R中有多个重复（2次，3次，......）

Question

经过一段时间的搜索，我知道这个问题还没有得到解答。 假设我有以下向量

v <- c("a", "b", "b", "c","c","c", "d", "d", "d", "d")

如何找到重复次数超过1的值

（应为"c","c","c", "d", "d", "d", "d")

超过2个重复

（应为"d", "d", "d", "d" ）

函数duplicated(v)仅返回具有重复的值。

Answer 1

您可以生成一个table() ，然后检查v哪些元素是表的相关子集的一部分，例如

R> v <- c("a", "b", "b", "c","c","c", "d", "d", "d", "d")
R> tab <- table(v)
R> tab
v
a b c d 
1 2 3 4 
R> v[v %in% names(tab[tab > 2])]
[1] "c" "c" "c" "d" "d" "d" "d"
R> v[v %in% names(tab[tab > 3])]
[1] "d" "d" "d" "d"

Answer 2

我会用ave写一个这样的简单函数：

myFun <- function(vector, thresh) {
  ind <- ave(rep(1, length(vector)), vector, FUN = length)
  vector[ind > thresh + 1] ## added "+1" to match your terminology
}

这里它适用于“v”：

myFun(v, 1)
# [1] "c" "c" "c" "d" "d" "d" "d"
myFun(v, 2)
# [1] "d" "d" "d" "d"

---

当然，总有“data.table”：

as.data.table(v)[, N := .N, by = v][N > 1 + 1]$v
# [1] "c" "c" "c" "d" "d" "d" "d"
as.data.table(v)[, N := .N, by = v][N > 2 + 1]$v
# [1] "d" "d" "d" "d"