def test_full_eval_range(self):
"""
Test if ODEModels can be evaluated at t < t_initial.
A bit of a no news is good news test.
"""
tdata = np.array([0, 10, 26, 44, 70, 120])
adata = 10e-4 * np.array([54, 44, 34, 27, 20, 14])
a, b, t = variables('a, b, t')
k, a0 = parameters('k, a0')
k.value = 0.01
t0 = tdata[2]
a0 = adata[2]
b0 = 0.02729855 # Obtained from evaluating from t=0.
model_dict = {
D(a, t): - k * a**2,
D(b, t): k * a**2,
}
ode_model = ODEModel(model_dict, initial={t: t0, a: a0, b: b0})
fit = Fit(ode_model, t=tdata, a=adata, b=None)
ode_result = fit.execute()
self.assertGreater(ode_result.r_squared, 0.95, 4)
# Now start from a timepoint that is not in the t-array such that it
# triggers another pathway to be taken in integrating it.
# Again, no news is good news.
ode_model = ODEModel(model_dict, initial={t: t0 + 1e-5, a: a0, b: b0})
fit = Fit(ode_model, t=tdata, a=adata, b=None)
ode_result = fit.execute()
self.assertGreater(ode_result.r_squared, 0.95, 4)
def test_single_eval(self):
"""
Eval an ODEModel at a single value rather than a vector.
"""
x, y, t = variables('x, y, t')
k, = parameters('k') # C is the integration constant.
# The harmonic oscillator as a system, >1st order is not supported yet.
harmonic_dict = {
D(x, t): - k * y,
D(y, t): k * x,
}
# Make a second model to prevent caching of integration results.
# This also means harmonic_dict should NOT be a Model object.
harmonic_model_array = ODEModel(harmonic_dict, initial={t: 0.0, x: 1.0, y: 0.0})
harmonic_model_points = ODEModel(harmonic_dict, initial={t: 0.0, x: 1.0, y: 0.0})
tdata = np.linspace(-100, 100, 101)
X, Y = harmonic_model_array(t=tdata, k=0.1)
# Shuffle the data to prevent using the result at time t to calculate
# t+dt
random_order = np.random.permutation(len(tdata))
for idx in random_order:
t = tdata[idx]
X_val = X[idx]
Y_val = Y[idx]
X_point, Y_point = harmonic_model_points(t=t, k=0.1)
self.assertAlmostEqual(X_point[0], X_val)
self.assertAlmostEqual(Y_point[0], Y_val)
def test_pickle():
"""
Make sure models can be pickled are preserved when pickling
"""
a, b = parameters('a, b')
x, y = variables('x, y')
exact_model = Model({y: a * x ** b})
constraint = Model.as_constraint(Eq(a, b), exact_model)
num_model = CallableNumericalModel(
{y: a * x ** b}, independent_vars=[x], params=[a, b]
)
connected_num_model = CallableNumericalModel(
{y: a * x ** b}, connectivity_mapping={y: {x, a, b}}
)
# Test if lsoda args and kwargs are pickled too
ode_model = ODEModel({D(y, x): a * x + b}, {x: 0.0}, 3, 4, some_kwarg=True)
models = [exact_model, constraint, num_model, ode_model, connected_num_model]
for model in models:
new_model = pickle.loads(pickle.dumps(model))
