Implements CalculateAverage_santanu.java

Execution time: 1 minute and 27.863 seconds
System specs: Apple M1, 8 cores, 16GB RAM

Co-authored-by: santanu barua <santanu@host109.private.net>

calculate_average_santanu.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+#
+#  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.
+#
+
+
+JAVA_OPTS=""
+time java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_santanu

src/main/java/dev/morling/onebrc/CalculateAverage_santanu.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.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) {
+    }
+}