Github user ottobackwards commented on a diff in the pull request:
https://github.com/apache/metron/pull/872#discussion_r157332543
--- Diff:
metron-analytics/metron-statistics/src/main/java/org/apache/metron/statistics/informationtheory/InformationTheoryUtil.java
---
@@ -0,0 +1,52 @@
+/*
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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 org.apache.metron.statistics.informationtheory;
+
+import java.util.Map;
+
+public enum InformationTheoryUtil {
+ INSTANCE;
+ private static final double LOG2 = Math.log(2);
+
+ public double entropy(Map<?, Integer> counts, double logOfBase) {
+ double ret = 0.0;
+ int n = 0;
+ if(counts == null || counts.isEmpty()) {
+ return ret;
+ }
+ for(Integer f : counts.values()) {
+ n+=f;
+ }
+
+ for(Integer f : counts.values()) {
+ double p = f.doubleValue()/n;
+ ret -= p * Math.log(p) / logOfBase;
+ }
+ return ret;
+ }
+
--- End diff --
https://github.com/ottobackwards/stream_entropy
---