# Compare signatures
assert model.__signature__ == new_model.__signature__
# Trigger the cached vars because we compare `__dict__` s
model.vars
new_model.vars
# Explicitly make sure the connectivity mapping is identical.
assert model.connectivity_mapping == new_model.connectivity_mapping
if not isinstance(model, ODEModel):
model.function_dict
model.vars_as_functions
new_model.function_dict
new_model.vars_as_functions
assert model.__dict__ == new_model.__dict__
def test_simple_kinetics(self):
"""
Simple kinetics data to test fitting
"""
tdata = np.array([10, 26, 44, 70, 120])
adata = 10e-4 * np.array([44, 34, 27, 20, 14])
a, b, t = variables('a, b, t')
k, a0 = parameters('k, a0')
k.value = 0.01
# a0.value, a0.min, a0.max = 54 * 10e-4, 40e-4, 60e-4
a0 = 54 * 10e-4
model_dict = {
D(a, t): -k * a**2,
D(b, t): k * a**2,
}
ode_model = ODEModel(model_dict, initial={t: 0.0, a: a0, b: 0.0})
fit = ConstrainedNumericalLeastSquares(ode_model,
t=tdata,
a=adata,
b=None)
fit_result = fit.execute(tol=1e-9)
self.assertAlmostEqual(fit_result.value(k), 4.302875e-01, 4)
self.assertTrue(fit_result.stdev(k) is None)
def test_simple_kinetics(self):
"""
Simple kinetics data to test fitting
"""
tdata = np.array([10, 26, 44, 70, 120])
adata = 10e-4 * np.array([44, 34, 27, 20, 14])
a, b, t = variables('a, b, t')
k, a0 = parameters('k, a0')
k.value = 0.01
# a0.value, a0.min, a0.max = 54 * 10e-4, 40e-4, 60e-4
a0 = 54 * 10e-4
model_dict = {
D(a, t): -k * a**2,
D(b, t): k * a**2,
}
ode_model = ODEModel(model_dict, initial={t: 0.0, a: a0, b: 0.0})
# Generate some data
tvec = np.linspace(0, 500, 1000)
fit = NumericalLeastSquares(ode_model, t=tdata, a=adata, b=None)
fit_result = fit.execute()
# print(fit_result)
self.assertAlmostEqual(fit_result.value(k), 4.302875e-01, 4)
self.assertAlmostEqual(fit_result.stdev(k), 6.447068e-03, 4)
fit = Fit(ode_model, t=tdata, a=adata, b=None)
fit_result = fit.execute()
# print(fit_result)
self.assertAlmostEqual(fit_result.value(k), 4.302875e-01, 4)
self.assertTrue(np.isnan(fit_result.stdev(k)))
def test_polgar(self):
"""
Analysis of data published here:
This whole ODE support was build to do this analysis in the first place
"""
a, b, c, d, t = variables('a, b, c, d, t')
k, p, l, m = parameters('k, p, l, m')
a0 = 10
b = a0 - d + a
model_dict = {
D(d, t): l * c * b - m * d,
D(c, t): k * a * b - p * c - l * c * b + m * d,
D(a, t): -k * a * b + p * c,
}
ode_model = ODEModel(model_dict,
initial={
t: 0.0,
a: a0,
c: 0.0,
d: 0.0
})
# Generate some data
tdata = np.linspace(0, 3, 1000)
# Eval
AA, AAB, BAAB = ode_model(t=tdata, k=0.1, l=0.2, m=.3, p=0.3)
def modeling(pdata, xdata, sdata, tdata):
X, S, P, t = variables('X, S, P, t')
k = Parameter('k', 0.1)
umax = Parameter('umax', min=0.06, max=0.25)
Ki = Parameter('Ki', min=10, max=80)
Ks = Parameter('Ks', min=0.5, max=8)
Kip = Parameter('Kip', min=10, max=17)
mx = Parameter('mx', min=0.001, max=0.1)
alpha = Parameter('alpha', min=0.1, max=2.4)
beta = Parameter('beta', min=0.001, max=1.2)
X0 = 0.01
S0 = 50
P0 = 0.01
model_dict = {
D(X, t): umax * S / (Ks + S) * X,
D(S, t): -umax * S / (Ks + S) * X,
