How to convert list of lists of vectors to a dataframe

Question

I have a set of data that is a list of lists of vectors of coordinates that are separated into two groups

geom                                                             group
list(list(c(43, 43, 40, 40, 43, 10, 13, 13, 10, 10), list(...     1 
list(c(95, 100, 100, 95, 95, -12, -12, -19, -19, -12)             2

I would like to convert this into a dataframe that looks like:

Longitude  Latitude  Group
 43         10       1
 43         13       1

etc.

To reproduce my data

structure(list(geom = structure(list(structure(list(list(structure(c(43, 
43, 40, 40, 43, 10, 13, 13, 10, 10), .Dim = c(5L, 2L))), list(
structure(c(23, 23, 20, 20, 23, 10, 13, 13, 10, 10), .Dim = c(5L, 
2L))), list(structure(c(25, 25, 38, 25, 10, 10.3, 10.3, 10
), .Dim = c(4L, 2L)))), class = c("XY", "MULTIPOLYGON", "sfg"
)), structure(list(structure(c(95, 100, 100, 95, 95, -12, -12, 
-19, -19, -12), .Dim = c(5L, 2L))), class = c("XY", "POLYGON", 
"sfg"))), n_empty = 0L, precision = 0, crs = structure(list(input = "EPSG:4326", 
wkt = "GEOGCS[\"WGS 84\",\n    DATUM[\"WGS_1984\",\n        SPHEROID[\"WGS 
84\",6378137,298.257223563,\n            AUTHORITY[\"EPSG\",\"7030\"]],\n        
AUTHORITY[\"EPSG\",\"6326\"]],\n    PRIMEM[\"Greenwich\",0,\n        
AUTHORITY[\"EPSG\",\"8901\"]],\n    UNIT[\"degree\",0.0174532925199433,\n        
AUTHORITY[\"EPSG\",\"9122\"]],\n    AUTHORITY[\"EPSG\",\"4326\"]]"), class = "crs"), class = 
c("sfc_GEOMETRY", 
"sfc"), bbox = structure(c(xmin = 20, ymin = -19, xmax = 100, 
ymax = 13), class = "bbox"), classes = c("MULTIPOLYGON", "POLYGON"
)), group = 1:2), row.names = 1:2, sf_column = "geom", agr = structure(c(group = 
NA_integer_), class = "factor", .Label = c("constant", 
"aggregate", "identity")), class = c("sf", "data.frame"))

Example of data split into more than two groups, in this case the data is split into three groups:

structure(list(geom = 
structure(list(structure(list(list(structure(c(43, 
43, 40, 40, 43, 10, 13, 13, 10, 10), .Dim = c(5L, 2L))), list(
structure(c(23, 23, 20, 20, 23, 10, 13, 13, 10, 10), .Dim = c(5L, 
2L))), list(structure(c(25, 25, 38, 25, 10, 10.3, 10.3, 10
), .Dim = c(4L, 2L)))), class = c("XY", "MULTIPOLYGON", "sfg"
)), structure(list(structure(c(60, 60, 80, 80, 60, 6, 5.7, 5.7, 
6, 6), .Dim = c(5L, 2L))), class = c("XY", "POLYGON", "sfg")), 
structure(list(structure(c(95, 100, 100, 95, 95, -12, -12, 
-19, -19, -12), .Dim = c(5L, 2L))), class = c("XY", "POLYGON", 
"sfg"))), n_empty = 0L, precision = 0, crs = structure(list(
input = "EPSG:4326", wkt = "GEOGCS[\"WGS 84\",\n    
DATUM[\"WGS_1984\",\n        SPHEROID[\"WGS 
84\",6378137,298.257223563,\n            
AUTHORITY[\"EPSG\",\"7030\"]],\n        
AUTHORITY[\"EPSG\",\"6326\"]],\n    PRIMEM[\"Greenwich\",0,\n        
AUTHORITY[\"EPSG\",\"8901\"]],\n    
UNIT[\"degree\",0.0174532925199433,\n        
AUTHORITY[\"EPSG\",\"9122\"]],\n    AUTHORITY[\"EPSG\",\"4326\"]]"), 
class = "crs"), class = c("sfc_GEOMETRY", 
"sfc"), bbox = structure(c(xmin = 20, ymin = -19, xmax = 100, 
ymax = 13), class = "bbox"), classes = c("MULTIPOLYGON", "POLYGON", 
"POLYGON")), group = 1:3), row.names = c(NA, 3L), sf_column = "geom", 
agr = structure(c(group = NA_integer_), class = "factor", .Label = 
c("constant", 
"aggregate", "identity")), class = c("sf", "data.frame"))

Answer 1

You can try this base R solution, where List is the dput() you included in the question:

#Empty list
Mylist <- list()
#Loop
for(i in 1:dim(List)[1])
{
  Mylist[[i]] <- do.call(rbind,lapply(List$geom[[i]],data.frame))
  Mylist[[i]]$Group <- List$group[[i]]  
}
#Now bind all
DF <- do.call(rbind,Mylist)

Output:

    X1    X2 Group
1   43  10.0     1
2   43  13.0     1
3   40  13.0     1
4   40  10.0     1
5   43  10.0     1
6   23  10.0     1
7   23  13.0     1
8   20  13.0     1
9   20  10.0     1
10  23  10.0     1
11  25  10.0     1
12  25  10.3     1
13  38  10.3     1
14  25  10.0     1
15  95 -12.0     2
16 100 -12.0     2
17 100 -19.0     2
18  95 -19.0     2
19  95 -12.0     2

Names are standard based on your data, so you can rename as you want (X1 and X2).

Also for more groups:

    X1    X2 Group
1   43  10.0     1
2   43  13.0     1
3   40  13.0     1
4   40  10.0     1
5   43  10.0     1
6   23  10.0     1
7   23  13.0     1
8   20  13.0     1
9   20  10.0     1
10  23  10.0     1
11  25  10.0     1
12  25  10.3     1
13  38  10.3     1
14  25  10.0     1
15  60   6.0     2
16  60   5.7     2
17  80   5.7     2
18  80   6.0     2
19  60   6.0     2
20  95 -12.0     3
21 100 -12.0     3
22 100 -19.0     3
23  95 -19.0     3
24  95 -12.0     3