my 1brc entry (#367)

calculate_average_ivanklaric.sh

@@ -0,0 +1,19 @@
+#!/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=""
+java $JAVA_OPTS --class-path target/average-1.0.0-SNAPSHOT.jar dev.morling.onebrc.CalculateAverage_ivanklaric

src/main/java/dev/morling/onebrc/CalculateAverage_ivanklaric.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.ConcurrentSkipListMap;
+import java.util.concurrent.ConcurrentMap;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.stream.Stream;
+
+public class CalculateAverage_ivanklaric {
+    private static final String FILE = "measurements.txt";
+
+    record CityTemps (double min, double max, double sum, long count) {
+        public String toString() {
+            return round(min) + "/" + round(sum / count) + "/" + round(max);
+        }
+
+        private double round(double num) {
+            return Math.round(num * 10.0) / 10.0;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        Stream<String> lines = Files.lines(Paths.get(FILE));
+        ConcurrentMap<String, CityTemps> cityStats = new ConcurrentSkipListMap<>();
+
+        lines.parallel().forEach(line -> {
+            int splitterLoc = line.indexOf(';');
+            double temp = Double.parseDouble(line.substring(splitterLoc + 1, line.length()));
+
+            cityStats.merge(line.substring(0, splitterLoc), new CityTemps(temp, temp, temp, 1),
+                    (oldValue, defaultValue) -> {
+                        return new CityTemps(Math.min(oldValue.min, temp), Math.max(oldValue.max, temp), oldValue.sum + temp, oldValue.count + 1);
+                    });
+        });
+        System.out.println(cityStats);
+    }
+}