将字符向量中元素的唯一组合连接到 R 中的新字符串向量中

Question

我正在尝试找到一种简单的方法（最好是单行方法）将字符向量中元素的唯一组合合并并连接到新的字符串向量中。

我还希望能够在插入的矢量组合之前、之间或之后在新矢量中包含任何文本行。组合不应以相反的顺序重复（例如 'x1_x2' 而不是 'x2_x1'），元素也不应与自身组合（不是 'x1_x1'）。

是否存在对此的快速解决方案？

所需结果的等效代码示例：

vec <- paste0("X", 1:5)
# The underscore signifies any arbitrary line of text
c(
    paste0("_", vec[1], "_", vec[2:5], "_"),
    paste0("_", vec[2], "_", vec[3:5], "_"),
    paste0("_", vec[3], "_", vec[4:5], "_"),
    paste0("_", vec[4], "_", vec[5], "_")
)

'_X1_X2_''_X1_X3_''_X1_X4_''_X1_X5_''_X2_X3_''_X2_X4_''_X2_X5_'
'_X3_X4_''_X3_X5_''_X4_X5_'

Answer 1

你可以使用

apply(combn(vec, 2), 2, \(x) paste(x, collapse = "_"))
#>  [1] "X1_X2" "X1_X3" "X1_X4" "X1_X5" "X2_X3" "X2_X4" "X2_X5" "X3_X4" "X3_X5" "X4_X5"

Answer 2

尝试combn

> sprintf("_%s_", combn(vec, 2, paste0, collapse = "_"))
 [1] "_X1_X2_" "_X1_X3_" "_X1_X4_" "_X1_X5_" "_X2_X3_" "_X2_X4_" "_X2_X5_"
 [8] "_X3_X4_" "_X3_X5_" "_X4_X5_"

> paste0("_", combn(vec, 2, paste0, collapse = "_"), "_")
 [1] "_X1_X2_" "_X1_X3_" "_X1_X4_" "_X1_X5_" "_X2_X3_" "_X2_X4_" "_X2_X5_"
 [8] "_X3_X4_" "_X3_X5_" "_X4_X5_"

Answer 3

这是另一个使用 arrangements::combinations 的选项：

paste0("_",
       apply(arrangements::combinations(x = vec, k = 2), 1, paste, collapse = "_"),
       "_")

#[1] "_X1_X2_" "_X1_X3_" "_X1_X4_" "_X1_X5_" "_X2_X3_" "_X2_X4_" "_X2_X5_" "_X3_X4_" "_X3_X5_" "_X4_X5_"

Answer 4

这是使用 crossing 的 tidyverse 版本：

library(tidyverse)

crossing(x=vec, y=vec) %>% 
  mutate(new = paste0("_",x,"_",y,"_")) %>% 
  group_by(x) %>% 
  filter(row_number()!= 1:unique(parse_number(x))) %>% 
  pull(new)

 [1] "_X1_X2_" "_X1_X3_" "_X1_X4_" "_X1_X5_" "_X2_X3_"
 [6] "_X2_X4_" "_X2_X5_" "_X3_X4_" "_X3_X5_" "_X4_X5_"

将字符向量中元素的唯一组合连接到 R 中的新字符串向量中

Concatenate unique combinations of elements in a character vector into new vector of strings in R

r

string

combinations