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-rw-r--r--support/src/test/java/tests/util/SummaryStatistics.java82
1 files changed, 82 insertions, 0 deletions
diff --git a/support/src/test/java/tests/util/SummaryStatistics.java b/support/src/test/java/tests/util/SummaryStatistics.java
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+++ b/support/src/test/java/tests/util/SummaryStatistics.java
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+/*
+ * Copyright 2015 The Android Open Source Project
+ *
+ * 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 tests.util;
+
+public class SummaryStatistics {
+ /** The number of values seen. */
+ private int numValues;
+
+ /** Sum of the values. */
+ private double sum;
+
+ /** Sum of the squares of the values added. */
+ private double squaresSum;
+
+ /** The previously added value. */
+ private double lastValue;
+
+ public SummaryStatistics() {
+ }
+
+ private double square(double value) {
+ return value * value;
+ }
+
+ /** Add a new value to the values seen. */
+ public void add(double value) {
+ sum += value - lastValue;
+ squaresSum += square(value) - square(lastValue);
+ numValues++;
+ lastValue = value;
+ }
+
+ /** Mean of the values seen. */
+ public double mean() {
+ return sum / numValues;
+ }
+
+ /** Variance of the values seen. */
+ public double var() {
+ return (squaresSum / numValues) - square(mean());
+ }
+
+ /** Standard deviation of the values seen. */
+ public double stddev() {
+ return Math.sqrt(var());
+ }
+
+ /** Coefficient of variation of the values seen. */
+ public double coeffVar() {
+ return stddev() / mean();
+ }
+
+ public String toString() {
+ StringBuilder sb = new StringBuilder("SummaryStatistics{");
+ sb.append("n=");
+ sb.append(numValues);
+ sb.append(",mean=");
+ sb.append(mean());
+ sb.append(",var=");
+ sb.append(var());
+ sb.append(",stddev=");
+ sb.append(stddev());
+ sb.append(",coeffVar=");
+ sb.append(coeffVar());
+ sb.append('}');
+ return sb.toString();
+ }
+}