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首页 > 解决方案 > 如何在组合 ggplots 上添加线，从一个图上的点到另一个图上的点？

r - 如何在组合 ggplots 上添加线，从一个图上的点到另一个图上的点？

问题描述

为了重现性，我需要在 ggplot 中重现 InDesign 中生成的图。

在这个特定的例子中，我有两个图组合成一个复合图（我{patchwork}为此使用了包）。

然后，我需要将连接一个图上关键点的线与底部图上的相应点重叠。

这两个图是从相同的数据生成的，具有相同的 x 轴值，但不同的 y 轴值。

我在 Stack Overflow 上看到了这些示例，但是这些示例涉及跨方面绘制线，这在这里不起作用，因为我试图在单独的图中绘制线：

我尝试了几种方法，到目前为止我最接近的是：

  1. {grid}使用包添加带有 grobs 的行
  2. 使用将第二个绘图转换为 gtable{gtable}并将面板的剪辑设置为关闭，以便我可以将线条向上延伸到绘图面板之外。
  3. 将这些图再次组合成一个图像{patchwork}。

问题出现在最后一步，因为 x 轴现在不再像添加线条并将剪辑设置为关闭之前那样排列（参见代码中的示例）。

我还尝试将这些情节与ggarrange,{cowplot}和{egg}和{patchwork}最接近。

以下是我尝试创建的最佳最小表示，但仍然捕捉到我想要实现的细微差别。

library(ggplot2)
library(dplyr)
library(tidyr)
library(patchwork)
library(gtable)
library(grid)

# DATA
x <- 1:20
data <- data.frame(
  quantity = x,
  curve1 = 10 + 50*exp(-0.2 * x),
  curve2 = 5 + 50*exp(-0.5 * x),
  profit = c(seq(10, 100, by = 10),
             seq(120, -240, by = -40))
)

data_long <- data %>%
  gather(key = "variable", value = "value", -quantity)

# POINTS AND LINES
POINTS <- data.frame(
  label = c("B", "C"),
  quantity = c(5, 10),
  value = c(28.39397, 16.76676),
  profit = c(50, 100)
)

GROB <- linesGrob()

# Set maximum y-value to extend lines to outside of plot area
GROB_MAX <- 200

# BASE PLOTS
# Plot 1
p1 <- data_long %>%
  filter(variable != "profit") %>%
  ggplot(aes(x = quantity, y = value)) +
  geom_line(aes(color = variable)) +
  labs(x = "") +
  coord_cartesian(xlim = c(0, 20), ylim = c(0, 30), expand = FALSE) +
  theme(legend.justification = "top")
p1

# Plot 2
p2 <- data_long %>%
  filter(variable == "profit") %>%
  ggplot(aes(x = quantity, y = value)) +
  geom_line(color = "darkgreen") +
  coord_cartesian(xlim = c(0, 20), ylim = c(-100, 120), expand = FALSE) +
  theme(legend.position = "none")
p2

# PANEL A
panel_A <- p1 + p2 + plot_layout(ncol = 1)
panel_A

# PANEL B
# ATTEMPT - adding grobs to plot 1 that end at x-axis of p1
p1 <- p1 +
  annotation_custom(GROB,
                    xmin = 0,
                    xmax = POINTS$quantity[POINTS$label == "B"],
                    ymin = POINTS$value[POINTS$label == "B"],
                    ymax = POINTS$value[POINTS$label == "B"]) +
  annotation_custom(GROB,
                    xmin = POINTS$quantity[POINTS$label == "B"],
                    xmax = POINTS$quantity[POINTS$label == "B"],
                    ymin = 0,
                    ymax = POINTS$value[POINTS$label == "B"]) +
  geom_point(data = POINTS %>% filter(label == "B"), size = 1)

# ATTEMPT - adding grobs to plot 2 that extend up to meet plot 1
p2 <- p2 + annotation_custom(GROB,
                             xmin = POINTS$quantity[POINTS$label == "B"],
                             xmax = POINTS$quantity[POINTS$label == "B"],
                             ymin = POINTS$profit[POINTS$label == "B"],
                             ymax = GROB_MAX)

# Create gtable from ggplot
g2 <- ggplotGrob(p2)

# Turn clip off for panel so that line can extend above
g2$layout$clip[g2$layout$name == "panel"] <- "off"

panel_B <- p1 + g2 + plot_layout(ncol = 1)
panel_B
# Problems:
# 1. Note the shift in axes when turning the clip off so now they do not line up anymore.
# 2. Turning the clip off mean plot 2 extends below the axis. Tried experimenting with various clips.

期望 panel_B 中的图仍应像在panel_A中一样显示，但具有连接图之间点的连接线。

我正在寻求解决上述问题的帮助，或者尝试替代方法。

作为参考而不运行上面的代码 - 链接到图像，因为我无法发布它们。

面板 A

在此处输入图像描述

面板 B：它目前的样子

在此处输入图像描述

面板 B：我希望它看起来像什么！

在此处输入图像描述

标签： rggplot2plotgtable

解决方案

我的解决方案有点临时，但它似乎有效。我基于以下先前的答案Left align two graph edges (ggplot)。

我将把解决方案分成三个部分来解决您分别面临的一些问题。

与您想要的解决方案相匹配的是第三个！

一审

在这里，我使用与此答案相同的方法对齐轴Left align two graph edges (ggplot)。

# first trial 
# plots are aligned but line in bottom plot extends to the bottom
#
p1_1 <- p1 +
  annotation_custom(GROB,
                    xmin = 0,
                    xmax = POINTS$quantity[POINTS$label == "B"],
                    ymin = POINTS$value[POINTS$label == "B"],
                    ymax = POINTS$value[POINTS$label == "B"]) +
  annotation_custom(GROB,
                    xmin = POINTS$quantity[POINTS$label == "B"],
                    xmax = POINTS$quantity[POINTS$label == "B"],
                    ymin = 0,
                    ymax = POINTS$value[POINTS$label == "B"]) +
  geom_point(data = POINTS %>% filter(label == "B"), size = 1)

