如何在R中从vector创建edgelist

Question

我有一个像这样的矢量：

c("A", "B", "C", "D", "E", "F")

我想创建一个类似的数据帧

"from" "to"
A B
B C
C D
D E
E F

我怎么能做到这一点？

Answer 1

其他方式：

data.frame(from = vec[-length(vec)], to = vec[-1])

Answer 2

以下是使用embed和重新排列列的一种方法：

# data
temp <- c("A", "B", "C", "D", "E", "F")

embed(temp, 2)[, c(2,1)]

     [,1] [,2]
[1,] "A"  "B" 
[2,] "B"  "C" 
[3,] "C"  "D" 
[4,] "D"  "E" 
[5,] "E"  "F"

将它放入data.frame，将其包装在data.frame:

setNames(data.frame(embed(temp, 2)[, c(2,1)]), c("from", "to"))
  from to
1    A  B
2    B  C
3    C  D
4    D  E
5    E  F

Answer 3

na.omit(data.frame(from = vec, to = dplyr::lead(vec)))
  from to
1    A  B
2    B  C
3    C  D
4    D  E
5    E  F

Answer 4

另一种方法是使用zoo包，

library(zoo)
rollapply(vec, 2, by = 1, paste)

Answer 5

我们也可以这样做：

vec <- c("A", "B", "C", "D", "E", "F")
x <- rep(seq(length(vec)), each=2)[-length(vec)*2][-1]
# [1] 1 2 2 3 3 4 4 5 5 6
data.frame(matrix(vec[x], ncol = 2, byrow = T))

或者：

data.frame(t(sapply(seq(length(vec)-1), function(i) c(vec[i], vec[i+1]))))

  # X1 X2
# 1  A  B
# 2  B  C
# 3  C  D
# 4  D  E
# 5  E  F