如何计算R中不同点之间的过渡次数

Question

我是R的初学者

我有一个点向量，例如：

point <- c("A","B","B","C","C","A","A","C","B","A","B","A","A","C")

我想统计不同点之间的转换次数。这意味着我希望输出为：

Transit_A_B: 2;
Transit_A_C: 2;
Transit_B_C: 1;
Transit_B_A: 2;
Transit_C_B: 1;
Transit_C_A: 1.

非常感谢任何能帮助我的人。

Answer 1

这可能会：

p1 <- head(point, -1)
p2 <- point[-1]
keep <- p1 != p2
table(paste0("Transit_", p1[keep], "_", p2[keep]))
#R> 
#R> Transit_A_B Transit_A_C Transit_B_A Transit_B_C Transit_C_A Transit_C_B 
#R>           2           2           2           1           1           1

如果你想要像你这样的打印输出：

p1 <- head(point, -1)
p2 <- point[-1]
keep <- p1 != p2
out <- table(paste0("Transit_", p1[keep], "_", p2[keep]))

cat(paste0(names(out), ": ", out, 
           ifelse(seq_along(out) == length(out), ".", ";")),
    sep = "\n")
#R> Transit_A_B: 2;
#R> Transit_A_C: 2;
#R> Transit_B_A: 2;
#R> Transit_B_C: 1;
#R> Transit_C_A: 1;
#R> Transit_C_B: 1.

Answer 2

也许你可以像下面那样尝试embed

df <- rev(data.frame(embed(point, 2)))
res <- table(
  paste0(
    "Transit_",
    do.call(paste, c(subset(df, do.call("!=", df)), sep = "_"))
  )
)

这给出了

> res

Transit_A_B Transit_A_C Transit_B_A Transit_B_C Transit_C_A Transit_C_B
          2           2           2           1           1           1

如果您更喜欢数据框格式的结果，您可以应用 stack 而不是 res，例如，

> stack(res)
  values         ind
1      2 Transit_A_B
2      2 Transit_A_C
3      2 Transit_B_A
4      1 Transit_B_C
5      1 Transit_C_A
6      1 Transit_C_B

如何计算R中不同点之间的过渡次数

How to count the number of transition between different points in R

r

transition

point