当添加具有不同数据的图层时，ggplot对象未找到错误 [英] ggplot object not found error when adding layer with different data

问题描述

我有一些积分，我想用segment来连接它们。

  dummy = data.frame （GROUP = c（A，B，C，D），
 X = c（80,75,68,78），
 Y = c（30,32 （80），x2 = c（78），y1 = c（30），y2 = c（33），b3 b）b 
 
 df = data.frame ））
 df 
 library（ggplot2）
 ggplot（dummy，aes（x = X，y = Y，color = GROUP））+ 
 geom_point（）+ 
 geom_segment（aes（x = x1，y = y1，xend = x2，yend = y2），data = df）
  

但我得到这个错误$ / $>

$ pre $ eval（expr，envir，enclos）中的错误：object'GROUP'not发现


我在这里做错了什么？

ggplot 调用中定义的美学映射将被所有图层继承。由于您使用 color = GROUP 初始化了您的绘图，因此 ggplot 会查找 GROUP code>>列，如果它不存在则抛出一个错误。有三个很好的选择可以解决这个问题：

选项1：设置 inherit.aes = F 在你不想继承美学的层中。大多数时候这是最好的选择。

  ggplot（dummy，aes（x = X，y = Y，color = GROUP））+ 
 geom_point（）+ 
 geom_segment（aes（x = x1，y = y1，xend = x2，yend = y2），
 data = df，
 inherit .aes = FALSE）
  

选项2：只指定您想要的美学在顶层调用中被继承（或者你将覆盖） - 在层级设置其他美学：

  ggplot（dummy ，aes（x = x，y = y））+ 
 geom_point（aes（color = GROUP））+ 
 geom_segment（aes（x = x1，y = y1，xend = x2，yend = y2 ），
 data = df）
  

选项3： NULL 图层上的美学效果不适用。

  ggplot（ dummy，aes（x = X，y = Y，color = GROUP））+ 
 geom_point（）+ 
 geom_segment（aes（x = x1，y = y1，xend = x2，yend = y2，颜色= NULL），
 data = df）
  

---

使用哪一个？

大部分时间选项1都很好。然而，如果你想让一层美学继承一层，而你只想修改一个或两个，可能会很烦人。也许你在图中添加了一些错误条，并在主数据中使用了相同的 x 和 color 列名，错误栏数据，但是您的错误栏数据没有 y 列。这是使用选项2或选项3以避免重复 x 和颜色映射的好时机。 p>

I have a plot with some points and I'd like to use segment to connect them

dummy = data.frame(GROUP=c("A","B","C","D"),
                   X = c(80,75,68,78),
                   Y=c(30, 32,36,33)

)
df= data.frame(x1 = c(80), x2 =c(78) , y1=c(30), y2 =c(33))
df
library(ggplot2)
ggplot(dummy,aes(x=X,y=Y,color=GROUP)) + 
  geom_point() +
  geom_segment(aes(x=x1,y=y1,xend= x2, yend =y2), data = df) 

but I get this error

Error in eval(expr, envir, enclos) : object 'GROUP' not found

What am I doing wrong here?

解决方案

Aesthetic mapping defined in the initial ggplot call will be inherited by all layers. Since you initialized your plot with color = GROUP, ggplot will look for a GROUP column in subsequent layers and throw an error if it's not present. There are 3 good options to straighten this out:

Option 1: Set inherit.aes = F in the layer the you do not want to inherit aesthetics. Most of the time this is the best choice.

ggplot(dummy,aes(x = X, y = Y, color = GROUP)) + 
  geom_point() +
  geom_segment(aes(x = x1, y = y1, xend = x2, yend = y2),
               data = df,
               inherit.aes = FALSE) 

Option 2: Only specify aesthetics that you want to be inherited (or that you will overwrite) in the top call - set other aesthetics at the layer level:

ggplot(dummy,aes(x = X, y = Y)) + 
  geom_point(aes(color = GROUP)) +
  geom_segment(aes(x = x1, y = y1, xend = x2, yend = y2),
               data = df) 

Option 3: Specifically NULL aesthetics on layers when they don't apply.

ggplot(dummy,aes(x = X, y = Y, color = GROUP)) + 
  geom_point() +
  geom_segment(aes(x = x1, y = y1, xend = x2, yend = y2, color = NULL),
               data = df) 

---

Which to use?

Most of the time option 1 is just fine. It can be annoying, however, if you want some aesthetics to be inherited by a layer and you only want to modify one or two. Maybe you are adding some errorbars to a plot and using the same x and color column names in your main data and your errorbar data, but your errorbar data doesn't have a y column. This is a good time to use Option 2 or Option 3 to avoid repeating the x and color mappings.)

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