R語言 case when 函式

要點有兩個

不匹配的時候會返回 na，而不是保持不變

根據順序進行條件判斷，順序很重要

下面這段**，

x <- 1:50

case_when(
x %% 35 == 0 ~ "fizz buzz",
x %% 5 == 0 ~ "fizz",
x %% 7 == 0 ~ "buzz",
true ~ as.character(x)
)

[1] na          na          na          na          "fizz"      na         

[7] "buzz" na na "fizz" na na 
[13] na "buzz" "fizz" na na na 
[19] na "fizz" "buzz" na na na 
[25] "fizz" na na "buzz" na "fizz" 
[31] na na na na "fizz buzz" na 
[37] na na na "fizz" na "buzz" 
[43] na na "fizz" na na na 
[49] "buzz" "fizz"

x <- 1:50

case_when(
x %% 35 == 0 ~ "fizz buzz",
x %% 5 == 0 ~ "fizz",
x %% 7 == 0 ~ "buzz",
true ~ as.character(x)
)#> [1] "1" "2" "3" "4" "fizz" "6" 
#> [7] "buzz" "8" "9" "fizz" "11" "12" 
#> [13] "13" "buzz" "fizz" "16" "17" "18" 
#> [19] "19" "fizz" "buzz" "22" "23" "24" 
#> [25] "fizz" "26" "27" "buzz" "29" "fizz" 
#> [31] "31" "32" "33" "34" "fizz buzz" "36" 
#> [37] "37" "38" "39" "fizz" "41" "buzz" 
#> [43] "43" "44" "fizz" "46" "47" "48" 
#> [49] "buzz" "fizz" 
# like an if statement, the arguments are evaluated in order, so you must
# proceed from the most specific to the most general. this won't work:
case_when(
true ~ as.character(x),
x %% 5 == 0 ~ "fizz",
x %% 7 == 0 ~ "buzz",
x %% 35 == 0 ~ "fizz buzz"
)#> [1] "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" "11" "12" "13" "14" "15"
#> [16] "16" "17" "18" "19" "20" "21" "22" "23" "24" "25" "26" "27" "28" "29" "30"
#> [31] "31" "32" "33" "34" "35" "36" "37" "38" "39" "40" "41" "42" "43" "44" "45"
#> [46] "46" "47" "48" "49" "50"

starwars %>%

select(name:mass, gender, species) %>%
mutate(
type = case_when(
height > 200 | mass > 200 ~ "large",
species == "droid" ~ "robot",
true ~ "other"
))

case_character_type <- function(height, mass, species) 

case_character_type(150, 250, "droid")
#> [1] "large"
case_character_type(150, 150, "droid")
#> [1] "robot"

R語言 case when 函式

要點有兩個 不匹配的時候會返回 na，而不是保持不變 根據順序進行條件判斷，順序很重要 下面這段 x 1 50 case when x 35 0 fizz buzz x 5 0 fizz x 7 0 buzz true as.character x 如果不包含true as.character x ...

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