R:如何将向量扩展到更大的长度，保持其唯一值

Question

假设我们有一个向量，如下所示：

countries <- c("UK", "Germany", "Italy", "Denmark")

我想从中创建另一个，但更像下面的：

countries_long <- c("UK", "UK", "UK", "UK", "Germany", "Germany", "Italy", "Italy", "Denmark", "Denmark", "Denmark")

我怎样才能取得这样的结果？

Answer 1

> rep(countries, c(4,2,2,3))
[1] "UK"      "UK"      "UK"      "UK"      "Germany" "Germany" "Italy"   "Italy"   "Denmark" "Denmark" "Denmark"
>