HostPopulation.java

/* A population of host individuals */

import java.util.*;
import java.io.*;
import java.util.regex.*;

public class HostPopulation {

	// fields
	private int deme;
	private String name;	
	private int cases;	
	private List<Host> susceptibles = new ArrayList<>();
	private List<Host> infecteds = new ArrayList<>();
	private List<Host> recovereds = new ArrayList<>();		// this is the transcendental class, immune to all forms of virus
	private double diversity;
	private double tmrca;
	private double netau;	
	private double serialInterval;
	private double antigenicDiversity;
	
	private int newContacts;
	private int newRecoveries;
		
	// construct population, using Virus v as initial infection
	public HostPopulation(int d) {
	
		// basic parameters
		deme = d;
		name = Parameters.demeNames[deme];
		int initialR = 0;
		if (Parameters.transcendental) {
			initialR = (int) ((double) Parameters.initialNs[deme] * Parameters.initialPrT);
		}
	
		// fill population with susceptibles
		int initialS = Parameters.initialNs[deme] - initialR;
		if (deme == Parameters.initialDeme - 1) {
			initialS -= Parameters.initialI;
		}
		for (int i = 0; i < initialS; i++) {
			Host h = new Host();			
			susceptibles.add(h);
		}
		
		// fill population with recovereds
		for (int i = 0; i < initialR; i++) {
			Host h = new Host();			
			recovereds.add(h);
		}		
		
		if (deme == Parameters.initialDeme - 1) {
		
			// infect some individuals
			for (int i = 0; i < Parameters.initialI; i++) {
				Virus v = new Virus(Parameters.urVirus, deme);
				Host h = new Host(v);
				infecteds.add(h);
			}	
		
		}
		
	}
	
	// construct checkpointed host population and infecting viruses
	public HostPopulation(int d, boolean checkpoint) {
	
		if (checkpoint) {
		
			deme = d;
			name = Parameters.demeNames[deme];
		
			try {
    			BufferedReader in = new BufferedReader(new FileReader("out.hosts"));
    			String line;
    			while ((line = in.readLine()) != null) {
    				Pattern regex = Pattern.compile(":");
    				String[] items = regex.split(line);
    				int thisDeme = Integer.parseInt(items[0]);
    				String sVirus = items[1];
    				String sHist = items[2];
        			if (thisDeme == deme) {
        				Host h = new Host(deme, sVirus, sHist);
        				if (sVirus.equals("n")) {
        					susceptibles.add(h);	
        				}
        				else {
        					infecteds.add(h);
        				}
        			}
    			}
    		in.close();
			} 
			catch (IOException ex) {
				System.out.println("Could not read in out.hosts"); 
				System.exit(0);
			}
		
		}
	
	}
	
	// accessors
	public int getN() {
		return susceptibles.size() + infecteds.size() + recovereds.size();
	}
	public int getS() {
		return susceptibles.size();
	}
	public int getI() {
		return infecteds.size();
	}
	public int getR() {
		return recovereds.size();
	}	
	public double getPrS() {
		return (double) getS() / (double) getN();
	}
	public double getPrI() {
		return (double) getI() / (double) getN();
	}
	public double getPrR() {
		return (double) getR() / (double) getN();
	}	
	public int getRandomN() {
		return Random.nextInt(0,getN()-1);
	}
	public int getRandomS() {
		return Random.nextInt(0,getS()-1);
	}
	public int getRandomI() {
		return Random.nextInt(0,getI()-1);
	}
	public int getRandomR() {
		return Random.nextInt(0,getR()-1);
	}
	
	public Host getRandomHost() {
		// figure out whether to pull from S, I or R
		Host h = null;
		double n = Random.nextDouble(0.0,1.0);
		if (n < getPrS()) {
			h = getRandomHostS();
		}
		else if (n > getPrS() && n < getPrS() + getPrI()) {
			h = getRandomHostI();
		}
		else if (n > getPrS() + getPrI()) {
			h = getRandomHostR();
		}
		return h;
	}
	
