def train_single(trainsize, r, regs):
"""Train and save a ROM with the given dimension and regularization
hyperparameters.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM.
r : int
Dimension of the desired ROM. Also the number of retained POD modes
(left singular vectors) used to project the training data.
regs : two or three non-negative floats
Regularization hyperparameters (first-order, quadratic, cubic) to use
in the Operator Inference least-squares problem for training the ROM.
"""
utils.reset_logger(trainsize)
# Validate inputs.
modelform = get_modelform(regs)
check_lstsq_size(trainsize, r, modelform)
check_regs(regs)
# Load training data.
Q_, Qdot_, t = utils.load_projected_data(trainsize, r)
U = config.U(t)
# Train and save the ROM.
with utils.timed_block(f"Training ROM with k={trainsize:d}, "
f"{config.REGSTR(regs)}"):
rom = opinf.InferredContinuousROM(modelform)
rom.fit(None, Q_, Qdot_, U, P=regularizer(r, *list(regs)))
save_trained_rom(trainsize, r, regs, rom)
def train_and_save_all(trainsize, num_modes, regs):
"""Train and save ROMs with the given dimension and regularization.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM(s).
num_modes : int or list(int)
Dimension of the ROM(s) to train, i.e., the number of retained POD
modes (left singular vectors) used to project the training data.
regs : float or list(float)
regularization parameter(s) to use in the training.
"""
utils.reset_logger(trainsize)
logging.info(f"TRAINING {len(num_modes)*len(regs)} ROMS")
for r in num_modes:
# Load training data.
X_, Xdot_, time_domain, _ = utils.load_projected_data(trainsize, r)
# Evaluate inputs over the training time domain.
Us = config.U(time_domain)
# Train and save each ROM.
for reg in regs:
with utils.timed_block(f"Training ROM with r={r:d}, reg={reg:e}"):
rom = train_rom(X_, Xdot_, Us, reg)
if rom:
rom.save_model(config.rom_path(trainsize, r, reg),
save_basis=False, overwrite=True)
def train_single(trainsize, r, regs):
"""Train and save a ROM with the given dimension and regularization
hyperparameters.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM.
r : int
Dimension of the desired ROM. Also the number of retained POD modes
(left singular vectors) used to project the training data.
regs : two positive floats
Regularization hyperparameters (non-quadratic, quadratic) to use in
the Operator Inference least-squares problem for training the ROM.
"""
utils.reset_logger(trainsize)
# Validate inputs.
d = check_lstsq_size(trainsize, r)
λ1, λ2 = check_regs(regs)
# Load training data.
Q_, Qdot_, t = utils.load_projected_data(trainsize, r)
U = config.U(t)
# Train and save the ROM.
with utils.timed_block(f"Training ROM with k={trainsize:d}, "
f"r={r:d}, λ1={λ1:.0f}, λ2={λ2:.0f}"):
rom = roi.InferredContinuousROM(config.MODELFORM)
rom.fit(None, Q_, Qdot_, U, P=regularizer(r, d, λ1, λ2))
save_trained_rom(trainsize, r, regs, rom)
def _train_minimize_1D(trainsize, r, regs, testsize=None, margin=1.1):
"""Train ROMs with the given dimension(s), saving only the ROM with
the least training error that satisfies a bound on the integrated POD
coefficients, using a search algorithm to choose the regularization
parameter.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM.
r : int
Dimension of the desired ROM. Also the number of retained POD modes
(left singular vectors) used to project the training data.
regs : two non-negative floats
Bounds for the (single) regularization hyperparameter to use in the
Operator Inference least-squares problem for training the ROM.
testsize : int
Number of time steps for which a valid ROM must satisfy the POD bound.
margin : float ≥ 1
Amount that the integrated POD coefficients of a valid ROM are allowed
to deviate in magnitude from the maximum magnitude of the training
data Q, i.e., bound = margin * max(abs(Q)).
"""
utils.reset_logger(trainsize)
# Parse aguments.
check_lstsq_size(trainsize, r, modelform="cAHB")
log10regs = np.log10(regs)
# Load training data.
t = utils.load_time_domain(testsize)
Q_, Qdot_, _ = utils.load_projected_data(trainsize, r)
U = config.U(t[:trainsize])
# Compute the bound to require for integrated POD modes.
B = margin * np.abs(Q_).max()
# Create a solver mapping regularization hyperparameters to operators.
with utils.timed_block(f"Constructing least-squares solver, r={r:d}"):
rom = opinf.InferredContinuousROM("cAHB")
rom._construct_solver(None, Q_, Qdot_, U, 1)
# Test each regularization hyperparameter.
def training_error(log10reg):
"""Return the training error resulting from the regularization
hyperparameters λ1 = λ2 = 10^log10reg. If the resulting model
violates the POD bound, return "infinity".
