如何在 ggplot 上方直接绘制与下图对齐的图像？

Question

我正在尝试在已存在的

ggplot

对象的顶部插入图像。下面是我的最终目标的示例，使用图像处理器创建。

...这是一些复制排列的 ggplot 方面的代码。

library(tidyverse)

proportion<-data.frame(group=c(rep("A",10),
                  rep("B",10),
                  rep("C",10)),
           num=c(rnorm(20,mean=0.45,sd=0.05),
                rnorm(20,mean=0.55,sd=0.05),
                rnorm(20,mean=0.5,sd=0.05)))

proportion %>%
  ggplot(aes(x=num,y=group)) +
  geom_boxplot(width=0.5)+
  coord_cartesian(xlim=c(0,1))+
  labs(x="measurement (as percent of total length)",y="group")+
  geom_vline(xintercept=c(0,1))

该图表应该以身体长度的百分比来表示鱼身体上某物的位置，并且将轮廓放置在 y 轴正上方可以让读者更直观地了解图表所测量的内容。轮廓的 xmin 和 xmax 需要与图形 x 轴上的 c(0,1) 对齐，以便进行比较。

此数据应该用于编织为 .html 的 RMarkdown 文件中的数据报告，因此不可能简单地从 R 导出 ggplot 并在图像处理器中对其进行编辑。我无法找出在 R 中实现此目的的最佳方法。我尝试使用

cowplot

和

magick

包，但发现如果 y 轴是离散的，则很难在图表上放置图像多变的。我认为这可以通过使用

gridExtra

并调用附加视口来实现，但我不知道如何使图像与下图正确对齐。有谁知道如何实现这一点？

Answer 1

执行此操作的一个可靠方法是将鱼形状加载到光栅中，转换为多边形，然后标准化坐标，以便它们恰好达到 x 轴上的 0 和 1 之间。然后，您可以在 ggplot 中将鱼绘制为多边形，并使用

patchwork

将两个图缝合在一起 - 这将自动对齐鱼和比例。拼凑图也可以很好地与 R Markdown 配合使用。

library(ggplot2)
library(patchwork)

p1 <- ggplot(fish, aes(X, Y)) +
  geom_polygon(fill = "steelblue", alpha = 0.5) +
  geom_vline(xintercept = c(0, 1)) +
  scale_x_continuous(expand = c(0, 0)) +
  theme_void()

p2 <- proportion %>%
  ggplot(aes(x = num,y = group)) +
  geom_boxplot(width = 0.5, fill = "lightblue", alpha = 0.5) +
  coord_cartesian(xlim = c(0, 1)) +
  scale_x_continuous(expand = c(0, 0)) +
  labs(x = "measurement (as percent of total length)", y = "group") +
  geom_vline(xintercept = c(0, 1)) +
  theme_classic(base_size = 16) +
  theme(axis.line.y = element_blank())

p1 / p2 + plot_layout(heights = 1:2) & theme(plot.margin = margin(0, 20, 0, 0))

