将列表转换为 R 中长度相同的嵌套命名向量

Question

Suppose for the list x

x <- list(a = c(1, 2, 3), b = c(4, 5))

I want to get back a named vector with the same length that looks like

c(a = c(1, 2, 3), b = c(4, 5))

My first thoughts use a for loop

  out <- vector(typeof(x), length(x))
  x_names <- names(x)
  for (i in seq_along(x)) {
    out[i] <- x[[i]]
  }
  
  names(out) <- c(x_names)

Is there a way to do this without a for loop?

Answer 1

How about using do.call() with c() ?

do.call(c,x)

or

unlist(x)

Output

a1 a2 a3 b1 b2 
 1  2  3  4  5 

Answer 2

• Just use

lapply(1:length(x) , \(i) unlist(x[i]))

#> [[1]]
#> a1 a2 a3 
#>  1  2  3 
#> 
#> [[2]]
#> b1 b2 
#>  4  5