R中的多次重复（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 次的值

（应该是"c","c","c", "d", "d", "d", "d")

且重复次数超过 2 次

（应该是"d", "d", "d", "d"）

函数 duplicated(v) 只有 returns 个值有重复。

Answer 1

您可以生成一个 table()，然后检查 v 的哪些元素是 table 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

我会使用 ave 编写一个简单的函数，如下所示：

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

此处应用于"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"

R中的多次重复（2次，3次，...）

Multiple duplicates (2 times, 3 times,...) in R

duplicate-data

r

duplicates