Extracting data from a list of lists into its own `data.frame` with `purrr`

Question

Representative sample data (list of lists):

l <- list(structure(list(a = -1.54676469632688, b = \"s\", c = \"T\", 
d = structure(list(id = 5L, label = \"U         


        

Answer 1

You can do this in three steps, first pulling out d, then binding the rows within each element of d, and then binding everything into a single object.

I use bind_rows from dplyr for the within-list row binding. map_df does the final row binding.

library(purrr)
library(dplyr)

l %>%
    map("d") %>%
    map_df(bind_rows)

This is also equivalent:

map_df(l, ~bind_rows(.x[["d"]] ) )

The result looks like:

# A tibble: 12 x 5
      id          label                 link      score externalId
                                         
 1     5           Utah          Asia/Anadyr -0.2110459         NA
 2     8 South Carolina       Pacific/Wallis  0.5265409  -6.743544
 3     9       Nebraska America/Scoresbysund  0.2508955  16.425747
 4     8        Georgia         America/Nome  0.5264941   7.915836
 5     2     Washington     America/Shiprock -0.5551864  15.068666
 6     6   North Dakota            Universal  1.0316830         NA
 7     1  New Hampshire      America/Cordoba  1.2158206   9.727642
 8     1         Alaska        Asia/Istanbul -0.2318326         NA
 9     4   Pennsylvania Africa/Dar_es_Salaam  0.5902453         NA
10     3       Delaware       Asia/Samarkand  0.6955771  15.236482
11     4   North Dakota      America/Tortola  1.0306027  -7.216669
12     9       Nebraska      America/Ojinaga -1.1139800  -8.451451