---

xy 坐标为鱼形状

fish <- structure(list(X = c(286, 289, 289, 290, 290, 291, 291, 290, 
290, 291, 291, 295, 295, 297, 297, 298, 298, 299, 299, 300, 300, 
301, 301, 302, 302, 303, 303, 304, 304, 305, 305, 306, 306, 307, 
307, 308, 308, 309, 309, 310, 310, 311, 311, 312, 312, 313, 313, 
312, 312, 313, 313, 316, 316, 318, 318, 319, 319, 320, 320, 321, 
321, 322, 322, 323, 323, 324, 324, 325, 325, 327, 327, 328, 328, 
329, 329, 330, 330, 331, 331, 332, 332, 333, 333, 334, 334, 335, 
335, 336, 336, 335, 335, 333, 333, 330, 330, 326, 326, 323, 323, 
320, 320, 316, 316, 322, 322, 328, 328, 335, 335, 340, 340, 347, 
347, 353, 353, 359, 359, 366, 366, 372, 372, 379, 379, 387, 387, 
393, 393, 402, 402, 409, 409, 417, 417, 421, 421, 427, 427, 432, 
432, 436, 436, 440, 440, 444, 444, 450, 450, 452, 452, 456, 456, 
458, 458, 459, 459, 460, 460, 461, 461, 462, 462, 461, 461, 460, 
460, 459, 459, 457, 457, 454, 454, 451, 451, 453, 453, 481, 481, 
488, 488, 492, 492, 494, 494, 497, 497, 498, 498, 500, 500, 501, 
501, 503, 503, 505, 505, 506, 506, 508, 508, 509, 509, 510, 510, 
512, 512, 514, 514, 516, 516, 518, 518, 520, 520, 521, 521, 523, 
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555, 558, 558, 574, 574, 575, 575, 574, 574, 575, 575, 576, 576, 
575, 575, 576, 576, 575, 575, 574, 574, 575, 575, 574, 574, 573, 
573, 572, 572, 571, 571, 570, 570, 569, 569, 568, 568, 567, 567, 
568, 568, 569, 569, 570, 570, 571, 571, 572, 572, 573, 573, 574, 
574, 575, 575, 576, 576, 577, 577, 578, 578, 579, 579, 580, 580, 
581, 581, 576, 576, 571, 571, 566, 566, 555, 555, 550, 550, 545, 
545, 541, 541, 537, 537, 534, 534, 530, 530, 527, 527, 524, 524, 
521, 521, 519, 519, 516, 516, 513, 513, 510, 510, 508, 508, 505, 
505, 502, 502, 498, 498, 495, 495, 491, 491, 486, 486, 481, 481, 
465, 465, 457, 457, 451, 451, 446, 446, 442, 442, 443, 443, 446, 
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430, 430, 428, 428, 425, 425, 423, 423, 421, 421, 419, 419, 417, 
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381, 381, 379, 379, 377, 377, 373, 373, 348, 348, 340, 340, 329, 
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285, 284, 284, 283, 283, 281, 281, 279, 279, 278, 278, 277, 277, 
276, 276, 275, 275, 273, 273, 272, 272, 271, 271, 270, 270, 266, 
266, 265, 265, 263, 263, 262, 262, 261, 261, 260, 260, 259, 259, 
258, 258, 257, 257, 256, 256, 255, 255, 253, 253, 251, 251, 240, 
240, 233, 233, 207, 207, 199, 199, 190, 190, 181, 181, 174, 174, 
166, 166, 160, 160, 154, 154, 153, 153, 152, 152, 151, 151, 147, 
147, 144, 144, 142, 142, 141, 141, 140, 140, 139, 139, 138, 138, 
137, 137, 136, 136, 135, 135, 134, 134, 133, 133, 132, 132, 131, 
131, 130, 130, 129, 129, 128, 128, 127, 127, 126, 126, 125, 125, 
124, 124, 123, 123, 122, 122, 121, 121, 120, 120, 119, 119, 115, 
115, 111, 111, 108, 108, 104, 104, 100, 100, 96, 96, 92, 92, 
88, 88, 84, 84, 80, 80, 76, 76, 72, 72, 68, 68, 65, 65, 60, 60, 
56, 56, 52, 52, 48, 48, 44, 44, 39, 39, 35, 35, 31, 31, 28, 28, 
24, 24, 21, 21, 18, 18, 16, 16, 13, 13, 11, 11, 9, 9, 8, 8, 6, 
6, 5, 5, 4, 4, 3, 3, 2, 2, 1, 1, 0, 0, 1, 1, 13, 13, 11, 11, 
9, 9, 6, 6, 4, 4, 3, 3, 2, 2, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 
6, 8, 8, 9, 9, 10, 10, 11, 11, 12, 12, 14, 14, 15, 15, 17, 17, 
18, 18, 20, 20, 22, 22, 25, 25, 27, 27, 30, 30, 33, 33, 35, 35, 
38, 38, 41, 41, 44, 44, 47, 47, 50, 50, 53, 53, 56, 56, 59, 59, 
65, 65, 67, 67, 70, 70, 74, 74, 77, 77, 81, 81, 84, 84, 87, 87, 
91, 91, 94, 94, 98, 98, 103, 103, 107, 107, 113, 113, 118, 118, 
124, 124, 130, 130, 136, 136, 144, 144, 152, 152, 160, 160, 171, 
171, 199, 199, 201, 201, 202, 202, 221, 221, 226, 226, 228, 228, 
229, 229, 230, 230, 231, 231, 232, 232, 233, 233, 234, 234, 235, 
