ggplot2：轴上的花括号？ [英] ggplot2: Curly braces on an axis?

问题描述

在，请务必查看括号在保存的图像中保留。

---

OP请求括号离开图。该解决方案使用 axis.ticks.length 与 axis.ticks = element_blank（）结合以允许大括号在绘图区域之外。
这个答案建立在@Pankil和@ user697473的基础上：我们将使用 pBrackets R包 - 并包含图片！

$ bx < - c（runif（10），runif b $ b $ p $ library $（$） （10）+2）
y< -c（runif（10），runif（10）+2）
the_plot < - qplot（x = x，y = y）+
scale_x_continuous（，breaks = c（.5,2.5），labels = c（Low types，High types））+
theme（axis.ticks = element_blank（），
axis .ticks.length =单位（.85，cm））


＃运行grid.locator几次获得坐标的外部
＃支架，确保
#bottom_y坐标位于灰色区域的底部。
＃退出grid.locator命令esc;在设置坐标
＃后，在grid.bracket中注释掉grid.locator（）行
the_plot
grid.locator（unit =native）
bottom_y < - 284
grid.brackets（220，bottom_y，80，bottom_y，lwd = 2，col =red）
grid.brackets（600，bottom_y，440，bottom_y，lwd = 2，col =red）

关于@ Pankil答案的简要说明：

  ##括号坐标取决于图的大小
 ##例如
 ## Pankil建议的支架坐标不能用
 ##进行以下尺寸调整：
 the_plot 
 grid.brackets（240,440,50 ，440，lwd = 2，col =red）
 grid.brackets（570，440，381，440，lwd = 2，col =red）
 ## 440似乎关闭图表... 
  

还有一些展示 pBrackets 的功能：

 ＃注意，如果反转x1和x2，则括号翻转：
 the_plot 
 grid.brackets（80，bottom_y，220，bottom_y，lwd = 2，col =red）
 grid .brackets（440，bottom_y，600，bottom_y，lwd = 2，col =red）
  

  ##垂直：
 the_plot 
 grid.brackets（235，200，235，300，lwd = 2，col =red）
 grid.brackets（445,125,445,25，lwd = 2，col =red）
  

In answering a recent visualization question I really needed braces to show a span on an axis, and I can't figure out how to do it in ggplot2. Here's the plot:

Instead of a tick mark, I'd really like the y axis label "Second letter of two-letter names" to have a brace extending from 1 to 10 (the vertical span of the red and blue second letters). But I'm not sure how to make that happen. The x axis could benefit from similar treatment.

Code is available in the linked CrossValidated question (and unnecessarily complicated for this example, so I won't show it). Instead, here's a minimal example:

library(ggplot2)
x <- c(runif(10),runif(10)+2)
y <- c(runif(10),runif(10)+2)
qplot(x=x,y=y) +
  scale_x_continuous("",breaks=c(.5,2.5),labels=c("Low types","High types") )

In this case, a brace from (0,1) for low types and from (2,3) for the high types would be ideal instead of tick marks.

I'd rather not use geom_rect because:

• The tick marks will remain
• I'd prefer braces
• It will be inside the plot instead of outside it

How would I accomplish this? The perfect answer would have:

• A nice, smooth, thin curly brace
• Drawn outside the plotting area
• Specified via a high-level argument (ideally a range-type object passed to the breaks option in scale_x_continuous)

解决方案

Update: Be sure to see this related Stackoverflow Q&A if you need to save the plot with ggsave() and have the brackets persist in the saved image.

---

The OP requested the bracket be off the plot. This solution uses axis.ticks.length in combination with axis.ticks = element_blank() to allow the brace to be outside the plotting area. This answer builds upon those of @Pankil and @user697473: we will use pBrackets R package -- and include pictures!

library(ggplot2)
library(grid)
library(pBrackets) 
x <- c(runif(10),runif(10)+2)
y <- c(runif(10),runif(10)+2)
the_plot <- qplot(x=x,y=y) +
  scale_x_continuous("",breaks=c(.5,2.5),labels=c("Low types","High types") ) +
  theme(axis.ticks = element_blank(),
        axis.ticks.length = unit(.85, "cm"))


#Run grid.locator a few times to get coordinates for the outer
#most points of the bracket, making sure the 
#bottom_y coordinate is just at the bottom of the gray area.
# to exit grid.locator hit esc; after setting coordinates
# in grid.bracket comment out grid.locator() line
the_plot
grid.locator(unit="native") 
bottom_y <- 284
grid.brackets(220, bottom_y,   80, bottom_y, lwd=2, col="red")
grid.brackets(600, bottom_y,  440, bottom_y, lwd=2, col="red")

A quick note on @Pankil's answer:

## Bracket coordinates depend on the size of the plot
## for instance,
## Pankil's suggested bracket coordinates do not work
## with the following sizing:
the_plot
grid.brackets(240, 440, 50, 440, lwd=2, col="red")
grid.brackets(570, 440, 381, 440, lwd=2, col="red")
## 440 seems to be off the graph...

And a couple more to showcase functionality of pBrackets:

#note, if you reverse the x1 and x2, the bracket flips:
the_plot
grid.brackets( 80, bottom_y, 220, bottom_y, lwd=2, col="red")
grid.brackets(440, bottom_y, 600, bottom_y, lwd=2, col="red")

## go vertical:
the_plot
grid.brackets(235, 200, 235, 300, lwd=2, col="red")
grid.brackets(445, 125, 445,  25, lwd=2, col="red")

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