'Nested list to dataframe [using purrr + map]

I've looked at a lot of posts so I'm sorry if this is redundant, but was hoping to get some help flattening a nested list:

test <- list()
test <- c(
  list("A" = c(list("1"), list("2"), list("3"))), 
  list("B" = c(list("4"), list("5"), list("6")))
)

Desired Output

  name subcat
1    A      1
2    A      2
3    A      3
4    B      4
5    B      5
6    B      6

I'm struggling to write a nested for loop but I'd really like to use purrr or something more elegant to create a dataframe with two columns: the subcat column, and a repeated column for the name for each element in the list.

Any help appreciated, even just pointing me to similar posts - thanks!

rlistnestedpurrr


Solution 1:[1]

For these updated data you can try:

library(tidyverse)
enframe(test) %>%  unnest_longer(value)

# A tibble: 6 x 2
#  name  value
#  <chr> <chr>
#1 A     1    
#2 A     2    
#3 A     3    
#4 B     4    
#5 B     5    
#6 B     6

Solution 2:[2]

We can do this in base R with stack

stack(test)[2:1]
#   ind values
#1   A      1
#2   A      2
#3   A      3
#4   B      4
#5   B      5
#6   B      6

Or using unlist/data.frame

data.frame(name = rep(names(test), lengths(test)), val = unlist(test))

Sources

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Source: Stack Overflow

Solution Source
Solution 1 dhd
Solution 2 akrun

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