def createSurrogateModel(modelData, data):
X = data['X']
Y = data['dX']
if modelData.nMonomials == 0:
psi = Identity
P = np_.array(range(X[0].shape[1]))
else:
psi = observables.monomials(modelData.nMonomials)
P = np_.array(range(1, X[0].shape[1] + 1))
for i in range(len(X)):
PsiX = psi(X[i].T)
if modelData.nMonomials == 0:
dPsiY = Y[i].T
else:
dPsiY = np_.einsum('ijk,jk->ik', psi.diff(X[i].T), Y[i].T)
Gi = PsiX @ PsiX.T
Ai = PsiX @ dPsiY.T
Ki = sp_.linalg.pinv(Gi) @ Ai
if i == 0:
K = np_.zeros([Ki.shape[0], Ki.shape[1], len(X)], dtype=float)
A = np_.zeros([Ki.shape[0], Ki.shape[1], len(X)], dtype=float)
G = np_.zeros([Ki.shape[0], Ki.shape[1], len(X)], dtype=float)
m = np_.zeros([len(X)], dtype=float)
K[:, :, i] = Ki.transpose()
A[:, :, i] = Ai
G[:, :, i] = Gi
m[i] = float(X[i].shape[0])
setattr(modelData, 'psi', psi)
setattr(modelData, 'K', K)
setattr(modelData, 'A', A)
setattr(modelData, 'G', G)
setattr(modelData, 'm', m)
setattr(modelData, 'P', P)
return modelData
#%% plot eigenvalues
plt.figure()
plt.plot(d, '.')
plt.title('Spectrum')
#%% plot eigenfunctions
ind, = np.where(d < -0.1)
for i in ind[:6]:
plt.figure()
Omega.plot(np.real(W[:, i] / np.amax(abs(W[:, i]))))
plt.ylim((-1, 1))
plt.title('lambda = %f' % np.real(d[i]))
#%% direct kernelization for kernels with finite-dimensional feature space
psi = observables.monomials(5)
PsiX = psi(X)
dPsiY = np.einsum('ijk,jk->ik', psi.diff(X), Y)
if not (Z is None): # stochastic dynamical system
n = PsiX.shape[0] # number of basis functions
ddPsiX = psi.ddiff(X) # secplond-order derivatives
S = np.einsum('ijk,ljk->ilk', Z, Z) # sigma \cdot sigma^T
for i in range(n):
dPsiY[i, :] += 0.5 * np.sum(ddPsiX[i, :, :, :] * S, axis=(0, 1))
G_00 = PsiX.T @ PsiX
G_10 = dPsiY.T @ PsiX
A = sp.linalg.pinv(G_00 + epsilon * np.eye(m), rcond=1e-15) @ G_10
d, V = algorithms.sortEig(A, evs=m, which='SM')
V = G_00 @ V
import numpy as np
import os
import d3s.observables as observables
import auxiliary.algorithms as algorithms
from auxiliary.kramers_moyal import kramersmoyal
# Maximum degree of monomials
degree = 3
data_path = 'data/raw/'
save_path = 'data/processed/matrix_'
# Define observables
psi = observables.monomials(degree)
for filename in os.listdir(data_path):
if filename[-3::] != 'npz':
continue
with np.load(data_path + filename) as data:
print('Available in this data set:', data.files)
trajectory = data['trajectory']
x_init = data['x_init']
num_agents = data['num_agents']
num_testpoints = data['num_trainingpoints']
num_samples = data['num_samples']
T_max = data['T_max']
gamma = data['gamma']
def __init__(self):
self.p = observables.monomials(2)
# define domain
bounds = sp.array([[-2, 2], [-2, 2]])
boxes = sp.array([50, 50])
Omega = domain.discretization(bounds, boxes)
# define system
gamma = -0.8
delta = -0.7
def b(x):
return np.array([gamma * x[0, :], delta * (x[1, :] - x[0, :]**2)])
# define observables
psi = observables.monomials(8)
# generate data
X = Omega.rand(1000) # generate test points
Y = b(X)
# apply generator EDMD
evs = 8 # number of eigenvalues/eigenfunctions to be computed
K, d, V = algorithms.gedmd(X, Y, None, psi, evs=evs, operator='K')
# printMatrix(K, 'K_gEDMD')
printVector(np.real(d), 'd_gEDMD')
V[:, 1] /= V[3, 1]
V[:, 3] /= V[10, 3]
V[:, 4] /= V[6, 4] # normalize eigenvectors for convenience
for i in range(evs):
def data_sde(L, p, x_init, T_max, t_step, seed=None):
"""
Euler-Maruyama scheme to simulate the reduced SDE
Parameters
----------
L : ndarray
Koopman generator approximation matrix.
p : int
Degree of highest-order monomial.
x_init : ndarray
Initial state.
T_max : float
Time horizon for simulation.
t_step : float
Time step size.
seed : int, optional
Seed of random process. The default is None.
Returns
-------
C : ndarray
Trajectory of the SDE simulated for interval [0, T_max].
"""
if seed is not None:
np.random.seed(seed)
num_types = len(x_init)
# Define observables
psi = observables.monomials(p)
# Number of timestep to be simulated
num_timesteps = int(np.round(T_max / t_step)) + 1
C = np.zeros([num_types - 1, num_timesteps])
C[:, 0] = x_init[0:num_types - 1]
for k in range(num_timesteps - 1):
# Get random number
Wt = np.random.normal(0, 1, num_types - 1)
# Evaluate drift and diffusion in X given the data-driven L
X = C[:, k]
X = np.expand_dims(X, axis=1)
Psi_c = psi(X)
# Calculate drift
b_c = L[:, 1:num_types].T @ Psi_c
b_c = np.squeeze(b_c)
# Calculate diffusion
a_c_11 = L[:, 3].T @ Psi_c - 2 * b_c[0] * X[0, :]
a_c_12 = L[:, 4].T @ Psi_c - b_c[0] * X[1, :] - b_c[1] * X[0, :]
a_c_22 = L[:, 5].T @ Psi_c - 2 * b_c[1] * X[1, :]
A = np.empty([num_types - 1, num_types - 1])
A[0, 0] = a_c_11
A[1, 0] = a_c_12
A[0, 1] = a_c_12
A[1, 1] = a_c_22
# The matrix A can have eigenvalues that are numerically (close to)
# zero. If the Cholesky decomposition cannot be computed, the diffusion
# term sigma will not be updated in this step
try:
__ = sigma.shape
except NameError:
sigma = np.zeros_like(A)
try:
sigma = sp.linalg.cholesky(A, lower=True)
except Exception as excp:
pass
C[:, k + 1] = C[:, k] + t_step * b_c + np.sqrt(t_step) * sigma @ Wt
# Calculate missing last entrie
C = np.vstack((C, np.zeros(num_timesteps)))
C[2, :] = 1 - C[0, :] - C[1, :]
return C