D(P, t): umax * S / (Ks + S)
}
ode_model_monod = ODEModel(model_dict,
initial={
t: 0.0,
X: X0,
S: S0,
P: P0
})
fit = Fit(ode_model_monod, t=tdata, X=xdata, S=sdata, P=pdata)
fit_result = fit.execute()
return ode_model_monod, fit_result
def test_simple_kinetics(self):
"""
Simple kinetics data to test fitting
"""
tdata = np.array([10, 26, 44, 70, 120])
adata = 10e-4 * np.array([44, 34, 27, 20, 14])
a, b, t = variables('a, b, t')
k, a0 = parameters('k, a0')
k.value = 0.01
# a0.value, a0.min, a0.max = 54 * 10e-4, 40e-4, 60e-4
a0 = 54 * 10e-4
model_dict = {
D(a, t): - k * a**2,
D(b, t): k * a**2,
}
ode_model = ODEModel(model_dict, initial={t: 0.0, a: a0, b: 0.0})
# Analytical solution
model = Model({a: 1 / (k * t + 1 / a0)})
fit = Fit(model, t=tdata, a=adata)
fit_result = fit.execute()
fit = Fit(ode_model, t=tdata, a=adata, b=None, minimizer=MINPACK)
ode_result = fit.execute()
self.assertAlmostEqual(ode_result.value(k) / fit_result.value(k), 1.0, 4)
self.assertAlmostEqual(ode_result.stdev(k) / fit_result.stdev(k), 1.0, 4)
self.assertAlmostEqual(ode_result.r_squared / fit_result.r_squared, 1, 4)
fit = Fit(ode_model, t=tdata, a=adata, b=None)
ode_result = fit.execute()
self.assertAlmostEqual(ode_result.value(k) / fit_result.value(k), 1.0, 4)
self.assertAlmostEqual(ode_result.stdev(k) / fit_result.stdev(k), 1.0, 4)
self.assertAlmostEqual(ode_result.r_squared / fit_result.r_squared, 1, 4)
def test_known_solution(self):
p, c1 = parameters('p, c1')
y, t = variables('y, t')
p.value = 3.0
model_dict = {
D(y, t): - p * y,
}
# Lets say we know the exact solution to this problem
sol = Model({y: exp(- p * t)})
# Generate some data
tdata = np.linspace(0, 3, 10001)
ydata = sol(t=tdata, p=3.22)[0]
ydata += np.random.normal(0, 0.005, ydata.shape)
ode_model = ODEModel(model_dict, initial={t: 0.0, y: ydata[0]})
fit = Fit(ode_model, t=tdata, y=ydata)
ode_result = fit.execute()
c1.value = ydata[0]
fit = Fit(sol, t=tdata, y=ydata)
fit_result = fit.execute()
self.assertAlmostEqual(ode_result.value(p) / fit_result.value(p), 1, 2)
self.assertAlmostEqual(ode_result.r_squared / fit_result.r_squared, 1, 4)
self.assertAlmostEqual(ode_result.stdev(p) / fit_result.stdev(p), 1, 3)
def setUpClass(cls):
# First order reaction kinetics. Data taken from http://chem.libretexts.org/Core/Physical_Chemistry/Kinetics/Rate_Laws/The_Rate_Law
tdata = np.array([
0, 0.9184, 9.0875, 11.2485, 17.5255, 23.9993, 27.7949, 31.9783,
35.2118, 42.973, 46.6555, 50.3922, 55.4747, 61.827, 65.6603,
70.0939
])
concentration_A = np.array([
0.906, 0.8739, 0.5622, 0.5156, 0.3718, 0.2702, 0.2238, 0.1761,
0.1495, 0.1029, 0.086, 0.0697, 0.0546, 0.0393, 0.0324, 0.026
])
concentration_B = np.max(concentration_A) - concentration_A
# Define our ODE model
A, B, t = variables('A, B, t')
k = Parameter('k')
model_dict = {D(A, t): -k * A**2, D(B, t): k * A**2}
model = ODEModel(model_dict,
initial={
t: tdata[0],
A: concentration_A[0],
B: 0
})
cls.guess = interactive_guess.InteractiveGuess(model,
A=concentration_A,
B=concentration_B,
t=tdata,
n_points=250)
def test_initial_parameters():
"""
Identical to test_polgar, but with a0 as free Parameter.