	public Host getRandomHostS() {
		int index = Random.nextInt(0,getS()-1);
		return susceptibles.get(index);
	}
	public Host getRandomHostI() {
		Host h = null;
		if (getI() > 0) {
			int index = Random.nextInt(0,getI()-1);
			h = infecteds.get(index);
		}
		return h;
	}
	public Host getRandomHostR() {
		Host h = null;
		if (getR() > 0) {	
			int index = Random.nextInt(0,getR()-1);
			h = recovereds.get(index);
		}
		return h;
	}	
	
	public Virus getRandomInfection() {
		Virus v = null;
		Host h = getRandomHostI();
		if (h != null) {
			v = h.getInfection();
		}
		return v;
	}	
	
	public void resetCases() {
		cases = 0;
	}
	public int getCases() {
		return cases;
	}	

	public double getDiversity() {
		return diversity;
	}		
	
	public double getNetau() {
		return netau;
	}	
	
	public double getTmrca() {
		return tmrca;
	}	
	
	public double getSerialInterval() {
		return serialInterval;	
	}		
	
	public double getAntigenicDiversity() {
		return antigenicDiversity;
	}			
	
	public void removeSusceptible(int i) {
		int lastIndex = getS() - 1;
		Host lastHost = susceptibles.get(lastIndex);
		susceptibles.set(i,lastHost);
		susceptibles.remove(lastIndex);
	}	
	public void removeInfected(int i) {
		int lastIndex = getI() - 1;
		Host lastHost = infecteds.get(lastIndex);
		infecteds.set(i,lastHost);
		infecteds.remove(lastIndex);
	}
	public void removeRecovered(int i) {
		int lastIndex = getR() - 1;
		Host lastHost = recovereds.get(lastIndex);
		recovereds.set(i,lastHost);
		recovereds.remove(lastIndex);
	}	
	
	public void stepForward() {
	
	//	resetCases();
		if (Parameters.swapDemography) {
			swap();
		} else {
			grow();
			decline();
		}
		recordContacts();
		recordRecoveries();
		distributeContacts();
		distributeRecoveries();				
		if (Parameters.transcendental) { 
			loseImmunity(); 
		}
		if (Parameters.waning) {
			waneImmunity();
		}
		mutate();
		sample();

	
	}
	
	// draw a Poisson distributed number of births and add these hosts to the end of the population list
	public void grow() {
		double totalBirthRate = getN() * Parameters.birthRate * Parameters.deltaT;
		int births = Random.nextPoisson(totalBirthRate);
		for (int i = 0; i < births; i++) {
			Host h = new Host();
			susceptibles.add(h);
		}
	}
	
	// draw a Poisson distributed number of deaths and remove random hosts from the population list
	public void decline() {
		// deaths in susceptible class
		double totalDeathRate = getS() * Parameters.deathRate * Parameters.deltaT;
		int deaths = Random.nextPoisson(totalDeathRate);
		for (int i = 0; i < deaths; i++) {
			if (getS()>0) {
				int index = getRandomS();
				removeSusceptible(index);
			}
		}		
		// deaths in infectious class		
		totalDeathRate = getI() * Parameters.deathRate * Parameters.deltaT;
		deaths = Random.nextPoisson(totalDeathRate);
		for (int i = 0; i < deaths; i++) {
			if (getI()>0) {
				int index = getRandomI();
				removeInfected(index);
			}
		}
		// deaths in recovered class		
		totalDeathRate = getR() * Parameters.deathRate * Parameters.deltaT;
		deaths = Random.nextPoisson(totalDeathRate);
		for (int i = 0; i < deaths; i++) {
			if (getR()>0) {
				int index = getRandomR();
				removeRecovered(index);
			}
		}				
	}
	
