如何围绕 data.table::tstrsplit() 编写一个函数来将字符串分成不同的列？

Question

这个问题可能是重复的，但我没有找到解决方案，所以提前道歉。 我想构建一个更快的替代tidyr::separate()，它将一列中的字符串分成新列。我决定使用data.table 来完成这项任务。

我创建了以下函数：

library(data.table)
library(tibble)

fast_separate <- function(.data, origin_col, into) {
  
  my_origin_col <- deparse(substitute(origin_col))
  
  my_dt <- as.data.table(.data)
  my_dt <- my_dt[, into := tstrsplit(my_origin_col, "_", fixed = TRUE)][] # https://rdatatable.gitlab.io/data.table/reference/tstrsplit.html
  as_tibble(my_dt)
}

---

我的功能失败
假设我有以下玩具数据：

df_toms <- tribble(~toms, 
              "tom_hanks",
              "tom_bradey",
              "tom_cruise",
              "thomas_edison",
              "thomas_fefferson"
              )

df_toms
## # A tibble: 5 x 1
##   toms            
##   <chr>           
## 1 tom_hanks       
## 2 tom_bradey      
## 3 tom_cruise      
## 4 thomas_edison   
## 5 thomas_fefferson

当我打电话给fast_separate() 我得到：

fast_separate(df_toms, origin_col = toms, into = c("first_name", "surname"))

## # A tibble: 5 x 2
##   toms             into 
##   <chr>            <chr>
## 1 tom_hanks        toms 
## 2 tom_bradey       toms 
## 3 tom_cruise       toms 
## 4 thomas_edison    toms 
## 5 thomas_fefferson toms 

这不是所需的输出。
这很奇怪，因为我们会定期运行相同的代码（即不在函数内部）：

my_dt <- as.data.table(df_toms)
my_dt <- my_dt[, c("first_name", "surname") := tstrsplit(toms, "_", fixed = TRUE)][]
desired_output <- as_tibble(my_dt)

desired_output 
## # A tibble: 5 x 3
##   toms             first_name surname  
##   <chr>            <chr>      <chr>    
## 1 tom_hanks        tom        hanks    
## 2 tom_bradey       tom        bradey   
## 3 tom_cruise       tom        cruise   
## 4 thomas_edison    thomas     edison   
## 5 thomas_fefferson thomas     fefferson

---

我写fast_separate()的方式有什么问题？

Answer 1

这提供了所需的输出

library(data.table)
library(tibble)
fast_separate <- function(.data, origin_col, into) {
  as.tibble(setDT(.data)[, (into) := tstrsplit(.data[[origin_col]], "_", fixed = TRUE)])
}

df_toms <- tribble(~toms, 
                   "tom_hanks",
                   "tom_bradey",
                   "tom_cruise",
                   "thomas_edison",
                   "thomas_fefferson"
)


fast_separate(df_toms, origin_col = "toms", into = c("first_name", "surname"))
# # A tibble: 5 x 3
#   toms             first_name surname  
#   <chr>            <chr>      <chr>    
# 1 tom_hanks        tom        hanks    
# 2 tom_bradey       tom        bradey   
# 3 tom_cruise       tom        cruise   
# 4 thomas_edison    thomas     edison   
# 5 thomas_fefferson thomas     fefferson

Thomas Fefferson 是谁？ ;-)