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Example Homework Assignment from Introductory Python course 6.00
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# Problem Set 7: Simulating the Spread of Disease, Body Temperature and Virus Population Dynamics | |
# Name: Kuan Butts | |
# Time: 22:00 | |
import numpy | |
import random | |
import pylab | |
# for checking work from prob. 3, 4, 5, 6 | |
#from ps7_precompiled_27 import * | |
#from ps7_temperature import * | |
#from ps7_precompiled_27 import * | |
''' | |
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 should use NoChildException as is, you do not need to | |
modify/add any code. | |
""" | |
''' | |
End helper code | |
''' | |
# | |
# PROBLEM 2 | |
# | |
class SimpleVirus(object): | |
""" | |
Representation of a simple virus (does not model drug effects/resistance). | |
""" | |
def __init__(self, max_birth_prob, clear_prob): | |
""" | |
Initialize a SimpleVirus instance, saves all parameters as attributes | |
of the instance. | |
max_birth_prob: Maximum reproduction probability (a float between 0-1) | |
clear_prob: Maximum clearance probability (a float between 0-1). | |
""" | |
self.max_birth_prob = max_birth_prob | |
self.clear_prob = clear_prob | |
def does_clear(self): | |
""" Stochastically determines whether this virus particle is cleared from the | |
patient's body at a time step. | |
returns: True with probability self.clear_prob and otherwise returns | |
False. | |
""" | |
if random.random() < self.clear_prob: | |
return True | |
else: | |
return False | |
def reproduce(self, pop_density): | |
""" | |
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.max_birth_prob * (1 - pop_density). | |
If this virus particle reproduces, then reproduce() creates and returns | |
the instance of the offspring SimpleVirus (which has the same | |
max_birth_prob and clear_prob values as its parent). | |
pop_density: 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 | |
max_birth_prob and clear_prob values as this virus. Raises a | |
NoChildException if this virus particle does not reproduce. | |
""" | |
if random.random() < self.max_birth_prob * (1 - pop_density): | |
return SimpleVirus(self.max_birth_prob, self.clear_prob) | |
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, max_pop): | |
""" | |
Initialization function, saves the viruses and max_pop parameters as | |
attributes. | |
viruses: the list representing the virus population (a list of | |
SimpleVirus instances) | |
max_pop: the maximum virus population for this patient (an integer) | |
for Problem 4: temperature : the body temperature of the patient, which is initialized to 98 Fahrenheit. | |
""" | |
self.viruses = viruses | |
self.max_pop = max_pop | |
self.temperature = 98 | |
def get_total_pop(self): | |
""" | |
Gets the size of the current total virus population. | |
returns: The total virus population (an integer) | |
""" | |
return len(self.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) | |
- For Problem 4: Assign a value for the temperature. The value should be drawn | |
from a Gaussian Distribution that has a mean of 98 Fahrenheit and | |
a standard devaition of 1 Fahrenheit. You can use "random.gauss(98,1)" | |
- For Problem 4: check if the current temperature is greater than 100 Fahrenheit. | |
If the temperature is greater than 100 Fahrenheit then reduce the | |
virus population by 50%. | |
""" | |
survive_list = [] | |
current_temp = self.temperature | |
current_temp = random.gauss(98, 1) | |
# for loop to append only viruses that clear .does_clear | |
for virus in self.viruses: | |
if virus.does_clear() == False: | |
survive_list.append(virus) | |
reproduce_list = [] | |
pop_density = self.get_total_pop()/float(self.max_pop) | |
# for loop to add viruses that reproduce | |
for survived_virus in self.viruses: | |
try: | |
survived_virus.reproduce(pop_density) | |
reproduce_list.append(survived_virus) | |
except NoChildException: | |
pass | |
# add the survivors to the reproduced | |
self.viruses = survive_list + reproduce_list | |
temp_modify = [] | |
