List into tibble using list names as values in one column

Question

I would like to transform a list like this:

l <- list(x = c(1, 2), y = c(3, 4, 5))

into a tibble like this:

 Name  Value 
 x      1
 x      2
 y      3
 y      4
 y      5

Answer 1

I think nothing will be easier than using the stack-function from base R:

df <- stack(l)

gives you a dataframe back:

> df
  values ind
1      1   x
2      2   x
3      3   y
4      4   y
5      5   y

Because you asked for tibble as output, you can do as_tibble(df) (from the tibble-package) to get that.

Or more directly: df <- as_tibble(stack(l)).

---

Another pure base R method:

df <- data.frame(ind = rep(names(l), lengths(l)), value = unlist(l), row.names = NULL)

which gives a similar result:

> df
  ind value
1   x     1
2   x     2
3   y     3
4   y     4
5   y     5

The row.names = NULL isn't necessarily needed but gives rownumbers as rownames.