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/*
* Copyright 2023 The original authors
*
* Licensed 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 dev.morling.onebrc;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.DoubleSummaryStatistics;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;
import static java.lang.Double.parseDouble;
import static java.lang.String.format;
import static java.util.stream.Collectors.summarizingDouble;
public class CalculateAverage_santanu {
private static final String DATA_FILE = "./measurements.txt";
private static final String PRINT_FORMAT = "%s=%.1f/%.1f/%.1f";
public static void main(String[] args) throws IOException {
Map<String, DoubleSummaryStatistics> summaryStatisticsMap = processMeasurements();
printResults(summaryStatisticsMap);
}
private static final Function<String, StationMeasurementPair> stationMeasurements = row -> {
int splitPosition = row.indexOf(";");
return new StationMeasurementPair(row.substring(0, splitPosition), parseDouble(row.substring(splitPosition + 1)));
};
private static Map<String, DoubleSummaryStatistics> processMeasurements() throws IOException {
return Files.lines(Path.of(DATA_FILE)).map(stationMeasurements).parallel()
.collect(Collectors.groupingBy(
StationMeasurementPair::station, summarizingDouble(StationMeasurementPair::measurement)));
}
private static void printResults(Map<String, DoubleSummaryStatistics> collect) {
String result = collect.entrySet().parallelStream().sorted(Map.Entry.comparingByKey()).map(s -> format(PRINT_FORMAT, s.getKey(),
s.getValue().getMin(), s.getValue().getAverage(), s.getValue().getMax())).collect(Collectors.joining(", "));
System.out.println("{" + result + "}");
}
private record StationMeasurementPair(String station, Double measurement) {
}
}
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