Source

`stdlib/tests/statistics_test.cpp`

2// Original work; see ACKNOWLEDGMENTS.md for the open-source ideas we build upon.

3#include "statistics.hpp"

5#include <cmath>

6#include <vector>

8#include <gtest/gtest.h>

10namespace stats = cheatah::statistics;

12TEST(CheatahStatistics, SumCountMean) {

13 const std::vector<double> d{2.0, 4.0, 4.0, 4.0, 5.0, 5.0, 7.0, 9.0};

14 EXPECT_DOUBLE_EQ(stats::sum(d), 40.0);

15 EXPECT_EQ(stats::count(d), 8u);

16 EXPECT_DOUBLE_EQ(stats::mean(d), 5.0);

17}

19TEST(CheatahStatistics, MedianOddAndEven) {

20 EXPECT_DOUBLE_EQ(stats::median(std::vector<double>{3.0, 1.0, 2.0}), 2.0); // odd → middle

21 EXPECT_DOUBLE_EQ(stats::median(std::vector<double>{1.0, 2.0, 3.0, 4.0}), 2.5); // even → mean of two

22}

24TEST(CheatahStatistics, PopulationVarianceAndStdev) {

25 const std::vector<double> d{2.0, 4.0, 4.0, 4.0, 5.0, 5.0, 7.0, 9.0};

26 EXPECT_DOUBLE_EQ(stats::pvariance(d), 4.0); // divide by N

27 EXPECT_DOUBLE_EQ(stats::pstdev(d), 2.0);

28}

30TEST(CheatahStatistics, SampleVarianceAndStdev) {

31 const std::vector<double> d{1.0, 2.0, 3.0, 4.0, 5.0}; // mean 3, Σ(x-μ)² = 10

32 EXPECT_DOUBLE_EQ(stats::variance(d), 2.5); // divide by N-1 → 10/4

33 EXPECT_DOUBLE_EQ(stats::stdev(d), std::sqrt(2.5));

34}