zhipeng93 commented on code in PR #145: URL: https://github.com/apache/flink-ml/pull/145#discussion_r953393891
########## flink-ml-lib/src/main/java/org/apache/flink/ml/feature/dct/DCT.java: ########## @@ -0,0 +1,138 @@ +/* + * 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. + */ + +package org.apache.flink.ml.feature.dct; + +import org.apache.flink.api.common.functions.MapFunction; +import org.apache.flink.api.java.typeutils.RowTypeInfo; +import org.apache.flink.ml.api.Transformer; +import org.apache.flink.ml.common.datastream.TableUtils; +import org.apache.flink.ml.linalg.DenseVector; +import org.apache.flink.ml.linalg.Vector; +import org.apache.flink.ml.linalg.Vectors; +import org.apache.flink.ml.linalg.typeinfo.VectorTypeInfo; +import org.apache.flink.ml.param.Param; +import org.apache.flink.ml.util.ParamUtils; +import org.apache.flink.ml.util.ReadWriteUtils; +import org.apache.flink.streaming.api.datastream.DataStream; +import org.apache.flink.table.api.Table; +import org.apache.flink.table.api.bridge.java.StreamTableEnvironment; +import org.apache.flink.table.api.internal.TableImpl; +import org.apache.flink.types.Row; +import org.apache.flink.util.Preconditions; + +import org.apache.commons.lang3.ArrayUtils; +import org.jtransforms.dct.DoubleDCT_1D; + +import java.io.IOException; +import java.util.HashMap; +import java.util.Map; +import java.util.function.BiConsumer; + +/** + * A Transformer that takes the 1D discrete cosine transform of a real vector. No zero padding is + * performed on the input vector. It returns a real vector of the same length representing the DCT. + * The return vector is scaled such that the transform matrix is unitary (aka scaled DCT-II). + * + * <p>See https://en.wikipedia.org/wiki/Discrete_cosine_transform#DCT-II(DCT-II in Discrete cosine + * transform). + */ +public class DCT implements Transformer<DCT>, DCTParams<DCT> { + private final Map<Param<?>, Object> paramMap = new HashMap<>(); + + public DCT() { + ParamUtils.initializeMapWithDefaultValues(paramMap, this); + } + + @Override + public Table[] transform(Table... inputs) { + Preconditions.checkArgument(inputs.length == 1); + + StreamTableEnvironment tEnv = + (StreamTableEnvironment) ((TableImpl) inputs[0]).getTableEnvironment(); + + RowTypeInfo inputTypeInfo = TableUtils.getRowTypeInfo(inputs[0].getResolvedSchema()); + RowTypeInfo outputTypeInfo = + new RowTypeInfo( + ArrayUtils.addAll(inputTypeInfo.getFieldTypes(), VectorTypeInfo.INSTANCE), Review Comment: It seems that the output is always a dense vector. How about make it `DenseVectorTypeInfo.INSTANCE`? ########## flink-ml-lib/src/main/java/org/apache/flink/ml/feature/dct/DCT.java: ########## @@ -0,0 +1,138 @@ +/* + * 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. + */ + +package org.apache.flink.ml.feature.dct; + +import org.apache.flink.api.common.functions.MapFunction; +import org.apache.flink.api.java.typeutils.RowTypeInfo; +import org.apache.flink.ml.api.Transformer; +import org.apache.flink.ml.common.datastream.TableUtils; +import org.apache.flink.ml.linalg.DenseVector; +import org.apache.flink.ml.linalg.Vector; +import org.apache.flink.ml.linalg.Vectors; +import org.apache.flink.ml.linalg.typeinfo.VectorTypeInfo; +import org.apache.flink.ml.param.Param; +import org.apache.flink.ml.util.ParamUtils; +import org.apache.flink.ml.util.ReadWriteUtils; +import org.apache.flink.streaming.api.datastream.DataStream; +import org.apache.flink.table.api.Table; +import org.apache.flink.table.api.bridge.java.StreamTableEnvironment; +import org.apache.flink.table.api.internal.TableImpl; +import org.apache.flink.types.Row; +import org.apache.flink.util.Preconditions; + +import org.apache.commons.lang3.ArrayUtils; +import org.jtransforms.dct.DoubleDCT_1D; + +import java.io.IOException; +import java.util.HashMap; +import java.util.Map; +import java.util.function.BiConsumer; + +/** + * A Transformer that takes the 1D discrete cosine transform of a real vector. No zero padding is + * performed on the input vector. It returns a real vector of the same length representing the DCT. + * The return vector is scaled such that the transform matrix is unitary (aka scaled DCT-II). + * + * <p>See https://en.wikipedia.org/wiki/Discrete_cosine_transform#DCT-II(DCT-II in Discrete cosine + * transform). + */ +public class DCT implements Transformer<DCT>, DCTParams<DCT> { + private final Map<Param<?>, Object> paramMap = new HashMap<>(); + + public DCT() { + ParamUtils.initializeMapWithDefaultValues(paramMap, this); + } + + @Override + public Table[] transform(Table... inputs) { + Preconditions.checkArgument(inputs.length == 1); + + StreamTableEnvironment tEnv = + (StreamTableEnvironment) ((TableImpl) inputs[0]).getTableEnvironment(); + + RowTypeInfo inputTypeInfo = TableUtils.getRowTypeInfo(inputs[0].getResolvedSchema()); + RowTypeInfo outputTypeInfo = + new RowTypeInfo( + ArrayUtils.addAll(inputTypeInfo.getFieldTypes(), VectorTypeInfo.INSTANCE), + ArrayUtils.addAll(inputTypeInfo.getFieldNames(), getOutputCol())); + + DataStream<Row> stream = + tEnv.toDataStream(inputs[0]) + .map(new DCTFunction(getInputCol(), getInverse()), outputTypeInfo); + + return new Table[] {tEnv.fromDataStream(stream)}; + } + + /** + * A {@link MapFunction} that contains the main logic to perform discrete cosine transformation. + */ + private static class DCTFunction implements MapFunction<Row, Row> { + private final String inputCol; + + private final boolean isInverse; + + private BiConsumer<double[], Boolean> dctTransformer; + + private long previousVectorSize; + + private DCTFunction(String inputCol, boolean isInverse) { + this.inputCol = inputCol; + this.isInverse = isInverse; + this.dctTransformer = null; + this.previousVectorSize = -1; + } + + @Override + public Row map(Row row) throws Exception { + Vector vector = row.getFieldAs(inputCol); + + if (dctTransformer == null || previousVectorSize != vector.size()) { Review Comment: nit: `dctTransformer == null` seems unnecessary. ########## flink-ml-lib/src/main/java/org/apache/flink/ml/feature/dct/DCTParams.java: ########## @@ -0,0 +1,46 @@ +/* + * 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. + */ + +package org.apache.flink.ml.feature.dct; + +import org.apache.flink.ml.common.param.HasInputCol; +import org.apache.flink.ml.common.param.HasOutputCol; +import org.apache.flink.ml.param.BooleanParam; +import org.apache.flink.ml.param.Param; + +/** + * Params for {@link DCT}. + * + * @param <T> The class type of this instance. + */ +public interface DCTParams<T> extends HasInputCol<T>, HasOutputCol<T> { + Param<Boolean> INVERSE = + new BooleanParam( + "inverse", + "Whether to perform the inverse DCT (true) or forward DCT (false).", + false); + + default boolean getInverse() { + return get(INVERSE); + } + + default T setInverse(boolean value) { + set(INVERSE, value); Review Comment: nit: could be `return set(INVERSE, value);` -- This is an automated message from the Apache Git Service. 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