如何从数据框中获取所有可能的列组合？

Question

R> set.seed(123)
R> data <- matrix(rnorm(6),3,10)
R> colnames(data) <- c("s1","s2","s3","s4","s5","s6","s7","s8","s9","s10")
R> print(data)

sorry, I don't know how to show the print

我想通过 R 包从数据框中获取所有可能的列组合？时间越短越好

结果是这样的，

All possible two pair combination
column S1 and S2
column S2 and S3
column S3 and S4
...

all possible three pair combination
column S1, S2 and S3
column S2, S3 and S4
column S3, S4 and S5
...

Answer 1

我已经做了一个函数来做这个，只要我需要它就派上用场：

make_combinations <- function(x) {

  l <- length(x)
  mylist <- lapply(2:l, function(y) {
    combn(x, y, simplify = FALSE)
  })
  mylist

}


results <- make_combinations(colnames(data))
results[[1]]
# [[1]]
# [1] "s1" "s2"
# 
# [[2]]
# [1] "s1" "s3"
# 
# [[3]]
# [1] "s1" "s4"
# 
# [[4]]
# [1] "s1" "s5"
# 
# [[5]]
# [1] "s1" "s6"
# 
# [[6]]
# [1] "s1" "s7"
#and so on...

函数输出一个列表，其中每个元素都是另一个列表，包含所有 2-way、3-way、4-way... 组合。在您的情况下，它有 9 个元素，从 2 路组合一直到 10 路组合。