dplyr和ggplot管道没有按预期工作 [英] dplyr and ggplot piping is not working as expected

问题描述

我找不到以下两个问题的解决方案：

首先我试试这个：

  library（tidyverse）
 gg<  -  mtcars％>％
 mutate（group = ifelse（gear == 3,1,2））％>％
 ggplot（aes（x = carb，y = drat））+ geom_point（shape = group）
 
图层中的错误（data = data，mapping = mapping，stat = stat，geom = 
 GeomPoint，：object'group'not found 
  

这显然不起作用。 。$ group 也不是成功的。 / p>

第二个问题是，我无法在管道中调用保存的ggplot（ gg ）。

  gg < -  mtcars％>>％
 mutate（group = ifelse（gear == 3,1， 2））％>％
 ggplot（aes（x = carb，y = drat））+ geom_point（）
 
 
 mtcars％>％
 filter （vs == 0）％>％
 gg + geom _point（aes（x = carb，y = drat），size = 4）
 
 gg（。）中的错误：找不到函数gg
  
  
 $ b  
 $ b 
感谢您的帮助！
 $ b $ h1>编辑 
 
 
经过很长时间，我发现了一个解决方案此处。必须在 {} 中设置完整的ggplot项。
  mtcars ％>％
 mutate（group = ifelse（gear == 3,1,2））％>％{
 ggplot（。，aes（carb，drat））+ 
 geom_point （shape =。$ group）} 
  
 
 
解决方案
你的 shape 定义在 aes（）中，你可以得到想要的行为。要在 aes（）之外使用 shape ，您可以将它传递给一个值（即 shape = 1 ）。另请注意，当您将连续变量传递给<$时， group 会转换为离散变量， geom_point 会引发错误c $ c> shape 。
  library（tidyverse）
 
 gg <  -  mtcars％>％
 mutate（group = ifelse（gear == 3,1,2））％>％
 ggplot（aes（x = carb，y = drat））+ 
 geom_point（aes（shape = as.factor（group）））
 
 gg 
  
其次，当 lhs％>％rhs 被调用时，％>％ ，假定 rhs 是一个函数。因此，如错误所示，您正在调用 gg 作为函数。在数据框上调用一个函数作为一个函数（即 gg（mtcars））不是一个有效的操作。 
 
 
请参阅@docendo对如何使用 {} 来完成将图层添加到现有的 ggplot 对象的问题进行了评论一个magrittr管道。 
I find no solution for these two following issues:

First I try this:
library(tidyverse)
gg <- mtcars %>% 
      mutate(group=ifelse(gear==3,1,2)) %>%      
      ggplot(aes(x=carb, y=drat)) + geom_point(shape=group)

Error in layer(data = data, mapping = mapping, stat = stat, geom = 
GeomPoint,:object 'group' not found
which is obviously not working. But using something like this .$group is also not successfull. Of note, I have to specifiy the shape outside from aes() 

The second problem is this. I'm not able to call a saved ggplot (gg) within a pipe.
gg <- mtcars %>% 
      mutate(group=ifelse(gear==3,1,2)) %>%      
      ggplot(aes(x=carb, y=drat)) + geom_point()


    mtcars %>% 
        filter(vs == 0) %>% 
        gg + geom_point(aes(x=carb, y=drat), size = 4)  

Error in gg(.) : could not find function "gg"
Thanks for your help!

Edit

After a long time I found a solution here. One has to set the complete ggplot term in {}.
mtcars %>% 
   mutate(group=ifelse(gear==3,1,2)) %>% {     
   ggplot(.,aes(carb,drat)) +
       geom_point(shape=.$group)}

解决方案
If you wrap your shape definition in aes() you can get the desired behavior.  To use shape outside of aes() you can pass it a single value (ie shape=1).  Also note that group is converted to a discrete var, geom_point throws an error when you pass a continuous var to shape.
library(tidyverse)

gg <- mtcars %>% 
  mutate(group=ifelse(gear==3,1,2)) %>%      
  ggplot(aes(x=carb, y=drat)) + 
  geom_point(aes(shape=as.factor(group)))

gg
Second, the %>% operator, when called as lhs %>% rhs, assumes that the rhs is a function.  So as the error shows, you are calling gg as a function.  Calling a plot as a function on a dataframe (ie gg(mtcars)) isnt a valid operation.

See @docendo discimus comment on the question for how to use {} to accomplish adding a layer to an existing ggplot object from a magrittr pipeline.

                        
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