OpenSoure_Repos/TheAlgorithms-C-Plus-Plus
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added comments to the code

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This commit is contained in:
Krishna Vedala 2020-05-30 09:35:27 -04:00
parent 6da2b9645a
commit b596b7e42d
1 changed files with 89 additions and 60 deletions
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43
math/realtime_stats.cpp
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@ -1,3 +1,11 @@
/**
* \file
* \brief Compute statistics for data entered in rreal-time
*
* This algorithm is really beneficial to compute statistics on data read in
* realtime. For example, devices reading biometrics data. The algorithm is
* simple enough to be easily implemented in an embedded system.
*/
#include <cmath> #include <cmath>
#include <iostream> #include <iostream>
@ -8,6 +16,9 @@
template <typename T> template <typename T>
class stats_computer1 { class stats_computer1 {
public: public:
/** Constructor
* \param[in] x new data sample
*/
void new_val(T x) { void new_val(T x) {
if (n == 0) K = x; if (n == 0) K = x;
n++; n++;
@ -16,13 +27,18 @@ class stats_computer1 {
Ex2 += tmp * tmp; Ex2 += tmp * tmp;
} }
/** return sample mean computed till last sample */
double mean() const { return K + Ex / n; } double mean() const { return K + Ex / n; }
/** return data variance computed till last sample */
double variance() const { return (Ex2 - (Ex * Ex) / n) / (n - 1); } double variance() const { return (Ex2 - (Ex * Ex) / n) / (n - 1); }
/** return sample standard deviation computed till last sample */
double std() const { return std::sqrt(this->variance()); } double std() const { return std::sqrt(this->variance()); }
friend std::istream &operator>>(std::istream &input, stats_computer1 &stat) { /** short-hand operator to read new sample from input stream */
friend std::istream &operator>>(std::istream &input,
stats_computer1 &stat) {
T val; T val;
input >> val; input >> val;
stat.new_val(val); stat.new_val(val);
@ -42,6 +58,9 @@ class stats_computer1 {
template <typename T> template <typename T>
class stats_computer2 { class stats_computer2 {
public: public:
/** Constructor
* \param[in] x new data sample
*/
void new_val(T x) { void new_val(T x) {
n++; n++;
double delta = x - mu; double delta = x - mu;
@ -50,13 +69,18 @@ class stats_computer2 {
M += delta * delta2; M += delta * delta2;
} }
/** return sample mean computed till last sample */
double mean() const { return mu; } double mean() const { return mu; }
/** return data variance computed till last sample */
double variance() const { return M / n; } double variance() const { return M / n; }
/** return sample standard deviation computed till last sample */
double std() const { return std::sqrt(this->variance()); } double std() const { return std::sqrt(this->variance()); }
friend std::istream &operator>>(std::istream &input, stats_computer2 &stat) { /** short-hand operator to read new sample from input stream */
friend std::istream &operator>>(std::istream &input,
stats_computer2 &stat) {
T val; T val;
input >> val; input >> val;
stat.new_val(val); stat.new_val(val);
@ -68,22 +92,27 @@ class stats_computer2 {
double mu = 0, var = 0, M = 0; double mu = 0, var = 0, M = 0;
}; };
/** Main function */
int main(int argc, char **argv) { int main(int argc, char **argv) {
std::cout << "Enter data. Any non-numeric data will terminate the data input." std::cout
<< "Enter data. Any non-numeric data will terminate the data input."
<< std::endl; << std::endl;
stats_computer1<double> stats1; stats_computer1<float> stats1;
stats_computer2<double> stats2; stats_computer2<float> stats2;
while (1) { while (1) {
double val; double val;
std::cout << "Enter number: "; std::cout << "Enter number: ";
std::cin >> val; std::cin >> val;
if (std::cin.fail()) // check for failure to read input. Happens for
// check for failure to read input. Happens for
// non-numeric data // non-numeric data
break; if (std::cin.fail()) break;
stats1.new_val(val); stats1.new_val(val);
stats2.new_val(val); stats2.new_val(val);
std::cout << "\tMethod 1:" std::cout << "\tMethod 1:"
<< "\tMean: " << stats1.mean() << "\tMean: " << stats1.mean()
<< "\t Variance: " << stats1.variance() << "\t Variance: " << stats1.variance()