隔行扫描两个向量

Question

假设我有两个向量定义如下:

a <- c("a1", "a2", "a3")
b <- c("b1", "b2", "b3")

现在我想最终得到一个像这样的字符串向量:

c("a1","b1", "a2", "b2", "a3", "b3")

这可能吗？

Answer 1

你可以rbind,然后强制回到矢量.

a <- c("a1", "a2", "a3") 
b <- c("b1", "b2", "b3")
c(rbind(a,b))

# [1] "a1" "b1" "a2" "b2" "a3" "b3"

正如@Moody_Mudskipper指出的那样,as.vector(rbind(a,b)))速度更快

对于长度不同的情况,我在此链接中找到了Rolf Turner的以下解决方案:http://r.789695.n4.nabble.com/Interleaving-elements-of-two-vectors-td795123.html

riffle <- function (a,b) { 
  n  <- min(length(a),length(b)) 
  p1 <- as.vector(rbind(a[1:n],b[1:n])) 
  p2 <- c(a[-(1:n)],b[-(1:n)]) 
  c(p1,p2) 
} 

riffle(1:3, letters[1:5])

# [1] "1" "a" "2" "b" "3" "c" "d" "e"