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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.function.ToDoubleFunction;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class CalculateAverage_kuduwa_keshavram {
private static final String FILE = "./measurements.txt";
private static final Function<String, String> KEY_MAPPER = line -> {
int pivot = line.indexOf(";");
return line.substring(0, pivot);
};
private static final ToDoubleFunction<String> VALUE_MAPPER = line -> {
int pivot = line.indexOf(";");
return toDouble(line.substring(pivot + 1));
};
public static void main(String[] args) throws IOException, InterruptedException {
try (Stream<String> lines = Files.lines(Path.of(FILE))) {
Map<String, DoubleSummaryStatistics> resultMap = lines
.parallel()
.collect(
Collectors.groupingBy(KEY_MAPPER, Collectors.summarizingDouble(VALUE_MAPPER)));
System.out.println(
resultMap.entrySet().stream()
.sorted(Map.Entry.comparingByKey())
.map(
entry -> String.format(
"%s=%.1f/%.1f/%.1f",
entry.getKey(),
entry.getValue().getMin(),
entry.getValue().getAverage(),
entry.getValue().getMax()))
.collect(Collectors.joining(", ", "{", "}")));
}
}
private static final long MAX_VALUE_DIVIDE_10 = Long.MAX_VALUE / 10;
private static double toDouble(String num) {
long value = 0;
int exp = 0;
boolean negative = false;
int decimalPlaces = Integer.MIN_VALUE;
for (byte ch : num.getBytes()) {
if (ch >= '0' && ch <= '9') {
value = value * 10 + (ch - '0');
decimalPlaces++;
}
else if (ch == '-') {
negative = true;
}
else if (ch == '.') {
decimalPlaces = 0;
}
else {
break;
}
}
return asDouble(value, exp, negative, decimalPlaces);
}
private static double asDouble(long value, int exp, boolean negative, int decimalPlaces) {
if (decimalPlaces > 0 && value < Long.MAX_VALUE / 2) {
if (value < Long.MAX_VALUE / (1L << 32)) {
exp -= 32;
value <<= 32;
}
if (value < Long.MAX_VALUE / (1L << 16)) {
exp -= 16;
value <<= 16;
}
if (value < Long.MAX_VALUE / (1L << 8)) {
exp -= 8;
value <<= 8;
}
if (value < Long.MAX_VALUE / (1L << 4)) {
exp -= 4;
value <<= 4;
}
if (value < Long.MAX_VALUE / (1L << 2)) {
exp -= 2;
value <<= 2;
}
if (value < Long.MAX_VALUE / (1L << 1)) {
exp -= 1;
value <<= 1;
}
}
for (; decimalPlaces > 0; decimalPlaces--) {
exp--;
long mod = value % 5;
value /= 5;
int modDiv = 1;
if (value < Long.MAX_VALUE / (1L << 4)) {
exp -= 4;
value <<= 4;
modDiv <<= 4;
}
if (value < Long.MAX_VALUE / (1L << 2)) {
exp -= 2;
value <<= 2;
modDiv <<= 2;
}
if (value < Long.MAX_VALUE / (1L << 1)) {
exp -= 1;
value <<= 1;
modDiv <<= 1;
}
if (decimalPlaces > 1)
value += modDiv * mod / 5;
else
value += (modDiv * mod + 4) / 5;
}
final double d = Math.scalb((double) value, exp);
return negative ? -d : d;
}
}
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