	// draw a Poisson distributed number of births and reset these individuals
	public void swap() {
		// draw random individuals from susceptible class
		double totalBirthRate = getS() * Parameters.birthRate * Parameters.deltaT;
		int births = Random.nextPoisson(totalBirthRate);
		for (int i = 0; i < births; i++) {
			if (getS()>0) {
				int index = getRandomS();
				Host h = susceptibles.get(index);
				h.reset();
			}
		}		
		// draw random individuals from infected class
		totalBirthRate = getI() * Parameters.birthRate * Parameters.deltaT;
		births = Random.nextPoisson(totalBirthRate);
		for (int i = 0; i < births; i++) {
			if (getI()>0) {
				int index = getRandomI();
				Host h = infecteds.get(index);
				h.reset();
				removeInfected(index);
				susceptibles.add(h);
			}
		}	
		// draw random individuals from recovered class
		totalBirthRate = getR() * Parameters.birthRate * Parameters.deltaT;
		births = Random.nextPoisson(totalBirthRate);
		for (int i = 0; i < births; i++) {
			if (getR()>0) {
				int index = getRandomR();
				Host h = recovereds.get(index);
				h.reset();
				removeRecovered(index);
				susceptibles.add(h);
			}
		}			
	}
	
	// draw a Poisson distributed number of contacts
	public void recordContacts() {
		// each infected makes I->S contacts on a per-day rate of beta * S/N
		double totalContactRate = getI() * getPrS() * Parameters.beta * Parameters.getSeasonality(deme) * Parameters.deltaT;
		newContacts = Random.nextPoisson(totalContactRate);			
	}

	// move from S->I following number of new contacts
	public void distributeContacts() {
		
		for (int i = 0; i < newContacts; i++) {
			if (getS()>0 && getI()>0) {
		
				// get indices and objects
				int index = getRandomI();
				int sndex = getRandomS();			
				Host iH = infecteds.get(index);			
				Host sH = susceptibles.get(sndex);						
				Virus v = iH.getInfection();
					
				// attempt infection
				Phenotype p = v.getPhenotype();		
				Phenotype[] history = sH.getHistory();
				double chanceOfSuccess = p.riskOfInfection(history);
				if (Random.nextBoolean(chanceOfSuccess)) {
					sH.infect(v,deme);
					removeSusceptible(sndex);
					infecteds.add(sH);
					cases++;
				}
				// If there is not fitness, assign now.
				if (v.getFitness() == 0.0) {
					double risk = getAverageRisk(p);
					v.setFitness(risk);
				}
			
			}
		}		
		
	}
	
	// draw a Poisson distributed number of contacts and move from S->I based upon this
	// this deme is susceptibles and other deme is infecteds
	public void betweenDemeContact(HostPopulation hp) {

		// each infected makes I->S contacts on a per-day rate of beta * S/N
		double totalContactRate = hp.getI() * getPrS() * Parameters.beta * Parameters.betweenDemePro * Parameters.getSeasonality(deme) * Parameters.deltaT;
		int contacts = Random.nextPoisson(totalContactRate);
		for (int i = 0; i < contacts; i++) {
			if (getS()>0 && hp.getI()>0) {
		
				// get indices and objects
				Host iH = hp.getRandomHostI();
				int sndex = getRandomS();
				Host sH = susceptibles.get(sndex);
				Virus v = iH.getInfection();
				
				// attempt infection
				Phenotype p = v.getPhenotype();
				Phenotype[] history = sH.getHistory();
				double chanceOfSuccess = p.riskOfInfection(history);
				if (Random.nextBoolean(chanceOfSuccess)) {
					sH.infect(v,deme);
					removeSusceptible(sndex);
					infecteds.add(sH);
					cases++;
				}
			
			}
		}		
		
	}	
	
	// draw a Poisson distributed number of recoveries
	public void recordRecoveries() {	
		// each infected recovers at a per-day rate of nu
		double totalRecoveryRate = getI() * Parameters.nu * Parameters.deltaT;
		newRecoveries = Random.nextPoisson(totalRecoveryRate);	
	}
	
