#Set 8: Simulating the Spread of Disease and Virus Population Dynamics import time import random ''' Begin helper code ''' class NoChildException(Exception): """ NoChildException is raised by the reproduce() method in the SimpleVirus and ResistantVirus classes to indicate that a virus particle does not reproduce. You can use NoChildException as is, you do not need to modify/add any code. """ ''' End helper code ''' # # PROBLEM 2 # from copy import copy class SimpleVirus(object): """ Representation of a simple virus (does not model drug effects/resistance). """ def __init__(self, maxBirthProb, clearProb): """ Initialize a SimpleVirus instance, saves all parameters as attributes of the instance. maxBirthProb: Maximum reproduction probability (a float between 0-1) clearProb: Maximum clearance probability (a float between 0-1). """ self.max_birth_prob, self.clear_prob = maxBirthProb, clearProb def getMaxBirthProb(self): """ Returns the max birth probability. """ return self.max_birth_prob def getClearProb(self): """ Returns the clear probability. """ return self.clear_prob def doesClear(self): """ Stochastically determines whether this virus particle is cleared from the patient's body at a time step. returns: True with probability self.getClearProb and otherwise returns False. """ return random.random() < self.getClearProb() def reproduce(self, popDensity): """ Stochastically determines whether this virus particle reproduces at a time step. Called by the update() method in the Patient and TreatedPatient classes. The virus particle reproduces with probability self.getMaxBirthProb * (1 - popDensity). If this virus particle reproduces, then reproduce() creates and returns the instance of the offspring SimpleVirus (which has the same maxBirthProb and clearProb values as its parent). popDensity: the population density (a float), defined as the current virus population divided by the maximum population. returns: a new instance of the SimpleVirus class representing the offspring of this virus particle. The child should have the same maxBirthProb and clearProb values as this virus. Raises a NoChildException if this virus particle does not reproduce. """ if random.random() < self.getMaxBirthProb() * (1 - popDensity): return copy(self) else: raise NoChildException class Patient(object): """ Representation of a simplified patient. The patient does not take any drugs and his/her virus populations have no drug resistance. """ def __init__(self, viruses, maxPop): """ Initialization function, saves the viruses and maxPop parameters as attributes. viruses: the list representing the virus population (a list of SimpleVirus instances) maxPop: the maximum virus population for this patient (an integer) """ self.viruses, self.maximum_population = viruses, maxPop def getViruses(self): """ Returns the viruses in this Patient. """ return self.viruses def getMaxPop(self): """ Returns the max population. """ return self.maximum_population def getTotalPop(self): """ Gets the size of the current total virus population. returns: The total virus population (an integer) """ return len(self.getViruses()) def _new_viruses(self): """ - Determine whether each virus particle survives and updates the list of virus particles accordingly. """ new_viruses = [] for virus in self.getViruses(): if not virus.doesClear(): new_viruses.append(virus) return new_viruses def _try_reproduce(self, population_density): """ - Based on this value of population density, determine whether each virus particle should reproduce and add offspring virus particles to the list of viruses in this patient. """ new_viruses = [] for virus in self.viruses: try: new_viruses.append(virus.reproduce(population_density)) except NoChildException: pass return new_viruses def update(self): """ Update the state of the virus population in this patient for a single time step. update() should execute the following steps in this order: - Determine whether each virus particle survives and updates the list of virus particles accordingly. - The current population density is calculated. This population density value is used until the next call to update() - Based on this value of population density, determine whether each virus particle should reproduce and add offspring virus particles to the list of viruses in this patient. returns: The total virus population at the end of the update (an integer) """ self.viruses = self._new_viruses() max_population = float(self.getMaxPop()) #print len(self.viruses), 'survive' self.viruses.extend(self._try_reproduce(self.getTotalPop() / max_population)) return self.getTotalPop() class ResistantVirus(SimpleVirus): """ Representation of a virus which can have drug resistance. """ def __init__(self, maxBirthProb, clearProb, resistances, mutProb): """ Initialize a ResistantVirus instance, saves all parameters as attributes of the instance. maxBirthProb: Maximum reproduction probability (a float between 0-1) clearProb: Maximum clearance probability (a float between 0-1). resistances: A dictionary of drug names (strings) mapping to the state of this virus particle's resistance (either True or False) to each drug. e.g. {'guttagonol':False, 'srinol':False}, means that this virus particle is resistant to neither guttagonol nor srinol. mutProb: Mutation probability for this virus particle (a float). This is the probability of the offspring acquiring or losing resistance to a drug. """ SimpleVirus.