df <- convert_array(some_array_containing_a_geoarrow_col)
st_as_sfc(df$geometry)  # or s2::as_s2_geography(df$geometry), or something else

library(nanoarrow)

arrays <- lapply(
  list(1:5, 6:10, 11:13),
  as_nanoarrow_array
)

# A vctr can be created from any stream
(vctr <- as_nanoarrow_vctr(basic_array_stream(arrays)))
#> <nanoarrow_vctr int32[13]>
#>  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13

# Under the hood this is something like a factor() where levels are
# a list of arrays with cached offsets. This is like an Arrow ChunkedArray
str(vctr)
#> <nanoarrow_vctr int32[13]>
#> List of 3
#>  $ :<nanoarrow_array int32[5]>
#>   ..$ length    : int 5
#>   ..$ null_count: int 0
#>   ..$ offset    : int 0
#>   ..$ buffers   :List of 2
#>   .. ..$ :<nanoarrow_buffer validity<bool>[0][0 b]> ``
#>   .. ..$ :<nanoarrow_buffer data<int32>[5][20 b]> `1 2 3 4 5`
#>   ..$ dictionary: NULL
#>   ..$ children  : list()
#>  $ :<nanoarrow_array int32[5]>
#>   ..$ length    : int 5
#>   ..$ null_count: int 0
#>   ..$ offset    : int 0
#>   ..$ buffers   :List of 2
#>   .. ..$ :<nanoarrow_buffer validity<bool>[0][0 b]> ``
#>   .. ..$ :<nanoarrow_buffer data<int32>[5][20 b]> `6 7 8 9 10`
#>   ..$ dictionary: NULL
#>   ..$ children  : list()
#>  $ :<nanoarrow_array int32[3]>
#>   ..$ length    : int 3
#>   ..$ null_count: int 0
#>   ..$ offset    : int 0
#>   ..$ buffers   :List of 2
#>   .. ..$ :<nanoarrow_buffer validity<bool>[0][0 b]> ``
#>   .. ..$ :<nanoarrow_buffer data<int32>[3][12 b]> `11 12 13`
#>   ..$ dictionary: NULL
#>   ..$ children  : list()

# vctrs can be sliced:
head(vctr)
#> <nanoarrow_vctr int32[6]>
#> [1] 1 2 3 4 5 6

# ...and can live in a data.frame
head(tibble::tibble(x = vctr))
#> # A tibble: 6 × 1
#>   x         
#>   <nnrrw_vc>
#> 1 1         
#> 2 2         
#> 3 3         
#> 4 4         
#> 5 5         
#> 6 6

# They can be used as zero-copy conversion targets
array <- as_nanoarrow_array(1:5)
convert_array(array, nanoarrow_vctr())
#> <nanoarrow_vctr int32[5]>
#> [1] 1 2 3 4 5

# ...also works in a nested ptype
array <- as_nanoarrow_array(data.frame(x = 1:5))
convert_array(array, tibble::tibble(x = nanoarrow_vctr()))
#> # A tibble: 5 × 1
#>   x         
#>   <nnrrw_vc>
#> 1 1         
#> 2 2         
#> 3 3         
#> 4 4         
#> 5 5

# For nested list output, it will give a slice of the original array for
# each list item
array <- as_nanoarrow_array(
  list(1:5, 6:10, NULL, 11:13),
  schema = na_list(na_int32())
)

(lst_of <- convert_array(array, vctrs::list_of(nanoarrow_vctr())))
#> <list_of<nanoarrow_vctr>[4]>
#> [[1]]
#> <nanoarrow_vctr int32[5]>
#> [1] 1 2 3 4 5
#> 
#> [[2]]
#> <nanoarrow_vctr int32[5]>
#> [1]  6  7  8  9 10
#> 
#> [[3]]
#> NULL
#> 
#> [[4]]
#> <nanoarrow_vctr int32[3]>
#> [1] 11 12 13
for (i in seq_along(lst_of)) {
  array <- attr(lst_of[[i]], "chunks")[[1]]
  cat(sprintf("offset: %d, length: %d\n", array$offset, array$length))
}
#> offset: 0, length: 5
#> offset: 5, length: 5
#> offset: 10, length: 3