OpenSoure_Repos/TheAlgorithms-C-Plus-Plus
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added test case

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This commit is contained in:
Krishna Vedala 2020-05-30 11:00:08 -04:00
parent b596b7e42d
commit 72f53da5a9
1 changed files with 58 additions and 6 deletions
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64
math/realtime_stats.cpp
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@ -6,13 +6,16 @@
* realtime. For example, devices reading biometrics data. The algorithm is
* simple enough to be easily implemented in an embedded system.
*/
#include <cassert>
#include <cmath>
#include <iostream>
/**
* continuous mean and variance computance using
* first value as an approximation for the mean
**/
* first value as an approximation for the mean.
* If the first number is much far form the mean, the algorithm becomes very
* inaccurate to compute variance and standard deviation.
*/
template <typename T>
class stats_computer1 {
public:
@ -36,7 +39,9 @@ class stats_computer1 {
/** return sample standard deviation computed till last sample */
double std() const { return std::sqrt(this->variance()); }
/** short-hand operator to read new sample from input stream */
/** short-hand operator to read new sample from input stream
* \n e.g.: `std::cin >> stats1;`
*/
friend std::istream &operator>>(std::istream &input,
stats_computer1 &stat) {
T val;
@ -53,8 +58,8 @@ class stats_computer1 {
/**
* continuous mean and variance computance using
* Welford's algorithm
**/
* Welford's algorithm (very accurate)
*/
template <typename T>
class stats_computer2 {
public:
@ -78,7 +83,9 @@ class stats_computer2 {
/** return sample standard deviation computed till last sample */
double std() const { return std::sqrt(this->variance()); }
/** short-hand operator to read new sample from input stream */
/** short-hand operator to read new sample from input stream
* \n e.g.: `std::cin >> stats1;`
*/
friend std::istream &operator>>(std::istream &input,
stats_computer2 &stat) {
T val;
@ -92,8 +99,53 @@ class stats_computer2 {
double mu = 0, var = 0, M = 0;
};
/** Test the algorithm implementation
* \param[in] test_data array of data to test the algorithms
*/
void test_function(const float *test_data, const int number_of_samples) {
float mean = 0.f, variance = 0.f;
stats_computer1<float> stats01;
stats_computer2<float> stats02;
for (int i = 0; i < number_of_samples; i++) {
stats01.new_val(test_data[i]);
stats02.new_val(test_data[i]);
mean += test_data[i];
}
mean /= number_of_samples;
for (int i = 0; i < number_of_samples; i++) {
float temp = test_data[i] - mean;
variance += temp * temp;
}
variance /= number_of_samples;
std::cout << "<<<<<<<< Test Function >>>>>>>>" << std::endl
<< "Expected: Mean: " << mean << "\t Variance: " << variance
<< std::endl;
std::cout << "\tMethod 1:"
<< "\tMean: " << stats01.mean()
<< "\t Variance: " << stats01.variance()
<< "\t Std: " << stats01.std() << std::endl;
std::cout << "\tMethod 2:"
<< "\tMean: " << stats02.mean()
<< "\t Variance: " << stats02.variance()
<< "\t Std: " << stats02.std() << std::endl;
assert(std::abs(stats01.mean() - mean) < 0.01);
assert(std::abs(stats02.mean() - mean) < 0.01);
assert(std::abs(stats02.variance() - variance) < 0.01);
std::cout << "(Tests passed)" << std::endl;
}
/** Main function */
int main(int argc, char **argv) {
const float test_data1[] = {3, 4, 5, -1.4, -3.6, 1.9, 1.};
test_function(test_data1, sizeof(test_data1) / sizeof(test_data1[0]));
std::cout
<< "Enter data. Any non-numeric data will terminate the data input."
<< std::endl;