Converting list of dataframes into a sf object in R

I am trying to convert a list of sfc dataframes into a single sf object with geometry per row.

Somehow I managed to convert it to a sf dataframe but I have a weird sf object. In the environment panel, it says there is two columns but when I open the variable, it has three columns: geometry and geometry.1.

This is my R code.

# list of dataframes into an 'sf' dataframe
polygons <- list()

for (i in 1:length(reachable_nodes_for_pois_list)) {
  polygon <- reachable_nodes_for_pois_list[[i]][[1]]
  polygons[[i]] <- polygon
}


iso_polygons <- sf::st_sfc(do.call(rbind, polygons))


sf_df <- sf::st_sf(geometry = iso_polygons)

amenity_isochrone <- cbind(iso_points$nodeID, sf_df)
st_crs(amenity_isochrone) <- 27700

Could anyone help? Thank you!

Solution

Try do.call(rbind, reachable_nodes_for_pois_list) or dplyr::bind_rows(reachable_nodes_for_pois_list)

That input structure is somewhat peculiar, took a few tries to construct something similar:

library(dplyr)
library(sf)
reachable_nodes_for_pois_list <- st_read(system.file("shape/nc.shp", package="sf"), 
                                         quiet = TRUE) %>% 
  st_cast("POLYGON") %>% 
  select(polygons = geometry) %>% 
  slice_head(n = 8) %>% 
  split(1:8) %>% 
  unname()

str(reachable_nodes_for_pois_list[1])
#> List of 1
#>  $ :Classes 'sf' and 'data.frame':   1 obs. of  1 variable:
#>   ..$ polygons:sfc_POLYGON of length 1; first list element: List of 1
#>   .. ..$ : num [1:27, 1:2] -81.5 -81.5 -81.6 -81.6 -81.7 ...
#>   .. ..- attr(*, "class")= chr [1:3] "XY" "POLYGON" "sfg"
#>   ..- attr(*, "sf_column")= chr "polygons"
#>   ..- attr(*, "agr")= Factor w/ 3 levels "constant","aggregate",..: 
#>   .. ..- attr(*, "names")= chr(0)

Though bind_rows() / do.call(rbind, ...) will handle it just fine:

bind_rows(reachable_nodes_for_pois_list)
#> Simple feature collection with 8 features and 0 fields
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -81.74107 ymin: 36.07282 xmax: -75.77316 ymax: 36.58965
#> Geodetic CRS:  NAD27
#>                         polygons
#> 1 POLYGON ((-81.47276 36.2343...
#> 2 POLYGON ((-81.23989 36.3653...
#> 3 POLYGON ((-80.45634 36.2425...
#> 4 POLYGON ((-76.00897 36.3196...
#> 5 POLYGON ((-76.02717 36.5567...
#> 6 POLYGON ((-75.90199 36.5562...
#> 7 POLYGON ((-77.21767 36.2409...
#> 8 POLYGON ((-76.74506 36.2339...

^{Created on 2023-07-07 with reprex v2.0.2}