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
new file mode 100644
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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();
+  }
+}