r - 从多个向量中找出至少按百分比出现的公共(public)元素

Question

假设我有 4 个向量:

a <- c("Mark","Kate","Greg", "Mathew")
b <- c("Mark","Tobias","Mary", "Mathew", "Greg")
c <- c("Mary","Chuck","Igor", "Mathew", "Robin", "Tobias")
d <- c("Kate","Mark","Igor", "Greg", "Robin", "Mathew")

我想从这些向量中选择重叠的名称，并假设该名称必须出现在这 4 个向量中的至少 3 个中。当然，我想让使用名称必须存在的矢量百分比变得容易。

我可以修改 intersect 吗？

Answer 1

我认为这会奏效。我们使用 table 函数来完成大部分繁重的工作。

find_perc <- function(..., perc = .75){
    list_len <- length(list(...)) # how many vectors
    tab_it <- table(c(...)) # tabulate all the names
    tab_it_perc <- tab_it / list_len # calculate the frequencies
    names(tab_it_perc[tab_it_perc >= perc]) # return those with freq >= perc
}


> find_perc(a, b, c, d)
[1] "Greg"   "Mark"   "Mathew"
> find_perc(a, b, c, d, perc = .5)
[1] "Greg"   "Igor"   "Kate"   "Mark"   "Mary"   "Mathew" "Robin"  "Tobias"