# now a for loop to check for temperature level | |
if current_temp >= 100: | |
for i in range(int((len(self.viruses))/2)): | |
temp_modify.append(self.viruses[i]) | |
self.viruses = temp_modify | |
return len(self.viruses) | |
# | |
# PROBLEM 3 | |
# | |
def simulation_without_drug(num_viruses, max_pop, max_birth_prob, clear_prob, | |
num_trials): | |
""" | |
Run the simulation and plot the graph for problem 3 (no drugs are used, | |
viruses do not have any drug resistance). | |
For each of num_trials trials, instantiates a patient, runs a simulation | |
for 300 timesteps, and plots the average virus population size as a | |
function of time. | |
num_viruses: number of SimpleVirus to create for patient (an integer) | |
max_pop: maximum virus population for patient (an integer) | |
max_birth_prob: Maximum reproduction probability (a float between 0-1) | |
clear_prob: Maximum clearance probability (a float between 0-1) | |
num_trials: number of simulation runs to execute (an integer) | |
""" | |
# making a variable just in case we have to change later | |
num_timesteps = 300 | |
# create a list that can have results added to it for averaging at end | |
trial_results = [] | |
for values in range(num_timesteps): | |
trial_results.append(0) | |
# instantiate patients through list and run them through timesteps | |
for case in range(num_trials): | |
virus_init_list = [] | |
for num in range(num_viruses): | |
virus_init_list.append(SimpleVirus(max_birth_prob, clear_prob)) | |
instance_patient = Patient(virus_init_list, max_pop) | |
for update_instance in range(num_timesteps): | |
trial_results[update_instance] += instance_patient.update() | |
for step in range(len(trial_results)): | |
trial_results[step] = trial_results[step]/float(num_trials) | |
pylab.plot(range(num_timesteps), trial_results) | |
pylab.title("Average size of the virus population as a function of time") | |
pylab.legend(('Average size of virus population')) | |
pylab.xlabel("Time (Hours)") | |
pylab.ylabel("Average population") | |
pylab.show() | |
# | |
# PROBLEM 4 | |
# | |
class ResistantVirus(SimpleVirus): | |
""" | |
Representation of a virus which can have drug resistance. | |
""" | |
def __init__(self, max_birth_prob, clear_prob, resistances, mut_prob): | |
""" | |
Initialize a ResistantVirus instance, saves all parameters as attributes | |
of the instance. | |
max_birth_prob: Maximum reproduction probability (a float between 0-1) | |
clear_prob: 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. {'fredonol':False, 'anadex':False}, means that this virus | |
particle is resistant to neither fredonol nor anadex. | |
mut_prob: Mutation probability for this virus particle (a float). This is | |
the probability of the offspring acquiring or losing resistance to a drug. | |
""" | |
# do I need to bring in simplevirus and then re-assosciate all variables? whats the pt? | |
SimpleVirus.__init__(self, max_birth_prob, clear_prob) | |
self.resistances = resistances | |
self.mut_prob = mut_prob | |
def is_resistant_to(self, drug): | |
""" | |
Get the state of this virus particle's resistance to a drug. This method | |
is called by get_resist_pop() 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. | |
""" | |
try: | |
return self.resistances[drug] | |
except KeyError: | |
return False | |
def reproduce(self, pop_density, active_drugs): | |
""" | |
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 active_drugs list. For example, if there are 2 drugs in the | |
active_drugs 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 active_drugs, then the virus reproduces with probability: | |
self.max_birth_prob * (1 - pop_density). | |
If this virus particle reproduces, then reproduce() creates and returns | |
the instance of the offspring ResistantVirus (which has the same | |
max_birth_prob and clear_prob values as its parent). | |
For each drug resistance trait of the virus (i.e. each key of | |
self.resistances), the offspring has probability 1-mut_prob of | |
inheriting that resistance trait from the parent, and probability | |
mut_prob of switching that resistance trait in the offspring. | |
