = ifelse(xmax > 180, 2 * -180 + xmax, 180))

> test2
# A tibble: 4 x 10
  group   mang mdisp    sd   xmin    xmax  xmin1   xmax1 xmin2 xmax2
  <fct>  <dbl> <dbl> <dbl>  <dbl>   <dbl>  <dbl>   <dbl> <dbl> <dbl>
1 1      100.   22.2  88.8   11.6  189.     11.6  180    -180  -171.
2 2       61.6  16.2 115.   -53.7  177.    -53.7  177.   -180   180 
3 3      -93.4  13.7  89.1 -183.    -4.31 -180     -4.31  177.  180 
4 4     -150.   16.3  75.4 -226.   -74.9  -180    -74.9   134.  180

剧情：

ggplot(test2) +
  geom_rect(aes(xmin = xmin1, xmax = xmax1, ymin = 0, ymax = mdisp, fill = group)) +
  geom_rect(aes(xmin = xmin2, xmax = xmax2, ymin = 0, ymax = mdisp, fill = group)) +
  geom_segment(aes(x = mang, y = 0, xend = mang, yend = mdisp)) +
  scale_x_continuous(breaks = seq(-90, 180, 90), limits = c(-180, 180)) +
  coord_polar(start = 2 * pi, direction = -1) +
  facet_grid(~ group)

Answer 2

通过结合我之前的答案和 Z.lin 给出的解决方案，我最终得到了这些图的一个不优雅但准确的版本。可能有更好的方法，但我的实际数据中没有那么多类别，所以像这样手动完成是合理的。

test3<-filter(test2, group!="2") # filter out the one that doesn't work

ggplot(test)+
  geom_rect(aes(xmin = mang - sd, xmax = mang + sd, ymin = 0,ymax = mdisp))+
  geom_rect(data=test3, aes(xmin = xmin1, xmax = xmax1, ymin = 0, ymax = mdisp)) +
  geom_rect(data=test3, aes(xmin = xmin2, xmax = xmax2, ymin = 0, ymax = mdisp)) +
  geom_segment(aes(x = mang, y = 0, xend = mang, yend = mdisp), color=group)+
  scale_x_continuous(breaks = c(-90, 0, 90, 180, 270, 360), limits = c(-180, 180))+
  coord_polar(start = 2*pi, direction = -1)+
  facet_grid(~group)+
  ggtitle("polar plots with sd")

这给了我这个数字，这就是我用正确的矩形寻找的数字

谢谢。

Answer 3

一个更通用的解决方案，不排除第 2 组。它是答案 1 的更正版本。可以使用以下函数进行正确的包装。

wrap_polar_seg <- function(x, w) {
  a1 = x-w/2
  a2 = x+w/2
  u = matrix(nrow=length(x),ncol=5)
  u[,5] = ifelse(a1 < 0, ifelse(a1 > -180 & a2 > -180, 0,1), 
                         ifelse(a2 < 180 & a2 < 180,0,2)) 
  u[,1] = ifelse(u[,5] == 2,a1,     ifelse(u[,5]==1,360+a1,a1))
  u[,2] = ifelse(u[,5] == 2,180,    ifelse(u[,5]==1,180,   a2))
  u[,3] = ifelse(u[,5] == 2,a2-360, ifelse(u[,5]==1,a2,    a1))
  u[,4] = ifelse(u[,5] == 2,-180,   ifelse(u[,5]==1,-180,  a2))
  u
}

将此代码应用于当前问题

test3 = test
k = wrap_polar_seg(test$mang,test$sd*2)
test3$xmin1 = k[,1]
test3$xmax1 = k[,2]
test3$xmin2 = k[,3]
test3$xmax2 = k[,4]


ggplot(test3) +
  geom_rect(aes(xmin = xmin1, xmax = xmax1, ymin = 0, ymax = mdisp), fill = "gray") +
  geom_rect(aes(xmin = xmin2, xmax = xmax2, ymin = 0, ymax = mdisp), fill = "gray") +
  geom_segment(aes(x = mang, y = 0, xend = mang, yend = mdisp,color=group),size=2) +
  scale_x_continuous(breaks = seq(-90, 180, 90), limits = c(-180, 180)) +
  coord_polar(start = 2 * pi, direction = -1) +
  facet_grid(~ group) +
  theme_bw()

结果是：

plot resulting from the code

如何用 geom_rect 环绕 ggplot2 中的极坐标？

How to wrap around the polar coordinates in ggplot2 with geom_rect?

r

ggplot2

polar-coordinates