"""
λ = 10**log10reg
# Train the ROM on all training snapshots.
with utils.timed_block(f"Testing ROM with λ={λ:e}"):
rom._evaluate_solver(λ)
# Simulate the ROM over the full domain.
with np.warnings.catch_warnings():
np.warnings.simplefilter("ignore")
q_rom = rom.predict(Q_[:, 0], t, config.U, method="RK45")
# Check for boundedness of solution.
if not is_bounded(q_rom, B):
return _MAXFUN
# Calculate integrated relative errors in the reduced space.
return opinf.post.Lp_error(Q_, q_rom[:, :trainsize],
t[:trainsize])[1]
opt_result = opt.minimize_scalar(training_error,
method="bounded",
bounds=log10regs)
if opt_result.success and opt_result.fun != _MAXFUN:
λ = 10**opt_result.x
with utils.timed_block(f"Best regularization for k={trainsize:d}, "
f"r={r:d}: λ={λ:.0f}"):
rom._evaluate_solver(λ)
save_trained_rom(trainsize, r, (λ, λ), rom)
else:
message = "Regularization search optimization FAILED"
print(message)
logging.info(message)
def train_gridsearch(trainsize, r, regs, testsize=None, margin=1.1):
"""Train ROMs with the given dimension over a grid of potential
regularization hyperparameters, saving only the ROM with the least
training error that satisfies a bound on the integrated POD coefficients.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM.
r : int
Dimension of the desired ROM. Also the number of retained POD modes
(left singular vectors) used to project the training data.
regs : (float, float, int, float, float, int)
Bounds and sizes for the grid of regularization hyperparameters.
First-order: search in [regs[0], regs[1]] at regs[2] points.
Quadratic: search in [regs[3], regs[4]] at regs[5] points.
Cubic: search in [regs[6], regs[7]] at regs[8] points.
testsize : int
Number of time steps for which a valid ROM must satisfy the POD bound.
margin : float ≥ 1
Amount that the integrated POD coefficients of a valid ROM are allowed
to deviate in magnitude from the maximum magnitude of the training
data Q, i.e., bound = margin * max(abs(Q)).
"""
utils.reset_logger(trainsize)
# Parse aguments.
if len(regs) not in [6, 9]:
raise ValueError("6 or 9 regs required (bounds / sizes of grids")
grids = []
for i in range(0, len(regs), 3):
check_regs(regs[i:i + 2])
grids.append(
np.logspace(np.log10(regs[i]), np.log10(regs[i + 1]),
int(regs[i + 2])))
modelform = get_modelform(grids)
d = check_lstsq_size(trainsize, r, modelform)
# Load training data.
t = utils.load_time_domain(testsize)
Q_, Qdot_, _ = utils.load_projected_data(trainsize, r)
U = config.U(t[:trainsize])
# Compute the bound to require for integrated POD modes.
M = margin * np.abs(Q_).max()
# Create a solver mapping regularization hyperparameters to operators.
num_tests = np.prod([grid.size for grid in grids])
print(f"TRAINING {num_tests} ROMS")
with utils.timed_block(f"Constructing least-squares solver, r={r:d}"):
rom = opinf.InferredContinuousROM(modelform)
rom._construct_solver(None, Q_, Qdot_, U, np.ones(d))
# Test each regularization hyperparameter.
errors_pass = {}
errors_fail = {}
for i, regs in enumerate(itertools.product(*grids)):
with utils.timed_block(f"({i+1:d}/{num_tests:d}) Testing ROM with "
f"{config.REGSTR(regs)}"):
# Train the ROM on all training snapshots.
rom._evaluate_solver(regularizer(r, *list(regs)))
# Simulate the ROM over the full domain.
with np.warnings.catch_warnings():
np.warnings.simplefilter("ignore")
q_rom = rom.predict(Q_[:, 0], t, config.U, method="RK45")
# Check for boundedness of solution.
errors = errors_pass if is_bounded(q_rom, M) else errors_fail
# Calculate integrated relative errors in the reduced space.
if q_rom.shape[1] > trainsize:
errors[tuple(regs)] = opinf.post.Lp_error(
Q_, q_rom[:, :trainsize], t[:trainsize])[1]
# Choose and save the ROM with the least error.
if not errors_pass:
message = f"NO STABLE ROMS for r={r:d}"
print(message)
logging.info(message)
return
err2reg = {err: reg for reg, err in errors_pass.items()}
regs = list(err2reg[min(err2reg.keys())])
with utils.timed_block(f"Best regularization for k={trainsize:d}, "
f"r={r:d}: {config.REGSTR(regs)}"):
rom._evaluate_solver(regularizer(r, *regs))
save_trained_rom(trainsize, r, regs, rom)
def train_with_minimization(trainsize, num_modes, regs,
testsize=None, margin=1.5):
"""Train ROMs with the given dimension(s), saving only the ROM with
the least training error that satisfies a bound on the integrated POD
coefficients, using a search algorithm to choose the regularization
parameter.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM(s).
num_modes : int or list(int)
Dimension of the ROM(s) to train, i.e., the number of retained POD
modes (left singular vectors) used to project the training data.
regs : [float, float]
regularization parameter(s) to use in the training.
testsize : int
Number of time steps for which a valid ROM must satisfy the POD bound.
margin : float >= 1
Amount that the integrated POD coefficients of a valid ROM are allowed
to deviate in magnitude from the maximum magnitude of the training
data Q, i.e., bound = margin * max(abs(Q)).
