在 mutate 中减少分组列上的函数

Question

我有一个函数可以找到两个散文串的交集:

# Function to get intersection of words
str_intersect_by_word_list <- function(string1, string2){
  map2_chr(str_split(string1, '\\s'), str_split(string2, '\\s'), 
           ~str_c(intersect(.x, .y), collapse = " "))
} 

和一个包含要匹配的字符串的表格:

# Sample data
my_df <- tibble(
  grp = rep(LETTERS[1:3], each = 3),
  strng = c(
    "Hi I'm Abe",
    "Hi I'm Beau",
    "Hi I'm Cat",
    "Hi there I'm Doug",
    "Hi there I'm Emily",
    "Hi there I'm Finn",
    "Hi it's nice to be here",
    "Hi it's nice to meet you",
    "Hi it's nice outside"
  )
)

如果我想用公共(public)字符串创建一个列，我可以这样做:

# This works as expected
my_df %>% 
  mutate(
    common_string = my_df %>% 
      pull(strng) %>% 
      reduce(str_intersect_by_word_list)
  )

给出

# A tibble: 9 x 3
  grp   strng                    common_string
  <chr> <chr>                    <chr>        
1 A     Hi I'm Abe               Hi           
2 A     Hi I'm Beau              Hi           
3 A     Hi I'm Cat               Hi           
4 B     Hi there I'm Doug        Hi           
5 B     Hi there I'm Emily       Hi           
6 B     Hi there I'm Finn        Hi           
7 C     Hi it's nice to be here  Hi           
8 C     Hi it's nice to meet you Hi           
9 C     Hi it's nice outside     Hi           

我想用每个组共有的字符串创建一个列。但是，在分组内部，我只能访问 strng 的整个列，它提供与上面相同的输出，或者访问 strng 的当前值，这会导致错误，因为我的函数 str_intersect_by_word_list 需要两个输入。

我尝试引用 cur_data_all，但我认为这不是该函数的预期用途，而且它给我的结果与上述相同。

# This fails.
my_df %>% 
  group_by(grp) %>% 
  mutate(
    grp_string = cur_data_all() %>% 
      pull(strng) %>% 
      reduce(str_intersect_by_word_list)
  )

预期的输出是

# A tibble: 9 x 3
  grp   strng                    grp_string
  <chr> <chr>                    <chr>        
1 A     Hi I'm Abe               Hi I'm           
2 A     Hi I'm Beau              Hi I'm          
3 A     Hi I'm Cat               Hi I'm          
4 B     Hi there I'm Doug        Hi there I'm         
5 B     Hi there I'm Emily       Hi there I'm         
6 B     Hi there I'm Finn        Hi there I'm         
7 C     Hi it's nice to be here  Hi it's nice          
8 C     Hi it's nice to meet you Hi it's nice          
9 C     Hi it's nice outside     Hi it's nice          

如何获取每个组的常用词？

Answer 1

请考虑做:

my_df %>%
   group_by(grp) %>%
   mutate(common_string = str_c(reduce(str_split(strng, "\\s+"), intersect),collapse = ' '))

# A tibble: 9 x 3
# Groups:   grp [3]
  grp   strng                    common_string
  <chr> <chr>                    <chr>        
1 A     Hi I'm Abe               Hi I'm       
2 A     Hi I'm Beau              Hi I'm       
3 A     Hi I'm Cat               Hi I'm       
4 B     Hi there I'm Doug        Hi there I'm 
5 B     Hi there I'm Emily       Hi there I'm 
6 B     Hi there I'm Finn        Hi there I'm 
7 C     Hi it's nice to be here  Hi it's nice 
8 C     Hi it's nice to meet you Hi it's nice 
9 C     Hi it's nice outside     Hi it's nice