diff options
Diffstat (limited to 'support/src')
-rw-r--r-- | support/src/test/java/tests/util/SummaryStatistics.java | 82 |
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 index 0000000..4ce0a04 --- /dev/null +++ b/support/src/test/java/tests/util/SummaryStatistics.java @@ -0,0 +1,82 @@ +/* + * 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(); + } +} |