For example, if a virus particle is resistant to fredonol but not | |
anadex, and self.mut_prob is 0.1, then there is a 10% chance that | |
that the offspring will lose resistance to fredonol and a 90% | |
chance that the offspring will be resistant to fredonol. | |
There is also a 10% chance that the offspring will gain resistance to | |
anadex and a 90% chance that the offspring will not be resistant to | |
anadex. | |
pop_density: the population density (a float), defined as the current | |
virus population divided by the maximum population | |
active_drugs: 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 | |
max_birth_prob and clear_prob values as this virus. Raises a | |
NoChildException if this virus particle does not reproduce. | |
""" | |
# check if resistant to all drugs in the active_drugs list | |
check_reproduce = 0 | |
for drug in active_drugs: | |
if (self.is_resistant_to(drug) == True): | |
pass | |
else: | |
check_reproduce += 1 | |
raise NoChildException() | |
if (check_reproduce == 0): | |
# reproduce with the below probability | |
if random.random() < (self.max_birth_prob * (1 - pop_density)): | |
passed_resistance = {} | |
for elem in self.resistances: | |
if (self.is_resistant_to(elem) == True): | |
if random.random() <= self.mut_prob: | |
passed_resistance[elem] = False | |
else: | |
passed_resistance[elem] = True | |
elif (self.is_resistant_to(elem) == False): | |
if random.random() <= self.mut_prob: | |
passed_resistance[elem] = True | |
else: | |
passed_resistance[elem] = False | |
return ResistantVirus(self.max_birth_prob, self.clear_prob, passed_resistance, self.mut_prob) | |
else: | |
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, max_pop): | |
""" | |
Initialization function, saves the viruses and max_pop parameters as | |
attributes. Also initializes the list of drugs being administered | |
(which should initially include no drugs). | |
viruses: The list representing the virus population (a list of | |
virus instances) | |
max_pop: The maximum virus population for this patient (an integer) | |
""" | |
### always do this? ...even if I am going to make all new classes for treatedpatient? why? | |
Patient.__init__(self, viruses, max_pop) | |
self.druglist = [] | |
# why does druglist have to have "self." when it is not part of init entered vars? | |
def add_prescription(self, new_drug): | |
""" | |
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 | |
new_drug is already prescribed to this patient, the method has no effect. | |
new_drug: The name of the drug to administer to the patient (a string). | |
postcondition: The list of drugs being administered to a patient is updated | |
""" | |
if new_drug in self.druglist: | |
pass | |
else: | |
self.druglist.append(new_drug) | |
def get_prescriptions(self): | |
""" | |
Returns the drugs that are being administered to this patient. | |
returns: The list of drug names (strings) being administered to this | |
patient. | |
""" | |
return self.druglist | |
def get_resist_pop(self, drug_resist): | |
""" | |
Get the population of virus particles resistant to the drugs listed in | |
drug_resist. | |
drug_resist: Which drug resistances to include in the population (a list | |
of strings - e.g. ['fredonol'] or ['fredonol', 'anadex']) | |
returns: The population of viruses (an integer) with resistances to all | |
drugs in the drug_resist list. | |
""" | |
resistant_pop = 0 | |
for virus in self.viruses: | |
resist_check = 0 | |
for drug in drug_resist: | |
if virus.is_resistant_to(drug): | |
resist_check += 1 | |
if len(drug_resist) == resist_check: | |
resistant_pop += 1 | |
return resistant_pop | |
def update(self): | |
""" | |
Update the state of the virus population in this patient for a single | |
time step. update() should execute these actions in order: | |
- Determine whether each virus particle survives and update the list of | |
virus particles accordingly | |
- The current population density is calculated. This population density | |
value is used until the next call to update(). | |
- 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. | |
