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https://issues.apache.org/jira/browse/ARROW-1559?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16234450#comment-16234450
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ASF GitHub Bot commented on ARROW-1559:
---------------------------------------
xhochy commented on a change in pull request #1266: WIP: ARROW-1559: Add unique
kernel
URL: https://github.com/apache/arrow/pull/1266#discussion_r148330119
##########
File path: cpp/src/arrow/compute/hash_kernels.cc
##########
@@ -0,0 +1,131 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#include "arrow/compute/hash_kernels.h"
+
+#include <sstream>
+
+#include "arrow/builder.h"
+#include "arrow/compute/context.h"
+#include "arrow/compute/kernel.h"
+
+namespace arrow {
+namespace compute {
+
+namespace {
+
+template <typename DataType>
+class UniqueKernel : public UnaryKernel {
+ Status Call(FunctionContext* ctx, const Array& input,
+ std::shared_ptr<ArrayData>* out) override {
+ if (!unique_builder) {
+ unique_builder =
+ std::make_shared<UniqueBuilder<DataType>>(input.type(),
ctx->memory_pool());
+ }
+
+ RETURN_NOT_OK(unique_builder->AppendArray(input));
+
+ if (out) {
+ RETURN_NOT_OK(unique_builder->FinishInternal(out));
+ unique_builder.reset();
+ }
+
+ return Status::OK();
+ }
+
+ private:
+ std::shared_ptr<UniqueBuilder<DataType>> unique_builder;
+};
+}
+
+#define UNIQUE_FUNCTION_CASE(InType) \
+ case InType::type_id: \
+ *kernel = std::unique_ptr<UnaryKernel>(new UniqueKernel<InType>()); \
+ break
+
+Status GetUniqueFunction(const DataType& in_type,
std::unique_ptr<UnaryKernel>* kernel) {
+ switch (in_type.id()) {
+ // UNIQUE_FUNCTION_CASE(NullType);
+ // UNIQUE_FUNCTION_CASE(BooleanType);
+ UNIQUE_FUNCTION_CASE(UInt8Type);
+ UNIQUE_FUNCTION_CASE(Int8Type);
+ UNIQUE_FUNCTION_CASE(UInt16Type);
+ UNIQUE_FUNCTION_CASE(Int16Type);
+ UNIQUE_FUNCTION_CASE(UInt32Type);
+ UNIQUE_FUNCTION_CASE(Int32Type);
+ UNIQUE_FUNCTION_CASE(UInt64Type);
+ UNIQUE_FUNCTION_CASE(Int64Type);
+ UNIQUE_FUNCTION_CASE(FloatType);
+ UNIQUE_FUNCTION_CASE(DoubleType);
+ UNIQUE_FUNCTION_CASE(Date32Type);
+ UNIQUE_FUNCTION_CASE(Date64Type);
+ UNIQUE_FUNCTION_CASE(Time32Type);
+ UNIQUE_FUNCTION_CASE(Time64Type);
+ UNIQUE_FUNCTION_CASE(TimestampType);
+ UNIQUE_FUNCTION_CASE(BinaryType);
+ UNIQUE_FUNCTION_CASE(StringType);
+ UNIQUE_FUNCTION_CASE(FixedSizeBinaryType);
+ default:
+ break;
+ }
+
+ if (*kernel == nullptr) {
+ std::stringstream ss;
+ ss << "No unique implemented for " << in_type.ToString();
+ return Status::NotImplemented(ss.str());
+ }
+
+ return Status::OK();
+}
+
+Status Unique(FunctionContext* ctx, const Array& array,
std::shared_ptr<Array>* out) {
+ // Dynamic dispatch to obtain right cast function
+ std::unique_ptr<UnaryKernel> func;
+ RETURN_NOT_OK(GetUniqueFunction(*array.type(), &func));
+
+ std::shared_ptr<ArrayData> out_data;
+ RETURN_NOT_OK(func->Call(ctx, array, &out_data));
+ *out = MakeArray(out_data);
+ return Status::OK();
+}
+
+Status Unique(FunctionContext* ctx, const ChunkedArray& array,
+ std::shared_ptr<Array>* out) {
+ // Dynamic dispatch to obtain right cast function
+ std::unique_ptr<UnaryKernel> func;
+ RETURN_NOT_OK(GetUniqueFunction(*array.type(), &func));
+
+ // Call the kernel without out_data on all but the last chunk
+ for (int i = 0; i < (array.num_chunks() - 1); i++) {
+ RETURN_NOT_OK(func->Call(ctx, *array.chunk(i), nullptr));
+ }
+
+ std::shared_ptr<ArrayData> out_data;
+ // The array has a large chunk, call the kernel and retrieve the result.
+ RETURN_NOT_OK(func->Call(ctx, *array.chunk(array.num_chunks() - 1),
&out_data));
+ *out = MakeArray(out_data);
+
+ return Status::OK();
+}
+
+Status Unique(FunctionContext* context, const Column& array,
+ std::shared_ptr<Array>* out) {
+ return Unique(context, *array.data(), out);
+}
Review comment:
This also sounds fine to me. In the end, we would need to have these three
levels for all kernels (Array, ChunkedArray, Column) which would mean a lot of
pass-through methods.
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> [C++] Kernel implementations for "unique" (compute distinct elements of array)
> ------------------------------------------------------------------------------
>
> Key: ARROW-1559
> URL: https://issues.apache.org/jira/browse/ARROW-1559
> Project: Apache Arrow
> Issue Type: New Feature
> Components: C++
> Reporter: Wes McKinney
> Assignee: Uwe L. Korn
> Priority: Major
> Labels: Analytics, pull-request-available
> Fix For: 0.8.0
>
>
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