r语言 - 如何根据不同列的值从一列选择值?

Question

我有一个字符列表:

list <- c("dog", "cat", "fish")

和df是这样的:

df = tibble(animal = c("dog", "fish", "frog", "cat", "shark"), plant = c("tree", "daisy", "mushroom", "grass", "dafodil"))
print(df)
# A tibble: 5 × 2
animal plant   
<chr>  <chr>   
1 dog    tree    
2 fish   daisy   
3 frog   mushroom
4 cat    grass   
5 shark  dafodil

我想生成一个与上面的动物列表相对应的植物列表，它看起来像:

plant_list 
c("tree", "grass" "daisy")

我试过了

plant_list <- c()
for (i in list){
if (df$animal == i){
plant_list <- append(plant_list, df$plant)
} else {}
}

但是这给了我一个错误。什么是好的解决方案?(最好使用dplyr，但无论如何都会很棒!)

Answer 1

您可以使用-

df$plant[df$animal %in% list]
#[1] "tree"  "daisy" "grass"

Answer 2

你可以试试

anmal <- c("dog", "cat", "fish")
df %>%
filter(animal %in% anmal) %>%
pull(plant)
[1] "tree"  "daisy" "grass"