def test_stochastic_well_mixed(self):
S, E, I, R = sympy.symbols("S E I R")
N = 75000
tmax = 100
model = SymbolicEpiModel([S, E, I, R], N)
model.set_processes([
(S, I, 2, E, I),
(I, 1, R),
(E, 1, I),
])
model.set_initial_conditions({S: N - 100, I: 100})
tt = np.linspace(0, tmax, 10)
result_int = model.integrate(tt)
t, result_sim = model.simulate(tmax,
sampling_dt=1,
return_compartments=[S, R])
for c, res in result_sim.items():
#print(c, np.abs(1-res[-1]/result_int[c][-1]))
#print(c, np.abs(1-res[-1]/result_sim[c][-1]))
assert (np.abs(1 - res[-1] / result_int[c][-1]) < 0.05)
def symbolic_simulation_temporally_forced():
from epipack import SymbolicEpiModel
import sympy as sy
from epipack.plottools import plot
import numpy as np
S, I, R, eta, rho, omega, t, T = \
sy.symbols("S I R eta rho omega t T")
N = 1000
SIRS = SymbolicEpiModel([S,I,R],N)\
.set_processes([
(S, I, 3+sy.cos(2*sy.pi*t/T), I, I),
(I, rho, R),
(R, omega, S),
])
SIRS.set_parameter_values({
rho: 1,
omega: 1 / 14,
T: 100,
})
SIRS.set_initial_conditions({S: N - 100, I: 100})
_t = np.linspace(0, 150, 1000)
result = SIRS.integrate(_t)
t_sim, result_sim = SIRS.simulate(max(_t))
ax = plot(_t, result)
plot(t_sim, result_sim, ax=ax)
ax.get_figure().savefig('symbolic_model_time_varying_rate.png', dpi=300)
def test_changing_population_size(self):
A, B, C, t = sympy.symbols("A B C t")
epi = SymbolicEpiModel([A, B, C],
10,
correct_for_dynamical_population_size=True)
epi.set_initial_conditions({A: 5, B: 5})
epi.set_processes([
(A, B, 1, C),
], allow_nonzero_column_sums=True)
dydt = epi.dydt()
assert (dydt[0] == -1 * A * B / (A + B + C))
_, res = epi.simulate(1e9)
assert (res[C][-1] == 5)
epi.set_processes([
(None, 1 + sympy.log(1 + t), A),
(A, 1 + sympy.log(1 + t), B),
(B, 1 + sympy.log(1 + t), None),
],
allow_nonzero_column_sums=True)
rates, comp_changes = epi.get_numerical_event_and_rate_functions()
_, res = epi.simulate(200, sampling_dt=0.05)
vals = np.concatenate([res[A][_ > 10], res[B][_ > 10]])
rv = poisson(vals.mean())
measured, bins = np.histogram(vals,
bins=np.arange(10) - 0.5,
density=True)
theory = [
rv.pmf(i) for i in range(0,
len(bins) - 1) if measured[i] > 0
]
experi = [
measured[i] for i in range(0,
len(bins) - 1) if measured[i] > 0
]
# make sure the kullback-leibler divergence is below some threshold
assert (entropy(theory, experi) < 2e-3)
assert (np.median(res[A]) == 1)