| /* |
| * Copyright (C) 2012 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 com.android.pts.util; |
| |
| /** |
| * Utilities for doing statistics |
| * |
| */ |
| public class Stat { |
| |
| public static class StatResult { |
| public double mAverage; |
| public double mMin; |
| public double mMax; |
| public double mStddev; |
| public StatResult(double average, double min, double max, double stddev) { |
| mAverage = average; |
| mMin = min; |
| mMax = max; |
| mStddev = stddev; |
| } |
| } |
| |
| public static StatResult getStat(double[] data) { |
| double average = data[0]; |
| double min = data[0]; |
| double max = data[0]; |
| double eX2 = data[0] * data[0]; // will become E[X^2] |
| for (int i = 1; i < data.length; i++) { |
| average += data[i]; |
| eX2 += data[i] * data[i]; |
| if (data[i] > max) { |
| max = data[i]; |
| } |
| if (data[i] < min) { |
| min = data[i]; |
| } |
| } |
| average /= data.length; |
| eX2 /= data.length; |
| // stddev = sqrt(E[X^2] - (E[X])^2) |
| double stddev = Math.sqrt(eX2 - average * average); |
| return new StatResult(average, min, max, stddev); |
| } |
| |
| public static double getMin(double[] data) { |
| double min = data[0]; |
| for (int i = 1; i < data.length; i++) { |
| if (data[i] < min) { |
| min = data[i]; |
| } |
| } |
| return min; |
| } |
| |
| public static double getMax(double[] data) { |
| double max = data[0]; |
| for (int i = 1; i < data.length; i++) { |
| if (data[i] > max) { |
| max = data[i]; |
| } |
| } |
| return max; |
| } |
| } |