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CalculateAverage_abfrmblr.java
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CalculateAverage_abfrmblr.java
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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.util.concurrent.*;
import java.util.stream.Stream;
import static java.nio.file.Files.lines;
import static java.nio.file.Paths.*;
public class CalculateAverage_abfrmblr {
private static final String FILE = "./measurements.txt";
private static record Stats (double min, double max, double mean, long count) {
@Override
public String toString() {
return round(min) + "/" + round(mean) + "/" + round(max);
}
private double round(double value) {
return Math.round(value * 10.0) / 10.0;
}
}
private static record MeasurementTuple (String station, double temp) {
public MeasurementTuple (String[] values) {
this(values[0], Double.parseDouble(values[1]));
}
}
public static void main(String[] args) throws IOException {
Stream<String> lines = lines(get(FILE));
ConcurrentMap<String, Stats> aggregatedStats = new ConcurrentSkipListMap<>();
lines.parallel().forEach(s -> {
MeasurementTuple tuple = new MeasurementTuple(s.split(";"));
aggregatedStats.compute(tuple.station(), (s1, stats) -> {
if (stats == null) {
return new Stats(tuple.temp, tuple.temp, tuple.temp, 1L);
}
else {
long latestCount = stats.count + 1;
double min = Math.min(stats.min, tuple.temp);
double max = Math.max(stats.max, tuple.temp);
double mean = ((stats.mean * stats.count) + tuple.temp) / latestCount;
return new Stats(min, max, mean, latestCount);
}
});
});
System.out.println(aggregatedStats);
}
}