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Diffstat (limited to '')
-rw-r--r-- | third_party/libwebrtc/rtc_base/numerics/running_statistics_unittest.cc | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/numerics/running_statistics_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/running_statistics_unittest.cc new file mode 100644 index 0000000000..d593f3fc5a --- /dev/null +++ b/third_party/libwebrtc/rtc_base/numerics/running_statistics_unittest.cc @@ -0,0 +1,196 @@ +/* + * Copyright (c) 2016 The WebRTC project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ + +#include "rtc_base/numerics/running_statistics.h" + +#include <math.h> + +#include <random> +#include <vector> + +#include "absl/algorithm/container.h" +#include "test/gtest.h" + +// Tests were copied from samples_stats_counter_unittest.cc. + +namespace webrtc { +namespace webrtc_impl { +namespace { + +RunningStatistics<double> CreateStatsFilledWithIntsFrom1ToN(int n) { + std::vector<double> data; + for (int i = 1; i <= n; i++) { + data.push_back(i); + } + absl::c_shuffle(data, std::mt19937(std::random_device()())); + + RunningStatistics<double> stats; + for (double v : data) { + stats.AddSample(v); + } + return stats; +} + +// Add n samples drawn from uniform distribution in [a;b]. +RunningStatistics<double> CreateStatsFromUniformDistribution(int n, + double a, + double b) { + std::mt19937 gen{std::random_device()()}; + std::uniform_real_distribution<> dis(a, b); + + RunningStatistics<double> stats; + for (int i = 1; i <= n; i++) { + stats.AddSample(dis(gen)); + } + return stats; +} + +class RunningStatisticsTest : public ::testing::TestWithParam<int> {}; + +constexpr int SIZE_FOR_MERGE = 5; + +TEST(RunningStatistics, FullSimpleTest) { + auto stats = CreateStatsFilledWithIntsFrom1ToN(100); + + EXPECT_DOUBLE_EQ(*stats.GetMin(), 1.0); + EXPECT_DOUBLE_EQ(*stats.GetMax(), 100.0); + // EXPECT_DOUBLE_EQ is too strict (max 4 ULP) for this one. + ASSERT_NEAR(*stats.GetMean(), 50.5, 1e-10); +} + +TEST(RunningStatistics, VarianceAndDeviation) { + RunningStatistics<int> stats; + stats.AddSample(2); + stats.AddSample(2); + stats.AddSample(-1); + stats.AddSample(5); + + EXPECT_DOUBLE_EQ(*stats.GetMean(), 2.0); + EXPECT_DOUBLE_EQ(*stats.GetVariance(), 4.5); + EXPECT_DOUBLE_EQ(*stats.GetStandardDeviation(), sqrt(4.5)); +} + +TEST(RunningStatistics, RemoveSample) { + // We check that adding then removing sample is no-op, + // or so (due to loss of precision). + RunningStatistics<int> stats; + stats.AddSample(2); + stats.AddSample(2); + stats.AddSample(-1); + stats.AddSample(5); + + constexpr int iterations = 1e5; + for (int i = 0; i < iterations; ++i) { + stats.AddSample(i); + stats.RemoveSample(i); + + EXPECT_NEAR(*stats.GetMean(), 2.0, 1e-8); + EXPECT_NEAR(*stats.GetVariance(), 4.5, 1e-3); + EXPECT_NEAR(*stats.GetStandardDeviation(), sqrt(4.5), 1e-4); + } +} + +TEST(RunningStatistics, RemoveSamplesSequence) { + // We check that adding then removing a sequence of samples is no-op, + // or so (due to loss of precision). + RunningStatistics<int> stats; + stats.AddSample(2); + stats.AddSample(2); + stats.AddSample(-1); + stats.AddSample(5); + + constexpr int iterations = 1e4; + for (int i = 0; i < iterations; ++i) { + stats.AddSample(i); + } + for (int i = 0; i < iterations; ++i) { + stats.RemoveSample(i); + } + + EXPECT_NEAR(*stats.GetMean(), 2.0, 1e-7); + EXPECT_NEAR(*stats.GetVariance(), 4.5, 1e-3); + EXPECT_NEAR(*stats.GetStandardDeviation(), sqrt(4.5), 1e-4); +} + +TEST(RunningStatistics, VarianceFromUniformDistribution) { + // Check variance converge to 1/12 for [0;1) uniform distribution. + // Acts as a sanity check for NumericStabilityForVariance test. + auto stats = CreateStatsFromUniformDistribution(1e6, 0, 1); + + EXPECT_NEAR(*stats.GetVariance(), 1. / 12, 1e-3); +} + +TEST(RunningStatistics, NumericStabilityForVariance) { + // Same test as VarianceFromUniformDistribution, + // except the range is shifted to [1e9;1e9+1). + // Variance should also converge to 1/12. + // NB: Although we lose precision for the samples themselves, the fractional + // part still enjoys 22 bits of mantissa and errors should even out, + // so that couldn't explain a mismatch. + auto stats = CreateStatsFromUniformDistribution(1e6, 1e9, 1e9 + 1); + + EXPECT_NEAR(*stats.GetVariance(), 1. / 12, 1e-3); +} + +TEST(RunningStatistics, MinRemainsUnchangedAfterRemove) { + // We don't want to recompute min (that's RollingAccumulator's role), + // check we get the overall min. + RunningStatistics<int> stats; + stats.AddSample(1); + stats.AddSample(2); + stats.RemoveSample(1); + EXPECT_EQ(stats.GetMin(), 1); +} + +TEST(RunningStatistics, MaxRemainsUnchangedAfterRemove) { + // We don't want to recompute max (that's RollingAccumulator's role), + // check we get the overall max. + RunningStatistics<int> stats; + stats.AddSample(1); + stats.AddSample(2); + stats.RemoveSample(2); + EXPECT_EQ(stats.GetMax(), 2); +} + +TEST_P(RunningStatisticsTest, MergeStatistics) { + int data[SIZE_FOR_MERGE] = {2, 2, -1, 5, 10}; + // Split the data in different partitions. + // We have 6 distinct tests: + // * Empty merged with full sequence. + // * 1 sample merged with 4 last. + // * 2 samples merged with 3 last. + // [...] + // * Full merged with empty sequence. + // All must lead to the same result. + // I miss QuickCheck so much. + RunningStatistics<int> stats0, stats1; + for (int i = 0; i < GetParam(); ++i) { + stats0.AddSample(data[i]); + } + for (int i = GetParam(); i < SIZE_FOR_MERGE; ++i) { + stats1.AddSample(data[i]); + } + stats0.MergeStatistics(stats1); + + EXPECT_EQ(stats0.Size(), SIZE_FOR_MERGE); + EXPECT_DOUBLE_EQ(*stats0.GetMin(), -1); + EXPECT_DOUBLE_EQ(*stats0.GetMax(), 10); + EXPECT_DOUBLE_EQ(*stats0.GetMean(), 3.6); + EXPECT_DOUBLE_EQ(*stats0.GetVariance(), 13.84); + EXPECT_DOUBLE_EQ(*stats0.GetStandardDeviation(), sqrt(13.84)); +} + +INSTANTIATE_TEST_SUITE_P(RunningStatisticsTests, + RunningStatisticsTest, + ::testing::Range(0, SIZE_FOR_MERGE + 1)); + +} // namespace +} // namespace webrtc_impl +} // namespace webrtc |