在 dplyr 流程中引用当前 data.frame

Question

如何在 dpylr 流中引用当前的 data.frame？举个例子，在

library(dplyr)

myresults = tribble(
  ~dataset_name, ~method_group, ~method, ~value,
  'iris',        'other',       'a',     1,
  'wine',        'other',       'b',     2,
  'iris',        'mine',        'c',     3,
  'wine',        'mine',        'd',     4
)

myresults %>%
  mutate(dataset_name='datasets aggregated') %>%
  bind_rows(XXX %>% filter(method=='c') %>% mutate(method_group = 'other'))

我想将当前的 data.frame 与其自身进行行绑定。除了 XXX 我应该写什么？

在函数

do()

中，答案似乎是

.

。尽管这不是很优雅，而且我不想使用 do，但我设法获得了想要的结果

myresults %>%
  mutate(dataset_name='datasets aggregated') %>%
  do(bind_rows(data.frame(.), data.frame(.) %>% filter(method=='c') %>% mutate(method_group = 'other')))

但这不太好。

我的R版本是：

> R.version
               _                           
platform       x86_64-pc-linux-gnu         
arch           x86_64                      
os             linux-gnu                   
system         x86_64, linux-gnu           
status                                     
major          3                           
minor          4.4                         
year           2018                        
month          03                          
day            15                          
svn rev        74408                       
language       R                           
version.string R version 3.4.4 (2018-03-15)
nickname       Someone to Lean On 

Answer 1

我看到的三个选项：

1. 将

   .

   移至

   filter

   内，因为它似乎知道要做什么：

   myresults %>%
     mutate(dataset_name='datasets aggregated') %>%
     bind_rows(filter(., method=='c') %>% mutate(method_group = 'other'))
   # # A tibble: 5 x 4
   #   dataset_name        method_group method value
   #   <chr>               <chr>        <chr>  <dbl>
   # 1 datasets aggregated other        a          1
   # 2 datasets aggregated other        b          2
   # 3 datasets aggregated mine         c          3
   # 4 datasets aggregated mine         d          4
   # 5 datasets aggregated other        c          3
   

2. 使用临时变量，中间管道：

   z <- myresults %>% mutate(dataset_name='datasets aggregated')
   bind_rows(z, z %>% filter(method=='c') %>% mutate(method_group = 'other'))
   # # A tibble: 5 x 4
   #   dataset_name        method_group method value
   #   <chr>               <chr>        <chr>  <dbl>
   # 1 datasets aggregated other        a          1
   # 2 datasets aggregated other        b          2
   # 3 datasets aggregated mine         c          3
   # 4 datasets aggregated mine         d          4
   # 5 datasets aggregated other        c          3
   

3. 与您的

   do

   实现类似。 （您不需要

   data.frame(.)

   ，这有点多余，但是

   do

   显然不会替换嵌套管道中

   .

   的实例。）

   myresults %>%
     mutate(dataset_name='datasets aggregated') %>%
     do({dat <- .; bind_rows(dat, dat %>% filter(method=='c') %>% mutate(method_group = 'other'))})
   # # A tibble: 5 x 4
   #   dataset_name        method_group method value
   #   <chr>               <chr>        <chr>  <dbl>
   # 1 datasets aggregated other        a          1
   # 2 datasets aggregated other        b          2
   # 3 datasets aggregated mine         c          3
   # 4 datasets aggregated mine         d          4
   # 5 datasets aggregated other        c          3
   

Answer 2

比 @r2evans 的解决方案更通用的解决方案是使用匿名函数

myresults %>%
  mutate(dataset_name='datasets aggregated') %>%
  (\(.) bind_rows(., filter(., method=='c') %>% mutate(method_group = 'other')))() #NOTE : `()` at the end is optional for the `dplyr` pipe but compulsory with the base R pipe (|>)