The second argument to `call_function` should be a list (the args to
the function). Since `arr3` is iterable it is interpreting it as a
list of args and trying to treat each row as an argument to your call
(this is the reason it thinks you have 3 arguments). This should
work:
pc.call_function("struct_field", [arr3], pc.StructFieldOptions(indices=[0]))
Unfortunately, that evaluates the function immediately. If you want
to create an expression then you need some way to create a call and I
don't actually know how to do that. I can do something a little
hackish:
table = pa.Table.from_pydict({'values': arr3})
dataset = ds.dataset(table)
sf_call = ds.field('')._call('struct_field', [ds.field('values')],
pc.StructFieldOptions(indices=[0]))
dataset.to_table(filter=sf_call < 200)
However, I suspect there is probably a better way to create a call
object than `ds.field('')._call(...)`
On Wed, Apr 20, 2022 at 3:09 AM Partha Dutta <[email protected]> wrote:
>
> I'm trying to use the compute function struct_field in order to create an
> expression for dataset filtering. But running into an error. This is the code
> snippet:
>
> arr1 = pa.array([100, 200, 300])
> arr2 = pa.array([400, 500, 600])
> arr3 = pa.StructArray.from_arrays([arr1, arr2], ["one", "two"])
> e = pc.call_function("struct_field", arr3,
> pc.StructFieldOptions(indices=[0])) > 200
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> File "pyarrow/_compute.pyx", line 531, in pyarrow._compute.call_function
> File "pyarrow/_compute.pyx", line 330, in pyarrow._compute.Function.call
> File "pyarrow/error.pxi", line 143, in
> pyarrow.lib.pyarrow_internal_check_status
> File "pyarrow/error.pxi", line 99, in pyarrow.lib.check_status
> pyarrow.lib.ArrowInvalid: Function 'struct_field' accepts 1 arguments but
> attempted to look up kernel(s) with 3
>
> If I try to exclude the options, I get
> pyarrow.lib.ArrowInvalid: Function 'struct_field' cannot be called without
> options
>
> Any advice? I am using pyarrow 7.0.0
> --
> Partha Dutta
> [email protected]
