R: "stack"列在彼此之上

Question

假设我有一些这样的数据:

library(dplyr)

a = data.frame( "col" = c("red", "red", "green"), "coll" = c("blue", "blue", "yellow"))

我试图从“a”中获取所有唯一值并将它们放入一个新框架中:

final = data.frame("col" = c("red", "green", "blue", "yellow")

我尝试了以下方法:

first_col = a %>% distinct(col)
second_col = a %>% distinct(coll)

final = cbind(first_col, second_col)

但这似乎并不正确。
有人可以告诉我我做错了什么吗？
谢谢

Answer 1

您可以使用 union与 Reduce使它

> data.frame(a = Reduce(union, a))
       a
1    red
2  green
3   blue
4 yellow