walterddr commented on a change in pull request #9355: [FLINK-13577][ml] Add an util class to build result row and generate … URL: https://github.com/apache/flink/pull/9355#discussion_r344502293
########## File path: flink-ml-parent/flink-ml-lib/src/main/java/org/apache/flink/ml/common/utils/OutputColsHelper.java ########## @@ -0,0 +1,186 @@ +/* + * 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.common.utils; + +import org.apache.flink.api.common.typeinfo.TypeInformation; +import org.apache.flink.table.api.TableSchema; +import org.apache.flink.types.Row; + +import org.apache.commons.lang3.ArrayUtils; + +import java.io.Serializable; +import java.util.ArrayList; +import java.util.Arrays; +import java.util.HashSet; + +/** + * Util for generating output schema when doing prediction or transformation. + * + * <p>Input: + * 1) Schema of input data being predicted or transformed. + * 2) Output column names of the prediction/transformation operator. + * 3) Output column types of the prediction/transformation operator. + * 4) Reserved column names, which is a subset of input data's column names that we want to preserve. + * + * <p>Output: + * 1）The result data schema. The result data is a combination of the preserved columns and the operator's + * output columns. + * + * <p>Several rules are followed: + * 1) If reserved columns are not given, then all columns of input data is reserved. + * 2）The reserved columns are arranged ahead of the operator's output columns in the final output. + * 3) If some of the reserved column names overlap with those of operator's output columns, then the operator's + * output columns override the conflicting reserved columns. + * + * <p>For example, if we have input data schema of ["id":INT, "f1":FLOAT, "f2":DOUBLE], and the operator outputs + * a column "label" with type STRING, and we want to preserve the column "id", then we get the output + * schema of ["id":INT, "label":STRING]. + */ +public class OutputColsHelper implements Serializable { Review comment: I would suggest putting this as part of the Javadoc --> Unlike Scala Java has no module private modifier like `private[flink]`, but it is still good to point out IMO ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
