仅保留条件重复的条目

Question

我正在清理数据集，我只需要保留重复4次的数据集（例如“ a”和“ b”），但是，我无法做到这一点。谁能帮忙吗？

谢谢！

let <- c("a","a","a","a","b","b","b","b","c","c","c","d","d","e")
avg <- c(1,1,1,2,3,4,5,6,1,2,3,4,3,5)

sample <- data.frame(let,avg)

Answer 1

我们可以使用data.table

library(data.table)
setDT(sample)[, .SD[.N >=4], let]
#   let avg
#1:   a   1
#2:   a   1
#3:   a   1
#4:   a   2
#5:   b   3
#6:   b   4
#7:   b   5
#8:   b   6

---

或者使用base R的{​​{1}}

ave

或与sample[with(sample, ave(avg, let, FUN = length)>=4),]

table