r - 仅针对 1 个变量组合数据帧 R

Question

我有一个具有以下结构的data.frame：

x1 x2 x3 x4 x5 x6
 y  n  y  n  n  y
 n  n  y  n  n  y
 y  y  y  y  y  n

我想组合combn()但仅使用 1 个变量，我的意思是，得到这个结果：

x1 x2
x1 x3
x1 x4
x1 x5
x1 x6

而不是：（有太多我不需要的变量，我想选择 x[i]）

x1 x2
...
x2 x1
x2 x2
...
x6 x5

谢谢

Answer 1

使用这些数据

your_data = structure(list(x1 = structure(c(2L, 1L, 2L), .Label = c("n", 
"y"), class = "factor"), x2 = structure(c(1L, 1L, 2L), .Label = c("n", 
"y"), class = "factor"), x3 = structure(c(1L, 1L, 1L), .Label = "y", class = "factor"), 
    x4 = structure(c(1L, 1L, 2L), .Label = c("n", "y"), class = "factor"), 
    x5 = structure(c(1L, 1L, 2L), .Label = c("n", "y"), class = "factor"), 
    x6 = structure(c(2L, 2L, 1L), .Label = c("n", "y"), class = "factor")), .Names = c("x1", 
"x2", "x3", "x4", "x5", "x6"), class = "data.frame", row.names = c(NA, 
-3L))

这与您要求的输出相匹配：

cbind(names(your_data)[1], names(your_data)[-1])
#      [,1] [,2]
# [1,] "x1" "x2"
# [2,] "x1" "x3"
# [3,] "x1" "x4"
# [4,] "x1" "x5"
# [5,] "x1" "x6"

这是一个矩阵，但您可以使用as.data.frame. 您还可以根据您想要在第一个位置的列号对其进行功能化。

single_combn = function(vec, pos) {
    cbind(vec[pos], vec[-pos])
}

使用示例：

single_combn(names(your_data), 1)
#      [,1] [,2]
# [1,] "x1" "x2"
# [2,] "x1" "x3"
# [3,] "x1" "x4"
# [4,] "x1" "x5"
# [5,] "x1" "x6"

single_combn(names(your_data), 3)
#      [,1] [,2]
# [1,] "x3" "x1"
# [2,] "x3" "x2"
# [3,] "x3" "x4"
# [4,] "x3" "x5"
# [5,] "x3" "x6"