将多个ggplot图与有或没有图例对齐 [英] Align multiple ggplot graphs with and without legends

问题描述

我试图用ggplot绘制一张图来比较两个变量的绝对值，并且还显示它们之间的比率。由于比例是无单位的，而且值不是，所以我不能在同一个y轴上显示它们，所以我想垂直堆叠成两个带有对齐x轴的单独图形。

以下是我到目前为止所得到的结果：

  library（ggplot2）
 library（dplyr）$ b $ pngalt =在这里输入图片说明> 
 b库（gridExtra）
 
＃准备一些示例数据。 
 results<  -  data.frame（index =（1:20））
 results $ control<  -  50 * results $ index 
 results $ value<  -  results $ index * 50 + 2.5 * results $ index ^ 2  -  results $ index ^ 3/8 
 results $ ratio<  -  results $ value / results $ control 
 
＃绘制绝对值
 plot_values <  -  ggplot（aes（x = index））+ 
 geom_point（aes（y = value，color =value））+ 
 geom_point（aes（y = control，color =控制））
 
＃
 plot_ratios < -  ggplot（结果，aes（x = index，y =比率））+ 
 geom_point（）
 
＃将两个图重叠在一起
 grid.arrange（plot_values，plot_ratios，ncol = 1，nrow = 2）
  

最大的问题在于第一个图的右侧的图例使其具有不同的大小。一个小问题是，我宁愿不在顶部图上显示X轴名称和刻度线，以避免混乱，并明确表示它们共享同一个轴。

我已经看过这个问题及其答案：

在ggplot中对齐绘图区域

不幸的是，这两个答案都不适合我。刻面看起来不太合适，因为我想为我的两个图形制作完全不同的y刻度。操纵ggplot_gtable返回的尺寸似乎更有希望，但我不知道如何解决这两个图具有不同数量的单元的事实。天真地复制该代码似乎没有改变我的情况下产生的图形尺寸。

这是另一个类似的问题：

在ggplot中对齐图的风险

这个问题本身似乎意味着一个很好的选择，但是rbind.gtable会抱怨如果表格有不同数量的列，这是由于图例造成的。也许有一种方法可以在第二个表中插入额外的空列？或者一种方法来抑制第一个图中的图例，然后将它重新添加到组合图中？

解决方案

这里有一个解决方案这并不需要明确使用网格图形。它使用构面，并隐藏比例的图例条目（使用 https://stackoverflow.com/a/21802022\"/a >。

  library（reshape2）
 
 results_long<  -  melt（results，id.vars （result_long $变量==ratio，ratio，values）
 results_long $ facet<  -  factor（results_long $ facet，=index）
 results_long $ facet<  -  ifelse levels = c（values，ratio））
 
 ggplot（results_long，aes（x = index，y = value，color = variable））+ 
 geom_point（）+ 
 facet_grid（facet〜。，scales =free_y）+ 
 scale_colour_manual（breaks = c（control，value），
 values = c（＃1B9E77， （color = guide_legend（title）），其中包含一个主题元素（例如D95F02，＃7570B3））+ 
主题（legend.justification = c（0,1），legend.position = c（0,1））+ 
 guides = 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 $ b $  
 
I'm trying to use ggplot to draw a graph comparing the absolute values of two variables, and also show the ratio between them. Since the ratio is unitless and the values are not, I can't show them on the same y-axis, so I'd like to stack vertically as two separate graphs with aligned x-axes.

Here's what I've got so far:

library(ggplot2)
library(dplyr)
library(gridExtra)

# Prepare some sample data.
results <- data.frame(index=(1:20))
results$control <- 50 * results$index
results$value <- results$index * 50 + 2.5*results$index^2 - results$index^3 / 8
results$ratio <- results$value / results$control

# Plot absolute values
plot_values <- ggplot(results, aes(x=index)) +
  geom_point(aes(y=value, color="value")) +
  geom_point(aes(y=control, color="control"))

# Plot ratios between values
plot_ratios <- ggplot(results, aes(x=index, y=ratio)) +
  geom_point()

# Arrange the two plots above each other
grid.arrange(plot_values, plot_ratios, ncol=1, nrow=2)
The big problem is that the legend on the right of the first plot makes it a different size. A minor problem is that I'd rather not show the x-axis name and tick marks on the top plot, to avoid clutter and make it clear that they share the same axis.

I've looked at this question and its answers:

Align plot areas in ggplot

Unfortunately, neither answer there works well for me. Faceting doesn't seem a good fit, since I want to have completely different y scales for my two graphs. Manipulating the dimensions returned by ggplot_gtable seems more promising, but I don't know how to get around the fact that the two graphs have a different number of cells. Naively copying that code doesn't seem to change the resulting graph dimensions for my case.

Here's another similar question:

The perils of aligning plots in ggplot

The question itself seems to suggest a good option, but rbind.gtable complains if the tables have different numbers of columns, which is the case here due to the legend. Perhaps there's a way to slot in an extra empty column in the second table? Or a way to suppress the legend in the first graph and then re-add it to the combined graph?
解决方案
Here's a solution that doesn't require explicit use of grid graphics. It uses facets, and hides the legend entry for "ratio" (using a technique from https://stackoverflow.com/a/21802022).
library(reshape2)

results_long <- melt(results, id.vars="index")
results_long$facet <- ifelse(results_long$variable=="ratio", "ratio", "values")
results_long$facet <- factor(results_long$facet, levels=c("values", "ratio"))

ggplot(results_long, aes(x=index, y=value, colour=variable)) +
  geom_point() +
  facet_grid(facet ~ ., scales="free_y") +
  scale_colour_manual(breaks=c("control","value"),
                      values=c("#1B9E77", "#D95F02", "#7570B3")) +
  theme(legend.justification=c(0,1), legend.position=c(0,1)) +
  guides(colour=guide_legend(title=NULL)) +
  theme(axis.title.y = element_blank())


                        
这篇关于将多个ggplot图与有或没有图例对齐的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！