flink-tests/src/test/java/org/apache/flink/test/util/PointFormatter.java

/*
 * 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.test.util;

import org.apache.flink.api.java.io.TextOutputFormat.TextFormatter;
import org.apache.flink.api.java.tuple.Tuple2;

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;

/**
 * Writes records that contain an id and a CoordVector. The output format is line-based, i.e. one
 * record is written to a line and terminated with '\n'. Within a line the first '|' character
 * separates the id from the CoordVector. The vector consists of a vector of decimals. The decimals
 * are separated by '|'. The is is the id of a data point or cluster center and the vector the
 * corresponding position (coordinate vector) of the data point or cluster center. Example line:
 * "42|23.23|52.57|74.43| Id: 42 Coordinate vector: (23.23, 52.57, 74.43)
 */
public class PointFormatter implements TextFormatter<Tuple2<Integer, CoordVector>> {
    private static final long serialVersionUID = 1L;

    private final DecimalFormat df = new DecimalFormat("####0.00");
    private final StringBuilder line = new StringBuilder();

    public PointFormatter() {
        DecimalFormatSymbols dfSymbols = new DecimalFormatSymbols();
        dfSymbols.setDecimalSeparator('.');
        this.df.setDecimalFormatSymbols(dfSymbols);
    }

    @Override
    public String format(Tuple2<Integer, CoordVector> value) {
        line.setLength(0);

        line.append(value.f0);

        for (double coord : value.f1.getCoordinates()) {
            line.append('|');
            line.append(df.format(coord));
        }
        line.append('|');

        return line.toString();
    }
}