Most common R vector types are converted automatically to a suitable
Arrow data type without the need for an extension type. For
vector types whose conversion is not suitably handled by default, you can
create a vctrs_extension_array(), which passes vctrs::vec_data() to
Array$create() and calls vctrs::vec_restore() when the Array is
converted back into an R vector.
Usage
vctrs_extension_array(x, ptype = vctrs::vec_ptype(x), storage_type = NULL)
vctrs_extension_type(x, storage_type = infer_type(vctrs::vec_data(x)))Arguments
- x
A vctr (i.e.,
vctrs::vec_is()returnsTRUE).- ptype
A
vctrs::vec_ptype(), which is usually a zero-length version of the object with the appropriate attributes set. This value will be serialized usingserialize(), so it should not refer to any R object that can't be saved/reloaded.- storage_type
The data type of the underlying storage array.
Value
vctrs_extension_array()returns an ExtensionArray instance with avctrs_extension_type().vctrs_extension_type()returns an ExtensionType instance for the extension name "arrow.r.vctrs".
Examples
(array <- vctrs_extension_array(as.POSIXlt("2022-01-02 03:45", tz = "UTC")))
#> ExtensionArray
#> <POSIXlt of length 0>
#> -- is_valid: all not null
#> -- child 0 type: double
#> [
#> 0
#> ]
#> -- child 1 type: int32
#> [
#> 45
#> ]
#> -- child 2 type: int32
#> [
#> 3
#> ]
#> -- child 3 type: int32
#> [
#> 2
#> ]
#> -- child 4 type: int32
#> [
#> 0
#> ]
#> -- child 5 type: int32
#> [
#> 122
#> ]
#> -- child 6 type: int32
#> [
#> 0
#> ]
#> -- child 7 type: int32
#> [
#> 1
#> ]
#> -- child 8 type: int32
#> [
#> 0
#> ]
#> -- child 9 type: string
#> [
#> "UTC"
#> ]
#> -- child 10 type: int32
#> [
#> 0
#> ]
array$type
#> VctrsExtensionType
#> POSIXlt of length 0
as.vector(array)
#> [1] "2022-01-02 03:45:00 UTC"
temp_feather <- tempfile()
write_feather(arrow_table(col = array), temp_feather)
read_feather(temp_feather)
#> # A tibble: 1 x 1
#> col
#> <dttm>
#> 1 2022-01-02 03:45:00
unlink(temp_feather)