"""
utils.reset_logger(trainsize)
# Parse aguments.
if np.isscalar(num_modes):
num_modes = [num_modes]
if np.isscalar(regs) or len(regs) != 2:
raise ValueError("2 regularizations required (reg_low, reg_high)")
bounds = np.log10(regs)
# Load the full time domain and evaluate the input function.
t = utils.load_time_domain(testsize)
Us = config.U(t)
for r in num_modes:
# Load training data.
X_, Xdot_, _, scales = utils.load_projected_data(trainsize, r)
# Compute the bound to require for integrated POD modes.
B = margin * np.abs(X_).max()
# Test each regularization parameter.
def training_error_from_rom(log10reg):
reg = 10**log10reg
# Train the ROM on all training snapshots.
with utils.timed_block(f"Testing ROM with r={r:d}, reg={reg:e}"):
rom = train_rom(X_, Xdot_, Us[:trainsize], reg)
if not rom:
return _MAXFUN
# Simulate the ROM over the full domain.
with np.warnings.catch_warnings():
np.warnings.simplefilter("ignore")
x_rom = rom.predict(X_[:,0], t, config.U, method="RK45")
# Check for boundedness of solution.
if not is_bounded(x_rom, B):
return _MAXFUN
# Calculate integrated relative errors in the reduced space.
return roi.post.Lp_error(X_, x_rom[:,:trainsize],
t[:trainsize])[1]
opt_result = opt.minimize_scalar(training_error_from_rom,
bounds=bounds, method="bounded")
if opt_result.success and opt_result.fun != _MAXFUN:
best_reg = 10 ** opt_result.x
best_rom = train_rom(X_, Xdot_, Us[:trainsize], best_reg)
save_best_trained_rom(trainsize, r, best_reg, best_rom)
else:
print(f"Regularization search optimization FAILED for r = {r:d}")
def train_with_gridsearch(trainsize, num_modes, regs,
testsize=None, margin=1.5):
"""Train ROMs with the given dimension(s) and regularization(s),
saving only the ROM with the least training error that satisfies
a bound on the integrated POD coefficients.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM(s).
num_modes : int or list(int)
Dimension of the ROM(s) to train, i.e., the number of retained POD
modes (left singular vectors) used to project the training data.
regs : float or list(float)
regularization parameter(s) to use in the training.
testsize : int
Number of time steps for which a valid ROM must satisfy the POD bound.
margin : float >= 1
Amount that the integrated POD coefficients of a valid ROM are allowed
to deviate in magnitude from the maximum magnitude of the training
data Q, i.e., bound = margin * max(abs(Q)).
"""
utils.reset_logger(trainsize)
# Parse aguments.
if np.isscalar(num_modes):
num_modes = [num_modes]
if np.isscalar(regs):
regs = [regs]
# Load the full time domain and evaluate the input function.
t = utils.load_time_domain(testsize)
Us = config.U(t)
logging.info(f"TRAINING {len(num_modes)*len(regs)} ROMS")
for ii,r in enumerate(num_modes):
# Load training data.
X_, Xdot_, _, scales = utils.load_projected_data(trainsize, r)
# Compute the bound to require for integrated POD modes.
M = margin * np.abs(X_).max()
# Test each regularization parameter.
trained_roms = {}
errors_pass = {}
errors_fail = {}
for reg in regs:
# Train the ROM on all training snapshots.
with utils.timed_block(f"Testing ROM with r={r:d}, reg={reg:e}"):
rom = train_rom(X_, Xdot_, Us[:trainsize], reg)
if not rom:
continue # Skip if training fails.
