Hi Li,
I've faced this issue before, and I ended up using a generic ArrayBuilder,
for example:
```cpp
auto type = int32();
std::vector<std::shared_ptr<Scalar>> scalars = {MakeScalar(1),
MakeScalar(2)};
ARROW_ASSIGN_OR_RAISE(std::unique_ptr<ArrayBuilder> builder,
MakeBuilder(type));
ARROW_RETURN_NOT_OK(builder->AppendScalars(scalars));
ARROW_ASSIGN_OR_RAISE(auto arr, builder->Finish());
```
Best,
Jin
On Fri, Jun 16, 2023 at 5:23 AM Li Jin <ice.xell...@gmail.com> wrote:
> Hi,
>
> I find myself in need of a function to turn a vector of Scalar to an Array
> of the same datatype. The data type is known at the runtime. e.g.
>
> shared_ptr<ArrayData> concat_scalars(vector<shared_ptr<Scalar> values.
> shared_ptr<DataType> type);
>
> I wonder if I need to use sth like Scalar::Accept(ScalarVisitor*) or is
> there an easier/better way to achieve this?
>
> For context, I am trying to implement UDF support for hash aggregation,
> each UDF invocation will give me back one Scalar (for each group), and I
> need to concat them in the HashAggregateKernel finalize method. So
> performance is not a large concern here, time in the UDF would likely
> dominate the total runtime.
>
> Thanks!
> Li
>