	// move from I->S following number of recoveries
	public void distributeRecoveries() {

		for (int i = 0; i < newRecoveries; i++) {
			if (getI()>0) {
				int index = getRandomI();
				Host h = infecteds.get(index);
				h.clearInfection();
				removeInfected(index);
				if (Parameters.transcendental) {
					recovereds.add(h);
				} else {
					susceptibles.add(h);
				}

			}
		}			
	}
	
	// draw a Poisson distributed number of R->S 
	public void loseImmunity() {
		// each recovered regains immunity at a per-day rate
		double totalReturnRate = getR() * Parameters.immunityLoss * Parameters.deltaT;
		int returns = Random.nextPoisson(totalReturnRate);
		for (int i = 0; i < returns; i++) {
			if (getR()>0) {
				int index = getRandomR();
				Host h = recovereds.get(index);
				removeRecovered(index);
				susceptibles.add(h);
			}
		}			
	}	

	// draw a Poisson distributed number of waning events
	public void waneImmunity() {
		// each host wanes at a per-day rate of waningRate
		double totalWaningRate = getN() * Parameters.waningRate * Parameters.deltaT;		
		int wanings = Random.nextPoisson(totalWaningRate);
		for (int i = 0; i < wanings; i++) {
			Host h = getRandomHost();
			h.waneImmunity();
		}	
	}	
	
	// draw a Poisson distributed number of mutations and mutate based upon this
	// mutation should not impact other Virus's Phenotypes through reference
	public void mutate() {
		// each infected mutates at a per-day rate of mu
		double totalMutationRate = getI() * Parameters.muPhenotype * Parameters.deltaT;
		int mutations = Random.nextPoisson(totalMutationRate);
		for (int i = 0; i < mutations; i++) {
			if (getI()>0) {
				int index = getRandomI();
				Host h = infecteds.get(index);
				Virus v = h.mutate();
				Phenotype p = v.getPhenotype();
				double risk = getAverageRisk(p);
				v.setFitness(risk);
			}
		}			
	}	
	
	// Get average infection risk of a phenotype amongst a given sample size
	private double getAverageRisk(Phenotype p) {
		double sampleSize = (double) Parameters.fitnessSampleSize;
		double averageRisk = 0;
		for (int i = 0; i < Parameters.fitnessSampleSize; i++) {
			Host h = getRandomHost();
			Phenotype[] history = h.getHistory();
			averageRisk += p.riskOfInfection(history);
		}
		averageRisk /= sampleSize;
		return averageRisk;

	}

	// draw a Poisson distributed number of samples and add them to the VirusSample
	// only sample after burnin is completed
	// assign fitness values.
	public void sample() {
		if (getI()>0 && Parameters.day >= Parameters.burnin) {
		
			double totalSamplingRate = Parameters.tipSamplingRate * Parameters.deltaT;
			if (Parameters.tipSamplingProportional) {
				totalSamplingRate *= getI();
			} 
			
			int samples = Random.nextPoisson(totalSamplingRate);
			for (int i = 0; i < samples; i++) {
				int index = getRandomI();
				Host h = infecteds.get(index);
				Virus v = h.getInfection();
				Phenotype p = v.getPhenotype();
				double risk = getAverageRisk(p);
				v.setFitness(risk);
				VirusTree.add(v);
			}	
		}
	}
		