trained_roms[reg] = rom
# Simulate the ROM over the full domain.
with np.warnings.catch_warnings():
np.warnings.simplefilter("ignore")
x_rom = rom.predict(X_[:,0], t, config.U, method="RK45")
# Check for boundedness of solution.
errors = errors_pass if is_bounded(x_rom, M) else errors_fail
# Calculate integrated relative errors in the reduced space.
if x_rom.shape[1] > trainsize:
errors[reg] = roi.post.Lp_error(X_, x_rom[:,:trainsize],
t[:trainsize])[1]
# Choose and save the ROM with the least error.
plt.semilogx(list(errors_fail.keys()), list(errors_fail.values()),
f"C{ii}x", mew=1, label=fr"$r = {r:d}$, bound violated")
if not errors_pass:
print(f"NO STABLE ROMS for r = {r:d}")
continue
err2reg = {err:reg for reg,err in errors_pass.items()}
best_reg = err2reg[min(err2reg.keys())]
best_rom = trained_roms[best_reg]
save_best_trained_rom(trainsize, r, best_reg, best_rom)
plt.semilogx(list(errors_pass.keys()), list(errors_pass.values()),
f"C{ii}*", mew=0, label=fr"$r = {r:d}$, bound satisfied")
plt.axvline(best_reg, lw=.5, color=f"C{ii}")
plt.legend()
plt.xlabel(r"Regularization parameter $\lambda$")
plt.ylabel(r"ROM relative error $\frac"
r"{||\widehat{\mathbf{Q}} - \widetilde{\mathbf{Q}}'||}"
r"{||\widehat{\mathbf{Q}}||}$")
plt.ylim(0, 1)
plt.xlim(min(regs), max(regs))
plt.title(fr"$n_t = {trainsize}$")
utils.save_figure(f"regsweep_nt{trainsize:05d}.pdf")
def train_gridsearch(trainsize, r, regs, testsize=None, margin=1.5):
"""Train ROMs with the given dimension over a grid of potential
regularization hyperparameters, saving only the ROM with the least
training error that satisfies a bound on the integrated POD coefficients.
Parameters
----------
trainsize : int
Number of snapshots to use to train the ROM.
r : int
Dimension of the desired ROM. Also the number of retained POD modes
(left singular vectors) used to project the training data.
regs : (float, float, int, float, float, int)
Bounds and sizes for the grid of regularization parameters.
Linear: search in [regs[0], regs[1]] at regs[2] points.
Quadratic: search in [regs[3], regs[4]] at regs[5] points.
testsize : int
Number of time steps for which a valid ROM must satisfy the POD bound.
margin : float >= 1
Amount that the integrated POD coefficients of a valid ROM are allowed
to deviate in magnitude from the maximum magnitude of the training
data Q, i.e., bound = margin * max(abs(Q)).
"""
utils.reset_logger(trainsize)
# Parse aguments.
d = check_lstsq_size(trainsize, r)
if len(regs) != 6:
raise ValueError("len(regs) != 6 (bounds / sizes for parameter grid")
check_regs(regs[0:2])
check_regs(regs[3:5])
λ1grid = np.logspace(np.log10(regs[0]), np.log10(regs[1]), int(regs[2]))
λ2grid = np.logspace(np.log10(regs[3]), np.log10(regs[4]), int(regs[5]))
# Load training data.
t = utils.load_time_domain(testsize)
Q_, Qdot_, _ = utils.load_projected_data(trainsize, r)
U = config.U(t[:trainsize])
# Compute the bound to require for integrated POD modes.
M = margin * np.abs(Q_).max()
# Create a solver mapping regularization parameters to operators.
print(f"TRAINING {λ1grid.size*λ2grid.size} ROMS")
with utils.timed_block(f"Constructing least-squares solver, r={r:d}"):
rom = roi.InferredContinuousROM(config.MODELFORM)
rom._construct_solver(None, Q_, Qdot_, U, np.ones(d))
# Test each regularization parameter.
errors_pass = {}
errors_fail = {}
for λ1, λ2 in itertools.product(λ1grid, λ2grid):
with utils.timed_block(f"Testing ROM with λ1={λ1:5e}, λ2={λ2:5e}"):
# Train the ROM on all training snapshots.
rom._evaluate_solver(regularizer(r, d, λ1, λ2))
# Simulate the ROM over the full domain.
with np.warnings.catch_warnings():
np.warnings.simplefilter("ignore")
q_rom = rom.predict(Q_[:, 0], t, config.U, method="RK45")
# Check for boundedness of solution.
errors = errors_pass if is_bounded(q_rom, M) else errors_fail
# Calculate integrated relative errors in the reduced space.
if q_rom.shape[1] > trainsize:
errors[(λ1, λ2)] = roi.post.Lp_error(Q_, q_rom[:, :trainsize],
t[:trainsize])[1]
# Choose and save the ROM with the least error.
if not errors_pass:
message = f"NO STABLE ROMS for r={r:d}"
print(message)
logging.info(message)
return
err2reg = {err: reg for reg, err in errors_pass.items()}
λ1, λ2 = err2reg[min(err2reg.keys())]
with utils.timed_block(f"Best regularization for k={trainsize:d}, "
f"r={r:d}: λ1={λ1:.0f}, λ2={λ2:.0f}"):
rom._evaluate_solver(regularizer(r, d, λ1, λ2))
save_trained_rom(trainsize, r, (λ1, λ2), rom)
