From 893b56179c50b2d3bf76050554d7e2f2e4145809 Mon Sep 17 00:00:00 2001
From: SoftwareObservatorium <kessel@informatik.uni-mannheim.de>
Date: Tue, 4 Apr 2023 16:07:42 +0200
Subject: [PATCH] Hadoop Vertiefung

---
 .../src/main/java/de/hsma/bdea/JavaMVM.java   | 28 +++++++++++++++++++
 .../src/main/java/de/hsma/bdea/MVM2.java      |  4 +--
 2 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/JavaMVM.java

diff --git a/HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/JavaMVM.java b/HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/JavaMVM.java
new file mode 100644
index 0000000..72fe925
--- /dev/null
+++ b/HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/JavaMVM.java
@@ -0,0 +1,28 @@
+package de.hsma.bdea;
+
+import java.util.Arrays;
+
+public class JavaMVM {
+
+    public static void main(String[] args) {
+        double[] vector = {1, 2, 3};
+
+        double[][] matrix = {
+                {3, 2, 1},
+                {5, 4, 3},
+                {7, 8, 9}
+        };
+
+        double[] result = new double[vector.length];
+
+        for (int i = 0; i < matrix.length; i++) {
+            double sum = 0;
+            for (int j = 0; j < matrix.length; j++) {
+                sum += matrix[i][j] * vector[j];
+            }
+            result[i] = sum;
+        }
+
+        System.out.println(Arrays.toString(result));
+    }
+}
diff --git a/HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/MVM2.java b/HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/MVM2.java
index 67d6464..6cadede 100644
--- a/HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/MVM2.java
+++ b/HadoopSS23/Hadoop/src/main/java/de/hsma/bdea/MVM2.java
@@ -33,7 +33,7 @@ public class MVM2 {
 
 		Configuration conf = new Configuration();
 //		conf.set("length", "3");
-		length = 3; // ggf. mit einem vorherigen Job ermitteln
+		length = 3; // Anzahl Spalten in Matrix (== Zeilen Vector) (ggf. mit einem vorherigen Job ermitteln)
 		Job job = Job.getInstance(conf, "mvm1");
 
 		job.setJarByClass(MVM2.class);
@@ -60,7 +60,7 @@ public class MVM2 {
 		job.setMapperClass(Mapper.class);
 		job.setReducerClass(MVMReducer.class);
 		job.setNumReduceTasks(2);
-		job.setPartitionerClass(VectorPartitioner.class);
+		job.setPartitionerClass(VectorPartitioner.class); // zur Sortierung nach Vektor Koordinate (optional)
 		
 		job.setOutputKeyClass(Text.class);
 		job.setOutputValueClass(IntWritable.class);