使用具有多个真实条件的case_when

Question

这段代码

library(dplyr)

letters = c("A","B","C")
numbers = c(4, 15, 35)

df <- data.frame(letters, numbers)

df %>% 
  mutate(category = case_when(
    numbers %% 5 == 0 ~ "fizz",
    numbers %% 7 == 0 ~ "buzz",
    TRUE ~ as.character(numbers)
  )
  )

产生如下数据帧：

  letters numbers category
1       A       4        4
2       B      15     fizz
3       C      35     fizz

我想看到的结果是这个数据框：

  letters numbers category
1       A       4        4
2       B      15     fizz
3       C      35     fizz
4       C      35     buzz

因为对于行C有两个条件为真，所以我希望为它们中的每一个创建一行。我怎样才能做到这一点？

Answer 1

case_when/ifelse将仅返回条件1的输出。您可以这样做：

library(dplyr)
df %>% 
  mutate(category = case_when(
    numbers %% 5 == 0 & numbers %% 7 == 0 ~ "fizz, buzz",
    numbers %% 5 == 0 ~ "fizz",
    numbers %% 7 == 0 ~ "buzz",
    TRUE ~ as.character(numbers))) %>% 
    tidyr::separate_rows(category)

#  letters numbers category
#  <chr>     <dbl> <chr>   
#1 A             4 4       
#2 B            15 fizz    
#3 C            35 fizz    
#4 C            35 buzz