lidavidm commented on a change in pull request #10390:
URL: https://github.com/apache/arrow/pull/10390#discussion_r643232604
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File path: cpp/src/arrow/compute/kernels/scalar_arithmetic.cc
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@@ -516,6 +564,190 @@ std::shared_ptr<ScalarFunction>
MakeUnarySignedArithmeticFunctionNotNull(
return func;
}
+using MinMaxState = OptionsWrapper<ElementWiseAggregateOptions>;
+
+// Implement a variadic scalar min/max kernel.
+template <typename OutType, typename Op>
+struct ScalarMinMax {
+ using OutValue = typename GetOutputType<OutType>::T;
+
+ static void ExecScalar(const ExecBatch& batch,
+ const ElementWiseAggregateOptions& options, Scalar*
out) {
+ // All arguments are scalar
+ OutValue value{};
+ bool valid = false;
+ for (const auto& arg : batch.values) {
+ // Ignore non-scalar arguments so we can use it in the
mixed-scalar-and-array case
+ if (!arg.is_scalar()) continue;
+ const auto& scalar = *arg.scalar();
+ if (!scalar.is_valid) {
+ if (options.skip_nulls) continue;
+ out->is_valid = false;
+ return;
+ }
+ if (!valid) {
+ value = UnboxScalar<OutType>::Unbox(scalar);
+ valid = true;
+ } else {
+ value = Op::Call(value, UnboxScalar<OutType>::Unbox(scalar));
+ }
+ }
+ out->is_valid = valid;
+ if (valid) {
+ BoxScalar<OutType>::Box(value, out);
+ }
+ }
+
+ static Status Exec(KernelContext* ctx, const ExecBatch& batch, Datum* out) {
+ const ElementWiseAggregateOptions& options = MinMaxState::Get(ctx);
+ const auto descrs = batch.GetDescriptors();
+ const size_t scalar_count =
+ static_cast<size_t>(std::count_if(batch.values.begin(),
batch.values.end(),
+ [](const Datum& d) { return
d.is_scalar(); }));
+ if (scalar_count == batch.values.size()) {
+ ExecScalar(batch, options, out->scalar().get());
+ return Status::OK();
+ }
+
+ ArrayData* output = out->mutable_array();
Review comment:
This works quite well except in the case that we have a singular NaN
array argument (`element_wise_min([NaN])`) - in which case we want to emit
`NaN` not the antiextreme.
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