"""
a, b, c, d, t = variables('a, b, c, d, t')
k, p, l, m = parameters('k, p, l, m')
a0 = Parameter('a0', min=0, value=10, fixed=True)
c0 = Parameter('c0', min=0, value=0.1)
b = a0 - d + a
model_dict = {
D(d, t): l * c * b - m * d,
D(c, t): k * a * b - p * c - l * c * b + m * d,
D(a, t): - k * a * b + p * c,
}
ode_model = ODEModel(model_dict, initial={t: 0.0, a: a0, c: c0, d: 0.0})
# Generate some data
tdata = np.linspace(0, 3, 1000)
# Eval
AA, AAB, BAAB = ode_model(t=tdata, k=0.1, l=0.2, m=.3, p=0.3, a0=10, c0=0)
fit = Fit(ode_model, t=tdata, a=AA, c=AAB, d=BAAB)
results = fit.execute()
print(results)
assert results.value(a0) == pytest.approx(10, abs=1e-8)
assert results.value(c0) == pytest.approx(0, abs=1e-8)
assert ode_model.params == [a0, c0, k, l, m, p]
assert ode_model.initial_params == [a0, c0]
assert ode_model.model_params == [a0, k, l, m, p]
def test_van_der_pol():
"""
http://hplgit.github.io/odespy/doc/pub/tutorial/html/main_odespy.html
"""
u_0, u_1, t = variables('u_0, u_1, t')
model_dict = {D(u_0, t): u_1, D(u_1, t): 3 * (1 - u_0**2) * u_1 - u_1}
ode_model = ODEModel(model_dict, initial={t: 0.0, u_0: 2.0, u_1: 1.0})
def test_neg():
"""
Test negation of all model types
"""
x, y_1, y_2 = variables('x, y_1, y_2')
a, b = parameters('a, b')
model_dict = {y_2: a * x ** 2, y_1: 2 * x * b}
model = Model(model_dict)
model_neg = - model
for key in model:
assert model[key] == - model_neg[key]
# Constraints
constraint = Model.as_constraint(Eq(a * x, 2), model)
constraint_neg = - constraint
# for key in constraint:
assert constraint[constraint.dependent_vars[0]] == - constraint_neg[constraint_neg.dependent_vars[0]]
# ODEModel
odemodel = ODEModel({D(y_1, x): a * x}, initial={a: 1.0})
odemodel_neg = - odemodel
for key in odemodel:
assert odemodel[key] == - odemodel_neg[key]
# For models with interdependency, negation should only change the
# dependent components.
model_dict = {x: y_1**2, y_1: a * y_2 + b}
model = Model(model_dict)
model_neg = - model
for key in model:
if key in model.dependent_vars:
assert model[key] == - model_neg[key]
elif key in model.interdependent_vars:
assert model[key] == model_neg[key]
else:
pytest.fail()
def oneProductModel(kABval=1e-2,
conc0=50e-3,
tvec=np.linspace(0, 200000, 100)):
# Here we describe a model with A+B->AB
A, B, AB, t = variables('A, B, AB, t')
tdata = [0, 1, 2]
kAB = Parameter('kAB', kABval) # Rate constant for formation of AB
# here's a list of rate expressions for each component in the mixture
model_dict = {
D(AB, t): kAB * A * B,
D(A, t): -kAB * A * B,
D(B, t): -(kAB * A * B),
}
# here we define the ODE model and specify the start concentrations of each reagent
ode_model = ODEModel(model_dict,
initial={
t: 0.0,
A: conc0,
B: conc0,
AB: 0,
})
# and then we fit the ODE model
fit = Fit(ode_model, t=tdata, A=None, B=None, AB=None)
fit_result = fit.execute()
# Generate some data
ans = ode_model(t=tvec, **fit_result.params)._asdict()
# and plot it
plt.plot(tvec, ans[AB], label='[AB]')
#plt.plot(tvec, BCres, label='[BC]')
#plt.scatter(tdata, adata)
plt.ylabel('Conc [M]')