returns: The total virus population at the end of the update (an | |
integer) | |
""" | |
survive_list = [] | |
# for loop to append only viruses that clear .does_clear | |
for virus in self.viruses: | |
if virus.does_clear() == False: | |
survive_list.append(virus) | |
reproduce_list = [] | |
pop_density = (self.get_total_pop())/(float(self.max_pop)) | |
# for loop to add viruses that reproduce | |
for survived_virus in survive_list: | |
try: | |
possible_v = survived_virus.reproduce(pop_density, self.druglist) | |
reproduce_list.append(possible_v) | |
except NoChildException: | |
pass | |
# add the survivors to the reproduced | |
self.viruses = survive_list + reproduce_list | |
return len(self.viruses) | |
# | |
# PROBLEM 5 | |
# | |
def simulation_with_drug(num_viruses, max_pop, max_birth_prob, clear_prob, resistances, | |
mut_prob, num_trials): | |
""" | |
Runs simulations and plots graphs for problem 5. | |
For each of num_trials trials, instantiates a patient, runs a simulation for | |
120 timesteps, adds fredonol, and runs the simulation for an additional | |
180 timesteps. At the end plots the average virus population size | |
(for both the total virus population and the fredonol-resistant virus | |
population) as a function of time. | |
As mentioned above create ONE plot that has the following 2 curves on it. | |
(i) The average total virus population over time | |
(ii) The average population of ìfredonolî-resistant virus population over time. | |
Note: The 2 curves should be on the same plot. | |
num_viruses: number of ResistantVirus to create for patient (an integer) | |
max_pop: maximum virus population for patient (an integer) | |
max_birth_prob: Maximum reproduction probability (a float between 0-1) | |
clear_prob: maximum clearance probability (a float between 0-1) | |
resistances: a dictionary of drugs that each ResistantVirus is resistant to | |
(e.g., {'fredonol': False}) | |
mut_prob: mutation probability for each ResistantVirus particle | |
(a float between 0-1). | |
num_trials: number of simulation runs to execute (an integer) | |
""" | |
# making a variable for timesteps | |
num_timesteps = 300 | |
timesteps_p1 = 120 | |
timesteps_p2 = 180 | |
### trial part 1 | |
# create a list that can have results added to it for averaging at end | |
trial_results = [] | |
for values in range(num_timesteps): | |
trial_results.append(0) | |
# and a list for the resistancies to plot fredonol-resistant virus population | |
resistancies = [] | |
for values in range(num_timesteps): | |
resistancies.append(0) | |
# instantiate patients through list and run them through timesteps | |
for case in range(num_trials): | |
virus_init_list = [] | |
for num in range(num_viruses): | |
virus_init_list.append(ResistantVirus(max_birth_prob, clear_prob, resistances, mut_prob)) | |
instance_patient = TreatedPatient(virus_init_list, max_pop) | |
for update_instance in range(timesteps_p1): | |
trial_results[update_instance] += instance_patient.update() | |
resistancies[update_instance] += instance_patient.get_resist_pop(['fredonol']) | |
instance_patient.add_prescription("fredonol") | |
for update_instance2 in range(timesteps_p2): | |
trial_results[update_instance2 + timesteps_p1] += instance_patient.update() | |
resistancies[update_instance2 + timesteps_p1] += instance_patient.get_resist_pop(['fredonol']) | |
# get average for total population | |
for step in range(len(trial_results)): | |
trial_results[step] = trial_results[step]/float(num_trials) | |
# get average for resistant populations | |
for step in range(len(resistancies)): | |
resistancies[step] = resistancies[step]/float(num_trials) | |
pylab.plot(range(num_timesteps), trial_results) | |
pylab.plot(range(num_timesteps), resistancies) | |
pylab.title("Average size of the virus population as a function of time") | |
pylab.legend(('Average size of virus population', 'Average size of fredonol resistant population')) | |
pylab.xlabel("Time (Hours)") | |
pylab.ylabel("Average population") | |
pylab.show() | |
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