cs3460-cpp/Hw2/Assignment2.cpp

#include <cstdint>
#include <iomanip>
#include <iostream>
#include <random>
#include <string>

//
// If the default clang follows the the one true brace style is that not
// obviously the better brace style???
//
class DistributionPair
{
  public:
    DistributionPair(std::uint32_t minValue, std::uint32_t maxValue) :
        minValue(minValue), maxValue(maxValue), count(0) {}

    std::uint32_t minValue;
    std::uint32_t maxValue;
    std::uint32_t count;
};

std::vector<DistributionPair>
generateUniformDistribution(std::uint32_t howMany, std::uint32_t min,
                            std::uint32_t max, std::uint8_t numberBins);
std::vector<DistributionPair>
generateNormalDistribution(std::uint32_t howMany, float mean, float stdev,
                           std::uint8_t numberBins);
std::vector<DistributionPair>
generatePoissonDistribution(std::uint32_t howMany, std::uint8_t howOften,
                            std::uint8_t numberBins);
void plotDistribution(std::string title,
                      const std::vector<DistributionPair>& distribution,
                      const std::uint8_t maxPlotLineSize);
std::vector<DistributionPair> createBins(int min, int max, int binCount);

std::random_device randomDevice;
std::default_random_engine randomEngine(randomDevice());

int main()
{
    auto uniform = generateUniformDistribution(100000, 0, 79, 40);
    plotDistribution("--- Uniform ---", uniform, 80);

    auto normal = generateNormalDistribution(100000, 50, 5, 40);
    plotDistribution("--- Normal ---", normal, 80);

    auto poisson = generatePoissonDistribution(100000, 6, 40);
    plotDistribution("--- Poisson ---", poisson, 80);

    return 0;
}

std::vector<DistributionPair>
generateUniformDistribution(std::uint32_t howMany, std::uint32_t min,
                            std::uint32_t max, std::uint8_t numberBins)
{
    std::uniform_int_distribution<int> distribution(min, max);
    auto bins = createBins(min, max, numberBins);
    for (int i = 0; i < static_cast<int>(howMany); i++)
    {
        int number = distribution(randomEngine);

        for (int j = 0; j <= numberBins; j++)
        {
            if (static_cast<int>(bins[j].maxValue) >= number && static_cast<int>(bins[j].minValue) <= number)
                bins[j].count++;
        }
    }
    return bins;
}

std::vector<DistributionPair>
generateNormalDistribution(std::uint32_t howMany, float mean, float stdev,
                           std::uint8_t numberBins)
{
    int min = static_cast<int>(mean - (4 * stdev));
    int max = static_cast<int>(mean + (4 * stdev) - 1);
    std::normal_distribution<double> distribution(mean, stdev);
    auto bins = createBins(min, max, numberBins);

    for (int i = 0; i < static_cast<int>(howMany); i++)
    {
        double number = distribution(randomEngine);
        int position =
            static_cast<int>(number - min / ((max - min) / float(numberBins)));
        if (position > numberBins - 1)
            bins[numberBins - 1].count++;
        else if (position < 0)
            bins[0].count++;
        else
            bins[position].count++;
    }
    return bins;
}
std::vector<DistributionPair>
generatePoissonDistribution(std::uint32_t howMany, std::uint8_t howOften,
                            std::uint8_t numberBins)
{
    std::poisson_distribution<int> distribution(howOften);
    int min = 0;
    int max = numberBins - 1;
    auto bins = createBins(min, max, numberBins);
    for (int i = 0; i < static_cast<int>(howMany); i++)
    {
        int number = distribution(randomEngine);
        if (number > numberBins - 1)
            bins[numberBins - 1].count++;
        else if (number < 0)
            bins[0].count++;
        else
            bins[number].count++;
    }
    return bins;
}

std::vector<DistributionPair> createBins(int min, int max, int binCount)
{
    std::vector<DistributionPair> myVector;
    int difference = static_cast<int>(float(max - min + 1) / binCount);
    for (int i = 0; i < binCount; i++)
    {
        DistributionPair dpair((min + i) * difference,
                               (min + i) * difference + difference - 1);
        myVector.push_back(dpair);
    }
    return myVector;
}

void plotDistribution(std::string title,
                      const std::vector<DistributionPair>& distribution,
                      const std::uint8_t maxPlotLineSize)
{
    std::cout << title << std::endl;
    auto max = 0;
    for (auto currentBin : distribution)
    {
        if (static_cast<int>(currentBin.count) > static_cast<int>(max))
            max = currentBin.count;
    }
    for (auto currentBin : distribution)
    {
        int starCount =
            static_cast<int>(currentBin.count / float(max) * maxPlotLineSize);
        std::string info = "[ " + std::to_string(currentBin.minValue) + ", " + std::to_string(currentBin.maxValue) + " ] : ";
        std::string starString;
        for (int i = 0; i < starCount; i++)
            starString += "*";
        std::cout << std::setw(15) << info << starString;
        std::cout << std::endl;
    }
}