plt.xlabel('Time [s]')
plt.legend()
plt.show()
def test_known_solution(self):
p, c1, c2 = parameters('p, c1, c2')
y, t = variables('y, t')
p.value = 3.0
model_dict = {
D(y, t): -p * y,
}
# Lets say we know the exact solution to this problem
sol = c1 * exp(-p * t)
# Generate some data
tdata = np.linspace(0, 3, 101)
ydata = sol(t=tdata, c1=1.0, p=3.22)
ode_model = ODEModel(model_dict, initial={t: 0.0, y: 1.0})
fit = Fit(ode_model, t=tdata, y=ydata)
fit_result = fit.execute()
y_sol, = ode_model(tdata, **fit_result.params)
self.assertAlmostEqual(3.22, fit_result.value(p))
def test_simple_kinetics():
"""
Simple kinetics data to test fitting
"""
tdata = np.array([10, 26, 44, 70, 120])
adata = 10e-4 * np.array([44, 34, 27, 20, 14])
a, b, t = variables('a, b, t')
k, a0 = parameters('k, a0')
k.value = 0.01
# a0.value, a0.min, a0.max = 54 * 10e-4, 40e-4, 60e-4
a0 = 54 * 10e-4
model_dict = {
D(a, t): -k * a**2,
D(b, t): k * a**2,
}
ode_model = ODEModel(model_dict, initial={t: 0.0, a: a0, b: 0.0})
fit = Fit(ode_model, t=tdata, a=adata, b=None)
fit_result = fit.execute(tol=1e-9)
assert fit_result.value(k) == pytest.approx(4.302875e-01, 1e-5)
assert fit_result.stdev(k) == pytest.approx(6.447068e-03, 1e-5)
import numpy as np
from symfit.contrib.interactive_guess import InteractiveGuess2D
# First order reaction kinetics. Data taken from http://chem.libretexts.org/Core/Physical_Chemistry/Kinetics/Rate_Laws/The_Rate_Law
tdata = np.array([0, 0.9184, 9.0875, 11.2485, 17.5255, 23.9993, 27.7949,
31.9783, 35.2118, 42.973, 46.6555, 50.3922, 55.4747, 61.827,
65.6603, 70.0939])
concentration_A = np.array([0.906, 0.8739, 0.5622, 0.5156, 0.3718, 0.2702, 0.2238,
0.1761, 0.1495, 0.1029, 0.086, 0.0697, 0.0546, 0.0393,
0.0324, 0.026])
concentration_B = np.max(concentration_A) - concentration_A
# Define our ODE model
A, B, t = variables('A, B, t')
k = Parameter()
model_dict = {
D(A, t): - k * A**2,
D(B, t): k * A**2
}
model = ODEModel(model_dict, initial={t: tdata[0], A: concentration_A[0], B: 0})
guess = InteractiveGuess2D(model, A=concentration_A, B=concentration_B, t=tdata, n_points=250)
guess.execute()
print(guess)
fit = NumericalLeastSquares(model, A=concentration_A, B=concentration_B, t=tdata)
fit_result = fit.execute()
print(fit_result)
def twoProductModel(kABval=1e-2,
kBCval=1e-2,
conc0=50e-3,
tvec=np.linspace(0, 200000, 100)):
# conc0 is initial concentration
tdata = [0, 1, 2]
# Here we describe a model with A+B->AB and B+C->BC
A, B, C, AB, BC, t = variables('A, B, C, AB, BC, t')
kAB = Parameter('kAB', kABval) # Rate constant for formation of AB
kBC = Parameter('kBC', kBCval) # rate constant for formation of BC
# here's a list of rate expressions for each component in the mixture
model_dict = {
D(AB, t): kAB * A * B,
D(BC, t): kBC * B * C,
D(A, t): -kAB * A * B,
D(B, t): -(kAB * A * B + kBC * B * C),
D(C, t): -kBC * B * C,
}
# here we define the ODE model and specify the start concentrations of each reagent
ode_model = ODEModel(model_dict,
initial={
t: 0.0,
A: conc0,
B: conc0,
C: conc0,
AB: 0,
BC: 0
})