p2_1 <- p2 + annotation_custom(GROB,
                               xmin = POINTS$quantity[POINTS$label == "B"],
                               xmax = POINTS$quantity[POINTS$label == "B"],
                               ymin = POINTS$profit[POINTS$label == "B"],
                               ymax = GROB_MAX)

# Create gtable from ggplot
gA <- ggplotGrob(p1_1)
gB <- ggplotGrob(p2_1)

# Turn clip off for panel so that line can extend above
gB$layout$clip[gB$layout$name == "panel"] <- "off"

# get max width of left axis between both plots
maxWidth = grid::unit.pmax(gA$widths[2:5], gB$widths[2:5])

# set maxWidth to both plots (to align left axis)
gA$widths[2:5] <- as.list(maxWidth)
gB$widths[2:5] <- as.list(maxWidth)

# now apply all widths from plot A to plot B 
# (this is specific to your case because we know plot A is the one with the legend)
gB$widths <- gA$widths

grid.arrange(gA, gB, ncol=1)

在此处输入图像描述

二审

现在的问题是底部图中的线超出了绘图区域。处理此问题的一种方法是更改coord_cartesian()​​为scale_y_continuous()并且scale_x_continuous()因为这将删除掉出绘图区域的数据。

# second trial 
# using scale_y_continuous and scale_x_continuous to remove data out of plot limits
# (this could resolve the problem of the bottom plot, but creates another problem)
#
p1_2 <- p1_1 

p2_2 <- data_long %>%
  filter(variable == "profit") %>%
  ggplot(aes(x = quantity, y = value)) +
  geom_line(color = "darkgreen") +
  scale_x_continuous(limits = c(0, 20), expand = c(0, 0)) +
  scale_y_continuous(limits=c(-100, 120), expand=c(0,0)) +
  theme(legend.position = "none") + 
  annotation_custom(GROB,
                    xmin = POINTS$quantity[POINTS$label == "B"],
                    xmax = POINTS$quantity[POINTS$label == "B"],
                    ymin = POINTS$profit[POINTS$label == "B"],
                    ymax = GROB_MAX)

# Create gtable from ggplot
gA <- ggplotGrob(p1_2)
gB <- ggplotGrob(p2_2)

# Turn clip off for panel so that line can extend above
gB$layout$clip[gB$layout$name == "panel"] <- "off"


# get max width of left axis between both plots
maxWidth = grid::unit.pmax(gA$widths[2:5], gB$widths[2:5])

# set maxWidth to both plots (to align left axis)
gA$widths[2:5] <- as.list(maxWidth)
gB$widths[2:5] <- as.list(maxWidth)

# now apply all widths from plot A to plot B 
# (this is specific to your case because we know plot A is the one with the legend)
gB$widths <- gA$widths

# but now the line does not go all the way to the bottom y axis
grid.arrange(gA, gB, ncol=1)

在此处输入图像描述

第三次审判

现在的问题是这条线没有一直延伸到 y 轴的底部（因为 y=-100 下面的点被删除了）。我解决这个问题的方法（非常特别）是在 y=-100 处插入点并将其添加到数据框中。

# third trial 
# modify the data set so value data stops at bottom of plot
# 
p1_3 <- p1_1 

# use approx() function to interpolate value of x when y value == -100
xvalue <- approx(x=data_long$value, y=data_long$quantity, xout=-100)$y

p2_3 <- data_long %>%
  filter(variable == "profit") %>%
  # add row with interpolated point!
  rbind(data.frame(quantity=xvalue, variable = "profit", value=-100)) %>%
  ggplot(aes(x = quantity, y = value)) +
  geom_line(color = "darkgreen") +
  scale_x_continuous(limits = c(0, 20), expand = c(0, 0)) +
  scale_y_continuous(limits=c(-100, 120), expand=c(0,0)) +
  theme(legend.position = "none") + 
  annotation_custom(GROB,
                    xmin = POINTS$quantity[POINTS$label == "B"],
                    xmax = POINTS$quantity[POINTS$label == "B"],
                    ymin = POINTS$profit[POINTS$label == "B"],
                    ymax = GROB_MAX)

# Create gtable from ggplot
gA <- ggplotGrob(p1_3)
gB <- ggplotGrob(p2_3)

# Turn clip off for panel so that line can extend above
gB$layout$clip[gB$layout$name == "panel"] <- "off"


# get max width of left axis between both plots
maxWidth = grid::unit.pmax(gA$widths[2:5], gB$widths[2:5])

# set maxWidth to both plots (to align left axis)
gA$widths[2:5] <- as.list(maxWidth)
gB$widths[2:5] <- as.list(maxWidth)

# now apply all widths from plot A to plot B 
# (this is specific to your case because we know plot A is the one with the legend)
gB$widths <- gA$widths

# Now line goes all the way to the bottom y axis
grid.arrange(gA, gB, ncol=1)

在此处输入图像描述

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