	// through current infected population assigning ancestry as trunk
	public void makeTrunk() {
		for (int i = 0; i < getI(); i++) {
			Host h = infecteds.get(i);
			Virus v = h.getInfection();
			v.makeTrunk();
			while (v.getParent() != null) {
				v = v.getParent();
				if (v.isTrunk()) {
					break;
				} else {
					v.makeTrunk();
				}
			}
		}
	}	
	
	public void updateDiversity() {

		diversity = 0.0;
		tmrca = 0.0;
		antigenicDiversity = 0.0;		
		netau = 0.0;
		serialInterval = 0.0;
		
		if (getI()>1) { 
		
			double coalCount = 0.0;	
			double coalOpp = 0.0;
			double coalWindow = Parameters.netauWindow / 365.0;
			int sampleCount = Parameters.diversitySamplingCount;
			
			for (int i = 0; i < sampleCount; i++) {
				Virus vA = getRandomInfection();
				Virus vB = getRandomInfection();
				if (vA != null && vB != null) {
					double dist = vA.distance(vB);
					diversity += dist;
					if (dist > tmrca) {
						tmrca = dist;
					}
					antigenicDiversity += vA.antigenicDistance(vB);
					coalOpp += coalWindow;
					coalCount += vA.coalescence(vB, coalWindow);
					serialInterval += vA.serialInterval();
				}
			}	
		
			diversity /= sampleCount;
			tmrca /= 2.0;
			antigenicDiversity /= sampleCount;
			netau = coalOpp / coalCount;
			serialInterval /= sampleCount;
		
		}
		
	}	
		
	public void printState(PrintStream stream) {
		updateDiversity();
		stream.printf("\t%.4f\t%.4f\t%.4f\t%.5f\t%.4f\t%d\t%d\t%d\t%d\t%d", getDiversity(), getTmrca(), getNetau(), getSerialInterval(), getAntigenicDiversity(), getN(), getS(), getI(), getR(), getCases());
	}	
	
	public void printHeader(PrintStream stream) {
		stream.printf("\t%sDiversity\t%sTmrca\t%sNetau\t%sSerialInterval\t%sAntigenicDiversity\t%sN\t%sS\t%sI\t%sR\t%sCases", name, name, name, name, name, name, name, name, name, name);
	}
	
	// reset population to factory condition
	public void reset() {
	
		// clearing lists
		susceptibles.clear();
		infecteds.clear();
		recovereds.clear();
		
		int initialR = 0;
		if (Parameters.transcendental) {
			initialR = (int) ((double) Parameters.initialNs[deme] * Parameters.initialPrT);
		}
	
		// fill population with susceptibles
		int initialS = Parameters.initialNs[deme] - Parameters.initialI - initialR;
		for (int i = 0; i < initialS; i++) {
			Host h = new Host();			
			susceptibles.add(h);
		}
		
		// fill population with recovereds
		for (int i = 0; i < initialR; i++) {
			Host h = new Host();			
			recovereds.add(h);
		}		
		
		if (deme == Parameters.initialDeme - 1) {
		
			// infect some individuals
			for (int i = 0; i < 3*Parameters.initialI; i++) {
				Virus v = new Virus(Parameters.urVirus, deme);
				Host h = new Host(v);
				infecteds.add(h);
			}	
		
		}
		
	}
	
	public void printHostImmuneHistories(PrintStream stream, int n){
		// grab n random hosts and print their immune histories
		for (int i = 0; i < n; i++) {
			Host h = getRandomHost();
			stream.print(name + ":");
			h.printHistoryCoordinates(stream);
		}
	}
	
	public void printHostPopulation(PrintStream stream) {
		
		// step through susceptibles and print
		for (int i = 0; i < getS(); i++) {
			Host h = susceptibles.get(i);
			stream.print(deme + ":");
			h.printInfection(stream);
			stream.print(":");
			h.printHistory(stream);
			stream.println();
		}
		
		// step through infecteds and print
		for (int i = 0; i < getI(); i++) {
			Host h = infecteds.get(i);
			stream.print(deme + ":");
			h.printInfection(stream);
			stream.print(":");
			h.printHistory(stream);
			stream.println();
		}
		
		// step through recovereds and print
		for (int i = 0; i < getR(); i++) {
			Host h = recovereds.get(i);
			stream.print(deme + ":");
			h.printInfection(stream);
			stream.print(":");
			h.printHistory(stream);
			stream.println();
		}		
	
	}
				
}