通过使用is_empty（），用na替换字符（0）的列表元素

Question

我有一个dataframe（my_df），其中一行中，带有cartare（0）的列表。

我想通过使用rlang的is_empty（）替换na_character。我知道通过使用例如长度（x）== 0有解决方法，但是我试图理解为什么我使用iS_empty（）的方法不起作用。感谢任何提示。

library(tidyverse)

my_df <- data.frame(
  stringsAsFactors = FALSE,
              type = c("house", "tent", "treehouse, mainhouse")
) %>% 
  mutate(house=str_extract_all(type, regex("house")))
  
my_df
#>                   type        house
#> 1                house        house
#> 2                 tent             
#> 3 treehouse, mainhouse house, house
class(my_df$house)
#> [1] "list"

my_df %>% 
  mutate(house_mod=modify_if(house,
                             .p = is_empty(house),
                             .f = NA_character_))
#> Error in `mutate()`:
#> ! Problem while computing `house_mod = modify_if(house, .p =
#>   is_empty(house), .f = NA_character_)`.
#> Caused by error in `probe()`:
#> ! length(.p) == length(.x) is not TRUE

my_df <- my_df %>% 
  mutate(house_empty=map(house, ~is_empty(.))) 
my_df
#>                   type        house house_empty
#> 1                house        house       FALSE
#> 2                 tent                     TRUE
#> 3 treehouse, mainhouse house, house       FALSE

my_df %>% 
  mutate(house_mod=modify_if(house,
                             .p = house_empty==T,
                             .f = NA_character_))
#> Error in `mutate()`:
#> ! Problem while computing `house_mod = modify_if(house, .p = house_empty
#>   == T, .f = NA_character_)`.
#> ✖ `house_mod` must be size 3 or 1, not 2.

^由

Answer 1

.f参数应采用一个函数，但是您刚刚通过na_character _。尝试〜na_character _：

my_df %>% 
     mutate(house_mod=modify_if(house,
                                .p = is_empty,
                                .f = ~NA_character_))
#>                   type        house    house_mod
#> 1                house        house        house
#> 2                 tent                        NA
#> 3 treehouse, mainhouse house, house house, house