235, 236, 236, 237, 237, 238, 238, 239, 239, 240, 240, 241, 241, 
242, 242, 243, 243, 244, 244, 245, 245, 246, 246, 247, 247, 248, 
248, 249, 249, 250, 250, 251, 251, 252, 252, 253, 253, 254, 254, 
255, 255, 257, 257, 258, 258, 259, 259, 260, 260, 261, 261, 263, 
263, 264, 264, 265, 265, 267, 267, 268, 268, 269, 269, 271, 271, 
272, 272, 274, 274, 275, 275, 277, 277, 278, 278, 280, 280, 281, 
281, 283, 283, 284, 284, 286, 286), Y = c(210, 210, 209, 209, 
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198, 197, 197, 195, 195, 194, 194, 193, 193, 192, 192, 190, 190, 
189, 189, 188, 188, 187, 187, 185, 185, 184, 184, 182, 182, 181, 
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173, 173, 172, 172, 171, 171, 170, 170, 169, 169, 168, 168, 167, 
167, 166, 166, 165, 165, 164, 164, 163, 163, 162, 162, 161, 161, 
159, 159, 158, 158, 156, 156, 154, 154, 153, 153, 152, 152, 151, 
151, 150, 150, 149, 149, 148, 148, 146, 146, 145, 145, 144, 144, 
143, 143, 142, 142, 141, 141, 140, 140, 139, 139, 138, 138, 137, 
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132, 132, 133, 133, 134, 134, 135, 135, 136, 136, 137, 137, 138, 
138, 137, 137, 136, 136, 135, 135, 134, 134, 133, 133, 132, 132, 
130, 130, 129, 129, 128, 128, 127, 127, 126, 126, 125, 125, 124, 
124, 123, 123, 124, 124, 125, 125, 126, 126, 127, 127, 128, 128, 
129, 129, 130, 130, 131, 131, 132, 132, 133, 133, 134, 134, 135, 
135, 136, 136, 137, 137, 138, 138, 139, 139, 140, 140, 141, 141, 
142, 142, 143, 143, 144, 144, 145, 145, 146, 146, 147, 147, 148, 
148, 149, 149, 150, 150, 151, 151, 152, 152, 153, 153, 154, 154, 
155, 155, 156, 156, 157, 157, 158, 158, 157, 157, 155, 155, 154, 
154, 144, 144, 143, 143, 138, 138, 137, 137, 130, 130, 126, 126, 
122, 122, 118, 118, 115, 115, 113, 113, 111, 111, 109, 109, 104, 
104, 101, 101, 97, 97, 94, 94, 91, 91, 87, 87, 81, 81, 79, 79, 
78, 78, 77, 77, 75, 75, 72, 72, 69, 69, 62, 62, 58, 58, 55, 55, 
50, 50, 49, 49, 50, 50, 51, 51, 52, 52, 53, 53, 54, 54, 55, 55, 
56, 56, 57, 57, 58, 58, 59, 59, 60, 60, 61, 61, 62, 62, 63, 63, 
64, 64, 65, 65, 66, 66, 67, 67, 68, 68, 69, 69, 70, 70, 71, 71, 
72, 72, 73, 73, 72, 72, 71, 71, 70, 70, 69, 69, 67, 67, 66, 66, 
65, 65, 64, 64, 63, 63, 56, 56, 44, 44, 35, 35, 30, 30, 26, 26, 
24, 24, 21, 21, 19, 19, 18, 18, 16, 16, 15, 15, 14, 14, 13, 13, 
14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 
22, 22, 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 
30, 30, 31, 31, 32, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 37, 
38, 38, 39, 39, 40, 40, 41, 41, 42, 42, 43, 43, 44, 44, 45, 45, 
46, 46, 47, 47, 46, 46, 45, 45, 44, 44, 43, 43, 42, 42, 41, 41, 
40, 40, 39, 39, 36, 36, 32, 32, 25, 25, 24, 24, 20, 20, 14, 14, 
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36, 37, 37, 38, 38, 39, 39, 40, 40, 41, 41, 42, 42, 21, 21, 19, 
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54, 55, 55, 56, 56, 57, 57, 58, 58, 59, 59, 60, 60, 61, 61, 62, 
62, 63, 63, 64, 64, 65, 65, 66, 66, 67, 67, 68, 68, 69, 69, 70, 
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86, 87, 87, 91, 91, 92, 92, 93, 93, 94, 94, 95, 95, 96, 96, 97, 
97, 98, 98, 99, 99, 105, 105, 106, 106, 107, 107, 108, 108, 109, 
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156, 156, 157, 157, 158, 158, 157, 157, 158, 158, 159, 159, 160, 
160, 161, 161, 162, 162, 163, 163, 164, 164, 165, 165, 166, 166, 
167, 167, 168, 168, 169, 169, 170, 170, 171, 171, 172, 172, 173, 
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186, 187, 187, 188, 188, 189, 189, 190, 190, 191, 191, 192, 192, 
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199, 200, 200, 201, 201, 202, 202, 203, 203, 204, 204, 205, 205, 
206, 206, 207, 207, 208, 208, 209, 209, 210)), 
row.names = 6:968, class = "data.frame")/581