jiangxin369 commented on code in PR #214: URL: https://github.com/apache/flink-ml/pull/214#discussion_r1113895887
########## flink-ml-servable-core/src/main/java/org/apache/flink/ml/servable/api/DataFrame.java: ########## @@ -0,0 +1,120 @@ +/* + * 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.servable.api; + +import org.apache.flink.annotation.PublicEvolving; +import org.apache.flink.ml.servable.types.DataType; + +import java.util.Iterator; +import java.util.List; + +/** + * A DataFrame consists of some number of rows, each of which has the same list of column names and + * data types. + * + * <p>All values in a column must have the same data type: integer, float, string etc. + */ +@PublicEvolving +public class DataFrame { + + private final List<String> columnNames; + private final List<DataType> dataTypes; + private final List<Row> rows; + + public DataFrame(List<String> columnNames, List<DataType> dataTypes, List<Row> rows) { + int numColumns = columnNames.size(); + if (dataTypes.size() != numColumns) { + throw new IllegalArgumentException( + "The number of data types is different from the number of column names."); + } + for (Row row : rows) { + if (row.size() != numColumns) { + throw new IllegalArgumentException( + "The number of values in some row is different from the number of column names"); + } + } + + this.columnNames = columnNames; + this.dataTypes = dataTypes; + this.rows = rows; + } + + /** Returns a list of the names of all the columns in this DataFrame. */ + public List<String> getColumnNames() { + return columnNames; + } + + /** + * Returns the index of the column with the given name. + * + * @throws IllegalArgumentException if the column is not present in this table + */ + public int getIndex(String name) { + for (int i = 0; i < columnNames.size(); i++) { + if (columnNames.get(i).equals(name)) { + return i; + } + } + throw new IllegalArgumentException("Failed to find the column with the given name."); + } + + /** + * Returns the data type of the column with the given name. + * + * @throws IllegalArgumentException if the column is not present in this table + */ + public DataType getDataType(String name) { + int index = getIndex(name); + return dataTypes.get(index); + } + + /** + * Adds to this DataFrame a column with the given name, data type, and values. + * + * @throws IllegalArgumentException if the number of values is different from the number of + * rows. + */ + public DataFrame addColumn(String columnName, DataType dataType, List<Object> values) { + if (values.size() != rows.size()) { + throw new RuntimeException( + "The number of values is different from the number of rows."); + } + columnNames.add(columnName); + dataTypes.add(dataType); Review Comment: The benefit of doing this check is that we can give users a more intuitive error message instead of `UnsupportedOperationException`, but I agree it is not necessary. Adding docs also addresses my concern, but you need to change the `should be immutable` to `should be mutable`and also add such docs for `Row` constructor. -- 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. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
