80 lines
2.8 KiB
Java
80 lines
2.8 KiB
Java
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/*
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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 java.io.IOException;
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import java.nio.file.Files;
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import java.nio.file.Path;
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import java.util.AbstractMap;
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import java.util.Map;
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import java.util.stream.Collectors;
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public class CalculateAverage_royvanrijn {
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private static final String FILE = "./measurements.txt";
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private record Measurement(double min, double max, double sum, long count) {
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Measurement(double initialMeasurement) {
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this(initialMeasurement, initialMeasurement, initialMeasurement, 1);
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}
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public static Measurement combineWith(Measurement m1, Measurement m2) {
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return new Measurement(
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m1.min < m2.min ? m1.min : m2.min,
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m1.max > m2.max ? m1.max : m2.max,
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m1.sum + m2.sum,
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m1.count + m2.count
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);
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}
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public String toString() {
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return round(min) + "/" + round(sum / count) + "/" + 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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public static void main(String[] args) throws IOException {
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// long before = System.currentTimeMillis();
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Map<String, Measurement> resultMap = Files.lines(Path.of(FILE)).parallel()
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.map(record -> {
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// Map to <String,double>
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int pivot = record.indexOf(";");
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String key = record.substring(0, pivot);
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double measured = Double.parseDouble(record.substring(pivot + 1));
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return new AbstractMap.SimpleEntry<>(key, measured);
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})
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.collect(Collectors.toConcurrentMap(
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// Combine/reduce:
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AbstractMap.SimpleEntry::getKey,
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entry -> new Measurement(entry.getValue()),
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Measurement::combineWith));
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System.out.print("{");
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System.out.print(
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resultMap.entrySet().stream().sorted(Map.Entry.comparingByKey()).map(Object::toString).collect(Collectors.joining(", ")));
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System.out.println("}");
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// System.out.println("Took: " + (System.currentTimeMillis() - before));
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}
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}
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