Prediction of COVID Infection in Texas based on real data

texasCovid.cpp

#include <vector>
#include <iostream>
#include <algorithm>
#include <random>
#include <iomanip>

using namespace std;

const int		NumDays = 45;
const int		PopulationTexas = 30000000;
const double	InfectedPct = 0.046;  // % infected
const int		StartingNumberOfInfected = PopulationTexas * InfectedPct;
const double	FinalInfectedPopulation = 0.15;
const double	DailyInfectionRateIncrease = (FinalInfectedPopulation - InfectedPct) / NumDays;

struct DailyTestResults
{
	double Positive;
	int NumTests;
};

int GetRandomNum()
{
	std::random_device rd;
	std::mt19937 gen(rd());
	std::uniform_int_distribution<> dis(0, PopulationTexas-1);
	return dis(gen);
}

void IncreaseInfectionRate(vector<bool> &Population)
{
	int NewInfected = (double)Population.size() * DailyInfectionRateIncrease;
	for (int i = 0; i < NewInfected; i++)
	{
		// Note: There is a small possibility of marking an infected person infected
		// but shouldn't hurt the final results when dealing with such large numbers
		Population[GetRandomNum()] = true;
	}
}

int main() 
{
	// https://www.khou.com/article/news/health/coronavirus/a-closer-look-at-covid-19-testing-numbers-in-texas/285-2483e965-0baf-4228-8bd9-0ad309b9f1f6
	// Actual tests conducted 5/16 to 7/1
	const vector<DailyTestResults> DailyTests =
	{
		{ 0.0483, 23708 }, { 0.0497, 22004 }, { 0.0447, 24725 }, { 0.047,  26966 }, { 0.0543, 23450 },
		{ 0.0551, 21838 }, { 0.0539, 21868 }, { 0.0487, 22186 }, { 0.0515, 20198 }, { 0.0427, 22218 },
		{ 0.0433, 21756 }, { 0.049,  21871 }, { 0.0456, 23687 }, { 0.0544, 23482 }, { 0.054,  23570 },
		{ 0.0662, 21585 }, { 0.0626, 23620 }, { 0.0603, 24043 }, { 0.0644, 23537 }, { 0.08,	  20021 },
		{ 0.0711, 21469 }, { 0.0666, 23019 }, { 0.0692, 22046 }, { 0.0685, 23966 }, { 0.0705, 23626 },
		{ 0.0722, 23863 }, { 0.0611, 29139 }, { 0.0662, 27778 }, { 0.0671, 28727 }, { 0.0694, 29793 },
		{ 0.075,  28774 }, { 0.0853, 28137 }, { 0.0894, 29011 }, { 0.088,  32885 }, { 0.0951, 33464 },
		{ 0.0964, 35550 }, { 0.1042, 37231 }, { 0.1176, 35943 }, { 0.1173, 39060 }, { 0.1323, 37061 },
		{ 0.1431, 35577 }, { 0.1374, 38597 }, { 0.1402, 38856 }, { 0.1358, 41670 }, { 0.1332, 45209 }
	};

	vector<bool> Population(PopulationTexas, false);

	// Initialize infected population
	int Infected = Population.size() * InfectedPct;
	for (int i = 0; i < Infected; i++) 
	{
		Population[GetRandomNum()] = true;
	}

	int Day = 1;
	int i = 0;

	for (auto& test : DailyTests)
	{
		int Positives = 0;
		// Run daily tests
		for (int i = 0; i < test.NumTests; i++)
		{
			if (Population[GetRandomNum()]) // Infected
				Positives++;
		}
		double PositivityRate = (double)Positives / (double)test.NumTests;
		cout << std::fixed << std::showpoint << std::setprecision(2);
		cout << "Day " << Day++ << " Found " << PositivityRate * 100.0 
			<< "%\tActual: " << test.Positive * 100.0 << "%\n";

		IncreaseInfectionRate(Population);
	}

	int totalSick = 0;
	for (int i = 0; i < Population.size(); i++)
	{
		if (Population[i])
			totalSick++;
	}

	cout << std::fixed << std::showpoint << std::setprecision(4);
	cout << "Found: " << found << "\n";
	cout << "Total Infected is " << totalSick << "\nWhich is a percentage of: " << (double)totalSick / (double)PopulationTexas << "\n";
	cout << "The daily infection increase is about " << DailyInfectionRateIncrease
		<< "%\nWhich means daily infections are about " << PopulationTexas * DailyInfectionRateIncrease << "\n";
	return 0;
}