# and then we fit the ODE model
fit = Fit(ode_model, t=tdata, A=None, B=None, AB=None, BC=None, C=None)
fit_result = fit.execute()
# Generate some data
ans = ode_model(t=tvec, **fit_result.params)._asdict()
# and plot it
plt.plot(tvec, ans[AB], label='[AB]')
plt.plot(tvec, ans[BC], label='[BC]')
#plt.scatter(tdata, adata)
plt.ylabel('Conc [M]')
plt.xlabel('Time [s]')
plt.legend()
plt.show()
res = [ans[AB][-1], ans[BC][-1]]
resNorm = res / sum(res)
plt.bar([1, 2], 100 * resNorm)
plt.xticks([1, 2], ('[AB]', '[BC]'))
plt.ylabel('%age at eq')
plt.show()
# enhancement, in percent, compared to equal concentrations everywhere
resEnh = 100 * (
(np.array(resNorm)) - 1 / len(resNorm)) / (1 / len(resNorm))
# rounding errors can give a spurious difference: set small values to zero
resEnh[abs(resEnh) < 1e-5] = 0
if (sum(abs(resEnh)) > 0):
plt.bar([1, 2], resEnh)
plt.xticks([1, 2], ('[AB]', '[BC]'))
plt.ylabel('%age at eq')
plt.title('Enhancement / %')
plt.show()
else:
print("No enhancement compared to equal rates")
def square(kABval=1e-2,
kACval=1e-2,
kBDval=1e-2,
kCDval=1e-2,
kBCval=1e-2,
kADval=1e-2,
conc0=50e-3,
tvec=np.linspace(0, 200000, 100)):
# Here we describe a model with A+B->AB
A, B, C, Di, AB, AC, CD, BD, AD, BC, t = variables(
'A, B, C, Di, AB, AC, CD, BD, AD, BC, t')
tdata = [0, 1, 2, 100, 1000, 10000]
kAB = Parameter('kAB', kABval) # Rate constant for formation of AB
kAC = Parameter('kAC', kACval) # Rate constant for formation of AC
kBD = Parameter('kBD', kBDval) # Rate constant for formation of BD
kCD = Parameter('kCD', kCDval) # Rate constant for formation of CD
kBC = Parameter(
'kBC',
kBCval) # Rate constant for formation of BC ## cross-connection
kAD = Parameter(
'kAD',
kADval) # Rate constant for formation of AD ## cross-connection
# here's a list of rate expressions for each component in the mixture
# here I'm calling the concentration of D as'Di' to avoid confusion
model_dict = {
D(AB, t): kAB * A * B,
D(AC, t): kAC * A * C,
D(BD, t): kBD * B * Di,
D(CD, t): kCD * C * Di,
D(BC, t): kBC * B * C,
D(AD, t): kAD * A * Di,
D(A, t): -(kAB * A * B + kAC * A * C + kAD * A * Di),
D(B, t): -(kAB * A * B + kBD * B * Di + kBC * B * C),
D(C, t): -(kAC * A * C + kCD * C * Di + kBC * B * C),
D(Di, t): -(kBD * B * Di + kCD * C * Di + kAD * A * Di),
}
# here we define the ODE model and specify the start concentrations of each reagent
ode_model = ODEModel(model_dict,
initial={
t: 0.0,
A: conc0,
B: conc0,
C: conc0,
Di: conc0,
AB: 0,
BC: 0,
AC: 0,
BD: 0,
CD: 0,
AD: 0
})
# and then we fit the ODE model
fit = Fit(ode_model,
t=tdata,
A=None,
B=None,
C=None,
Di=None,
AB=None,
BC=None,
AC=None,
BD=None,
CD=None,
AD=None)
fit_result = fit.execute()
# Generate some data
ans = ode_model(t=tvec, **fit_result.params)._asdict()
# and plot it
plt.plot(tvec, ans[AB], label='[AB]')
plt.plot(tvec, ans[AC], label='[AC]')
plt.plot(tvec, ans[CD], label='[CD]')
plt.plot(tvec, ans[BC], label='[BC]')
plt.plot(tvec, ans[BD], label='[BD]')
plt.plot(tvec, ans[AD], label='[AD]')
#plt.plot(tvec, BCres, label='[BC]')
#plt.scatter(tdata, adata)
plt.ylabel('Conc [M]')
plt.xlabel('Time [s]')
