92 lines
3.2 KiB
Java
92 lines
3.2 KiB
Java
/*
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* Copyright 2023 The original authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package dev.morling.onebrc;
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import static java.util.stream.Collectors.*;
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import java.io.IOException;
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import java.nio.file.Files;
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import java.nio.file.Paths;
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import java.util.Map;
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import java.util.TreeMap;
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import java.util.stream.Collector;
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public class CalculateAverage {
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private static final String FILE = "./measurements.txt";
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private static record Measurement(String station, double value) {
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private Measurement(String[] parts) {
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this(parts[0], Double.parseDouble(parts[1]));
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}
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}
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private static record ResultRow(double min, double mean, double max) {
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public String toString() {
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return round(min) + "/" + round(mean) + "/" + round(max);
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}
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private double round(double value) {
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return Math.round(value * 10.0) / 10.0;
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}
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};
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private static class MeasurementAggregator {
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private double min = Double.POSITIVE_INFINITY;
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private double max = Double.NEGATIVE_INFINITY;
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private double sum;
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private long count;
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}
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public static void main(String[] args) throws IOException {
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// Map<String, Double> measurements1 = Files.lines(Paths.get(FILE))
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// .map(l -> l.split(";"))
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// .collect(groupingBy(m -> m[0], averagingDouble(m -> Double.parseDouble(m[1]))));
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//
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// measurements1 = new TreeMap<>(measurements1.entrySet()
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// .stream()
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// .collect(toMap(e -> e.getKey(), e -> Math.round(e.getValue() * 10.0) / 10.0)));
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// System.out.println(measurements1);
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Collector<Measurement, MeasurementAggregator, ResultRow> collector = Collector.of(
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MeasurementAggregator::new,
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(a, m) -> {
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a.min = Math.min(a.min, m.value);
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a.max = Math.max(a.max, m.value);
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a.sum += m.value;
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a.count++;
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},
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(agg1, agg2) -> {
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var res = new MeasurementAggregator();
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res.min = Math.min(agg1.min, agg2.min);
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res.max = Math.max(agg1.max, agg2.max);
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res.sum = agg1.sum + agg2.sum;
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res.count = agg1.count + agg2.count;
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return res;
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},
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agg -> {
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return new ResultRow(agg.min, agg.sum / agg.count, agg.max);
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});
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Map<String, ResultRow> measurements = new TreeMap<>(Files.lines(Paths.get(FILE))
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.map(l -> new Measurement(l.split(";")))
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.collect(groupingBy(m -> m.station(), collector)));
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System.out.println(measurements);
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}
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}
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