__init__(self, maxBirthProb, clearProb) self.resistances, self.mutProb = resistances, mutProb def isResistantTo(self, drug): """ Get the state of this virus particle's resistance to a drug. This method is called by getResistPop() in TreatedPatient to determine how many virus particles have resistance to a drug. drug: The drug (a string) returns: True if this virus instance is resistant to the drug, False otherwise. """ return self.resistances.get(drug, False) def reproduce(self, popDensity, activeDrugs): """ Stochastically determines whether this virus particle reproduces at a time step. Called by the update() method in the TreatedPatient class. A virus particle will only reproduce if it is resistant to ALL the drugs in the activeDrugs list. For example, if there are 2 drugs in the activeDrugs list, and the virus particle is resistant to 1 or no drugs, then it will NOT reproduce. Hence, if the virus is resistant to all drugs in activeDrugs, then the virus reproduces with probability: self.getMaxBirthProb * (1 - popDensity). If this virus particle reproduces, then reproduce() creates and returns the instance of the offspring ResistantVirus (which has the same maxBirthProb and clearProb values as its parent). The offspring virus will have the same maxBirthProb, clearProb, and mutProb as the parent. For each drug resistance trait of the virus (i.e. each key of self.resistances), the offspring has probability 1-mutProb of inheriting that resistance trait from the parent, and probability mutProb of switching that resistance trait in the offspring. For example, if a virus particle is resistant to guttagonol but not srinol, and self.mutProb is 0.1, then there is a 10% chance that that the offspring will lose resistance to guttagonol and a 90% chance that the offspring will be resistant to guttagonol. There is also a 10% chance that the offspring will gain resistance to srinol and a 90% chance that the offspring will not be resistant to srinol. popDensity: the population density (a float), defined as the current virus population divided by the maximum population activeDrugs: a list of the drug names acting on this virus particle (a list of strings). returns: a new instance of the ResistantVirus class representing the offspring of this virus particle. The child should have the same maxBirthProb and clearProb values as this virus. Raises a NoChildException if this virus particle does not reproduce. """ if (all(self.isResistantTo(drug) for drug in activeDrugs) and random.random() < self.getMaxBirthProb() * (1 - popDensity)): resistances = copy(self.resistances) for drug in self.resistances: if random.random() < self.mutProb: resistances[drug] = not resistances[drug] return ResistantVirus(self.getMaxBirthProb(), self.getClearProb(), resistances, self.mutProb) raise NoChildException class TreatedPatient(Patient): """ Representation of a patient. The patient is able to take drugs and his/her virus population can acquire resistance to the drugs he/she takes. """ def __init__(self, viruses, maxPop): """ Initialization function, saves the viruses and maxPop parameters as attributes. Also initializes the drugs being administered (which should initially include no drugs). viruses: The list representing the virus population (a list of virus instances) maxPop: The maximum virus population for this patient (an integer) """ Patient.__init__(self, viruses, maxPop) self.drugs = set() def addPrescription(self, newDrug): """ Administer a drug to this patient. After a prescription is added, the drug acts on the virus population for all subsequent time steps. If the newDrug is already prescribed to this patient, the method has no effect. newDrug: The name of the drug to administer to the patient (a string). postcondition: The drugs being administered to a patient is updated """ self.drugs.add(newDrug) def getPrescriptions(self): """ Returns the drugs that are being administered to this patient. returns: The drug names (strings) being administered to this patient. """ return self.drugs def getResistPop(self, drugResist): """ Get the population of virus particles resistant to the drugs listed in drugResist. drugResist: Which drug resistances to include in the population (a list of strings - e.g. ['guttagonol'] or ['guttagonol', 'srinol']) returns: The population of viruses (an integer) with resistances to all drugs in the drugResist list. """ return sum(1 for virus in self.viruses if all(virus.isResistantTo(drug) for drug in drugResist)) def _try_reproduce(self, population_density): """ - Based on this value of population density, determine whether each virus particle should reproduce and add offspring virus particles to the list of viruses in this patient. The list of drugs being administered should be accounted for in the determination of whether each virus particle reproduces. """ new_viruses = [] for virus in self.viruses: try: new_viruses.append(virus.reproduce(population_density, self.getPrescriptions())) except NoChildException: pass return new_viruses def col(mat,j): v=[] rows=len(mat) for i in xrange(rows): v.append(mat[i][j]) return v def transpose(m): n = [] cols=len(m[0]) for i in xrange(cols): n.append(col(m,i)) return n # # PROBLEM 5 # def simulationWithDrug(numViruses, maxPop, maxBirthProb, clearProb, resistances, mutProb, numTrials, start=150, timing=False): """ Runs simulations and plots graphs for problem 5. For each of numTrials trials, instantiates a patient, runs a simulation for 150 timesteps, adds guttagonol, and runs the simulation for an additional 150 timesteps. At the end plots the average virus population size (for both the total virus population and the guttagonol-resistant virus population) as a function of time. numViruses: number of ResistantVirus to create for patient (an integer) maxPop: maximum virus population for patient (an integer) maxBirthProb: Maximum reproduction probability (a float between 0-1) clearProb: maximum clearance probability (a float between 0-1) resistances: a dictionary of drugs that each ResistantVirus is resistant to (e.g., {'guttagonol': False}) mutProb: mutation probability for each ResistantVirus particle (a float between 0-1). numTrials: number of simulation runs to execute (an integer) """ simulations = [] resistant_pop =[] if timing: t0 = time.clock() for trial in range(numTrials): population = [ResistantVirus(maxBirthProb, clearProb, resistances, mutProb) for _ in range(numViruses)] patient = TreatedPatient(population, maxPop) current = [] resistant = [] if not trial % 10: print trial, for simulation in range(300): if simulation == start: patient.addPrescription("guttagonol") ## for drug in resistances: ## patient.addPrescription(drug) current.append(float(patient.update())) resistant.append(float(patient.getResistPop(['guttagonol']))) simulations.append(current) resistant_pop.append(resistant) if timing: print time.clock() - t0, 's' else: print x = [sum(step)/len(step) for step in transpose(simulations)] y = [sum(resist)/len(resist) for resist in transpose(resistant_pop)] return x,y ## print x ## print y if __name__ == '__main__': random.seed(0) x, y = simulationWithDrug(100, 1000, 0.1, 0.05, {'guttagonol': False}, 0.005, 100, timing=True) print x print y