plt.legend()
plt.show()
res = [
ans[AB][-1], ans[AC][-1], ans[CD][-1], ans[BC][-1], ans[BD][-1],
ans[AD][-1]
]
resNorm = res / sum(res)
plt.bar([1, 2, 3, 4, 5, 6], 100 * resNorm)
plt.xticks([1, 2, 3, 4, 5, 6],
('[AB]', '[AC]', '[CD]', '[BC]', '[BD]', '[AD]'))
plt.ylabel('%age at eq')
plt.show()
# enhancement, in percent, compared to equal concentrations everywhere
resEnh = 100 * (
(np.array(resNorm)) - 1 / len(resNorm)) / (1 / len(resNorm))
# rounding errors can give a spurious difference: set small values to zero
resEnh[abs(resEnh) < 1e-5] = 0
if (sum(abs(resEnh)) > 0):
yval = [1, 2, 3, 4, 5, 6]
plt.bar(yval, resEnh)
plt.xticks(yval, ('[AB]', '[AC]', '[CD]', '[BC]', '[BD]', '[AD]'))
plt.ylabel('%age at eq')
plt.title('Enhancement / %')
plt.show()
else:
print("No enhancement compared to equal rates")
0, 0.9184, 9.0875, 11.2485, 17.5255, 23.9993, 27.7949, 31.9783, 35.2118,
42.973, 46.6555, 50.3922, 55.4747, 61.827, 65.6603, 70.0939
])
concentration = np.array([
0.906, 0.8739, 0.5622, 0.5156, 0.3718, 0.2702, 0.2238, 0.1761, 0.1495,
0.1029, 0.086, 0.0697, 0.0546, 0.0393, 0.0324, 0.026
])
# Define our ODE model
A, B, t = variables('A, B, t')
k = Parameter('k')
model = ODEModel({
D(A, t): -k * A,
D(B, t): k * A
},
initial={
t: tdata[0],
A: concentration[0],
B: 0.0
})
fit = Fit(model, A=concentration, t=tdata)
fit_result = fit.execute()
print(fit_result)
# Plotting, irrelevant to the symfit part.
t_axis = np.linspace(0, 80)
A_fit, B_fit, = model(t=t_axis, **fit_result.params)
plt.scatter(tdata, concentration)
plt.plot(t_axis, A_fit, label='[A]')
# SPDX-License-Identifier: MIT
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from symfit import variables, Parameter, Fit, D, ODEModel
import numpy as np
from symfit.contrib.interactive_guess import InteractiveGuess
# First order reaction kinetics. Data taken from
# http://chem.libretexts.org/Core/Physical_Chemistry/Kinetics/Rate_Laws/The_Rate_Law
tdata = np.array([0, 0.9184, 9.0875, 11.2485, 17.5255, 23.9993, 27.7949,
31.9783, 35.2118, 42.973, 46.6555, 50.3922, 55.4747, 61.827,
65.6603, 70.0939])
concentration = np.array([0.906, 0.8739, 0.5622, 0.5156, 0.3718, 0.2702, 0.2238,
0.1761, 0.1495, 0.1029, 0.086, 0.0697, 0.0546, 0.0393,
0.0324, 0.026])
# Define our ODE model
A, t = variables('A, t')
k = Parameter('k')
model = ODEModel({D(A, t): - k * A}, initial={t: tdata[0], A: concentration[0]})
guess = InteractiveGuess(model, A=concentration, t=tdata, n_points=250)
guess.execute()
print(guess)
fit = Fit(model, A=concentration, t=tdata)
fit_result = fit.execute()
print(fit_result)
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns
# Example of the easy of use of the symfit ODE integration syntax.
a, b, c, d, t = variables('a, b, c, d, t')
k, p, l, m = parameters('k, p, l, m')
a0 = 10
b = a0 - d + a # [B] is not independent.
model_dict = {
D(d, t): l * c * b - m * d,
D(c, t): k * a * b - p * c - l * c * b + m * d,
D(a, t): -k * a * b + p * c,
}
model = ODEModel(model_dict, initial={t: 0.0, a: a0, c: 0.0, d: 0.0})
# Generate some data
tdata = np.linspace(0, 3, 1000)
# Eval the normal way.
AA, AAB, BAAB = model(t=tdata, k=0.1, l=0.2, m=.3, p=0.3)
plt.plot(tdata, AA, color='red', label='[AA]')
plt.plot(tdata, AAB, color='blue', label='[AAB]')
plt.plot(tdata, BAAB, color='green', label='[BAAB]')
plt.plot(tdata, b(d=BAAB, a=AA), color='pink', label='[B]')
# plt.plot(tdata, AA + AAB + BAAB, color='black', label='total')
plt.legend()
plt.show()
def generalModel(rates, conc0, tvec=np.linspace(0, 200000, 100)):
# make a list of parameters
numEl = np.shape(rates)[0]
model_dict = {}
pp = ()
vv = ()
# first create variables for initial species
for ii in np.arange(0, numEl):
var = Variable(chr(ii + 65))
vv = vv + (var, )
t = Variable('t')
kdict = {}
# then create variables for products and rate constants (parameters)
ik = 0
for ii in np.arange(0, numEl):
for ij in np.arange(0, numEl):
if ii < ij:
var = Variable(chr(ii + 65) + chr(ij + 65))
vv = vv + (var, )
par = Parameter('k' + chr(ii + 65) + chr(ij + 65), rates[ii,
ij])
pp = pp + (par, )
# a dict so we can easily find rate constant indices later (this is hacky but if it works...)
kdict[str(ii) + str(ij)] = ik
kdict[str(ij) + str(ii)] = ik
ik = ik + 1
# now create model
ik = 0
for ii in np.arange(0, numEl):
# this will be an expression for what's happening to the SM concentration. It's easiest if we just add each
# relevant product forming reaction to this expression, then take its negative later on
smexpr = 0
for ij in np.arange(0, numEl):
if ii < ij:
model_dict[D(
vv[numEl + ik],
t)] = pp[kdict[str(ii) + str(ij)]] * vv[ii] * vv[ij]
smexpr = smexpr + pp[kdict[str(ii) +
str(ij)]] * vv[ii] * vv[ij]
ik = ik + 1
elif ii > ij:
# need to have this otherwise we miss a lot of contributions for B/C/D
smexpr = smexpr + pp[kdict[str(ij) +
str(ii)]] * vv[ij] * vv[ii]
# we're still in the loop here, at the level of starting materials. This part creates d[A]/dt (etc for B, C, D)
model_dict[D(vv[ii], t)] = -(smexpr)
# set initial parameters: at time 0, all concentrations of products are zero and concentration of SMs is fixed
# (this could be changed to allow variable concs TODO)
# while we're here, also set the arguments for the fit command later on to zero.
initial = {
t: 0.0,
}
fitargs = {}
for el in vv:
if len(el.name) == 1:
initial[el] = conc0
else:
initial[el] = 0
fitargs[el.name] = None
# define the model
ode_model = ODEModel(model_dict, initial=initial)
# honestly I don't know what this does but it seems to have no effect on results (based on my incomplete testing!)
# it just needs to be there and not 'None'
tdata = [0, 1, 2]
# and then we fit the ODE model
fit = Fit(ode_model, **fitargs, t=tdata)
fit_result = fit.execute()
# Generate some data from our fit model
ans = ode_model(t=tvec, **fit_result.params)._asdict()
# and plot it
result = []
legtxt = ()
for ii in np.arange(numEl, len(vv), 1):
plt.plot(tvec, ans[vv[ii]], label=vv[ii].name)
result.append(ans[vv[ii]][-1])
legtxt = legtxt + (vv[ii].name, )
plt.ylabel('Conc [M]')
plt.xlabel('Time [s]')
plt.legend()
plt.show()
resNorm = result / sum(result)
xpos = np.arange(1, len(resNorm) + 1, 1)
plt.bar(xpos, 100 * resNorm)
plt.xticks(xpos, legtxt)
plt.ylabel('%age at eq')
plt.show()
# enhancement, in percent, compared to equal concentrations everywhere
resEnh = 100 * (
(np.array(resNorm)) - 1 / len(resNorm)) / (1 / len(resNorm))
# rounding errors can give a spurious difference: set small values to zero
resEnh[abs(resEnh) < 1e-5] = 0
if (sum(abs(resEnh)) > 0):
plt.bar(xpos, resEnh)
plt.xticks(xpos, legtxt)
plt.ylabel('%age at eq')
plt.title('Enhancement / %')
plt.show()
else:
print(
"No enhancement compared to equal rates in a fully-connected network"
)
